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USIGP-FY76T\

JUNE 1976

FIRST ANNUAL REPORT OF

Ad Hoc Committeeon Geodynamics

toThe Federal Council

for Science and Technology

PREFACE

The ad hoc Committee on Geodynamics was established upon recognition ofthe need for an interagency mechanism for the coordination of U.S. Federalactivities in the International Geodynamics Project (IGP). At the fall 1973, plenarymeeting of the Federal Council for Science and Technology (FCST), theestablishment of an ad hoc Committee on the IGP was approved in principle. TheCommittee was formally established by the chairman of the FCST in amemorandum dated May 21, 1974.

The purpose of the ad hoc Committee is to ensure the planning andcoordination of Federal activities in the IGP and related matters. The Committeefosters studies and investigations considered appropriate to the IGP and annuallyreviews the Federal geodynamics programs and budget. It also serves as the focalpoint for liaison with the U.S. Geodynamics Committee of the National Academy ofSciences, and with other outside bodies concerned with the IGP.

Since its inception, the ad hoc Committee has met a total of fourteen times. Thefirst meeting was on August 29,1974 and the most recent meeting on June 17, 1976.

The present membership of the Committee is as follows:

William J. Best Department of DefenseFernand P. dePercinJohn G. Heacock

Member

A.P. Crary,chairman

Dallas Peck,vice-chairman

Gordon Lill

Carl Romney

Alternate

Richard S. Fiske

George Younger

Organization

National Science Foundation

Department of the Interior

Department of Commerce

Robert G. Morris

George A. Kolstad Jerry Harbour

Francis L. Williams Edward A. FlinnJoseph W. Siry

Observers

Robert D. Lanza

Arthur J. Zeizel

Jack W. Keely

David Katcher

Department of State

Energy Re search andDevelopment Administration

National Aeronautics andand Space Administration

Department of Health,Education and Welfare

Department of Housingand Urban Development

Environmental Protection Agency

National Advisory Committeeon Oceans and Atmosphere

Executive Secretary: Hugh W. Albers, National Science Foundation

First Annual Report on Federal Activities in Geodynamics

CONTENTS

Page

Background of Geodynamics 1

Societal Benefits from Geodynamics Studies 3

History of the International Geodynamics Project 8

Why the International Geodynamics Project is Timely 10

Questions for Geodynamics to Answer 11

Resume of Federal Activities in IGP, FY 74" FY 75, and FY 76 16

International Participation 23

Appendix I 25

Appendix II 27

Department of Commerce " 27Air Force 29ARPA 30Navy , 31ERDA 33NASA 35NSF 36USGS 40

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BACKGROUND OF GEODYNAMICS

The Earth Sciences are undergoing a period ofrapid advance, the result of a simplifying theorythat has unified geologic thinking and provided anew framework for interpretation of observational and experimental data. The major initialcontributions to the new concept came frommarine geology and geophysics, and seismology.These observations led to the theory that hasbecome known as plate tectonics, centering onthe concept that the earth's outer shell, consistingof the crust and upper part of the mantle, is madeup of a small number of very large semi-rigidpIa tes that move relative to one another. The

plate tectonics theory differs from continentaldrift theory in that the plate boundaries seldomcoincide with continental boundaries.

Stated very briefly, the plate tectonics conceptholds that new crust is constantly beinggenerated along mid-ocean ridges; hot moltenmaterial rises from the underlying mantle, cools,and is forced aside by new molten materialcoming from the depths. The plates are inconstant movement, the principal direction beingat right angles to and away from the center of themid-ocean ridges. On the opposite sides, theplates collide to form mountains, or one plate

Map showing the plate structure of the Earth. At subduction zones (heavy dark curves) such as the deeptrenches ringing the Pacific, the leading edges of the plates plunge downward to be consumed in the mantle.The mid ocean ridges are shown by the dark segmented lines. Along them the mantle wells up and solidifies asthe ocean floor spreads. Plates rub edge to edge along transform faults (thin curved lines). The dots mark thelocation of earthquakes that have been recorded during the last 20 years.

edge may be drawn below another at the deep seatrenches in what is called a subduction zone.Thus, along their boundaries, the plates eithermove parallel to one another, move apart (as atspreading centers) or converge (as at subductionzones). According to today's model, the presentspreading cycle started about 200 million yearsago, at which time the continents were essentially one land mass that split apart along what isnow the mid-Atlantic ridge. Since then thecontinents have been moving apart at about twocentimeters a year.

The plate tectonic concept has enormouspromise in explaining the origin of earthquakes,volcanoes, faulting, and mountain building withresulting implications for natural disasters,energy resources, and the emplacement ofeconomically valuable concentrations ofminerals and hydrocarbons. The general recognition of the potential impact of this "revolution inearth sciences" led to the concept of an intensiveinternational program to study the basicmechanism of earth deformation-the Inter-

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national Geodynamics Project (IGP).The IGP is an international program of

research on the dynamic processes that affectand have affected the earth. A major goal of theIGP is to delineate the internal forces that causethe horizontal motion of the plates, as well as thevertical movements of large parts of the plates,and ultimately to understand the mechanismsthat give rise to these forces.

The IGP is coordinated by the InterunionCommission on Geodynamics (ICG) establishedby the International Council of Scientific Unions(ICSU) at the request of the International Unionof Geodesy and Geophysics (IUGG) and theInternational Union of Geological Sciences(IUGS), with the provision for active participation of all interested ICSU unions and committees. There are now 52 countries participatingin the IGP with the realization that the platetectonic model is a global one, and that acoordinated effort among all parties involvedwill achieve greater and more rapid progressthan isolated individual efforts.

SOCIETAL BENEFITS FROM GEODYNAMICS STUDIES

Man's safety from natural hazards and man'sprosperity are closely linked to his understanding of large-scale geodynamic processes occurring at or beneath the earth's surface. Earthquakes; volcanoes; concentrations ofhydrocarbons, minerals, and geothermal heat;and mountain ranges are all manifestations ofsuch geodynamic or tectonic processes. It hasbeen known for some time that tectonic activityon a global scale is concentrated in very narrowzones but no rationale for the concentration of anumber of seemingly unrelated phenomena wasavailable until the advent of plate tectonics. Nowthe majority of the narrow zones of tectonicactivity are regarded simply as the network ofpIa te boundaries covering the surface of theearth.

Earthquakes

Almost 90 percent of the world's earthquakesoccur along these boundaries. Two such zonescross the United States. One extends from theCulf of California to Cape Mendocino (north ofSan Francisco) and includes the sites of the 1906San Francisco and the 1971 San Fernando earthquakes.

The second zone extends from southeasternAlaska through the Aleutian island chain andincludes the Aleutian trench, which is the site ofmany deep focus earthquakes. On land this zoneincludes the site of the large earthquake nearAnchorage in 1964. Many of the narrow earthquake zones cross densely populated regions,e.g., the Pacific Coast of the United States, Japan,and areas bordering on the Mediterranean Sea.Some 500 million people are exposed to personaldanger and damage to personal property in theseseismic risk areas. Perhaps more than any othergeophysical hazard, major earthquakes are likelyto produce almost complete social disruption inmodern urban areas. The vital technologies of acity both above and below ground may beshattered. To compound the problem, earthquakes may trigger secondary events such asfires, tsunamis, landslides, or floods, whichcommonly cause more damage and loss of lifethan the earthquakes themselves.

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The possibility of predicting and, to someextent, controlling earthquakes, has been greatlyenhanced by the plate tectonics concept. But, inorder to achieve such capabilities, a betterunderstanding is needed of the mechanics ofearthquakes and of the forces responsible for thestress accumulations. The dynamics of the platemotions is a crucial factor.

Certainly, a better understanding of themechanisms behind crustal movement and thestate of stress in the interiors of plates isessential before we can venture any effort atearthquake control. Results of several recentexperiments at the Rocky Mountain Arsenal andat Rangely, Colorado have indicated that minorearthquake activity can be initiated by pumpingnuid under pressure down a borehole so that itrelieves the stress at depth on a pre-existingfault. The activity can be stopped by withdrawing the fluid. This limited experience suggests thepossibility of control on a large active fault zonesuch as the San Andreas. Once the details of thes tress distribution at depth and the mechanism ofmovement along the fault are reasonably wellunderstood, a program of control by fluidinjection might be achieved whereby the storedstrain energy on the fault is released by inducinga number of small and relatively harmlessearthquakes.

A better understanding of the detailedmechanisms of crustal movements in fault zoneswould also be of great value in predicting groundmotion from anticipated earthquakes at potentialconstruction sites near or remote from the faultzones. Decisions of great societal and economicimportance should be based on such predictions,e.g. the siting of nuclear reactors, oil pipelines,aqueducts, dams and reservoirs, hospitals, andpublic transit systems.

Although most major earthquakes are alongplate boundaries, the interiors of plates are notimmune. In the North American Plate there havebeen major earthquakes in the vicinity of Boston,Massachusetts (1755); at New Madrid, Missouriin the central Mississippi Valley (1811 and 1812);at Charleston, South Carolina (1886); and atHebgen Lake, Montana (1959). Indeed, most of

Seismic Risk Map of the United StatesAreas of earthquake damage in historic times. Note that of the several areas of major damage only coastalCalifornia is associated with one of the plate boundaries.

the U.S. has some risk of seismic disturbance.The so-called intraplate earthquakes posespecial problems to be addressed bygeodynamics research because their relationshipto the horizontal movements of the plates is notobvious. Although intraplate earthquakes arerarer than earthquakes on plate boundaries, thelong term risk, in terms of property damage andloss of life, is comparable. This is because thecrust in the interiors of most plates is much moreuniform and homogeneous than at the boundaries. Thus it is a more efficient propagator ofearthquake disturbances and a given magnitudeintraplate earthquake will usually have a muchlarger area of high intensity and damage than oneof equal strength along a plate boundary.

Volcanoes

Volcanic activity is a surface manifestation of

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deep seated geodynamic processes. Its impact onman involves not only potential hazard but alsopotential benefit. The hazard of volcanic eruptions is of real concern; some 200,000 people havebeen killed by volcanoes in the past 500 years.Specific hazards include lava flows, pyroclasticflows, ash falls, volcanic mudflows, and floods,as well as a number of volcanically generatedevents such as tsunamis, forest fires, and debrisavalanches and landslides. Volcanic hazard issignificant in three major areas of the UnitedStates: Hawaii, the Cascade Range of the PacificNorthwest, and Alaska. The potential for loss interms of property damage, injury and loss of life,and social disruption appears to be increasingbecause of significant population growth andurbanization in all three major hazard areas. Thedevelopment of energy resources in Alaska andthe Pacific Northwest is magnifying the losspotential.

oI

SEA lEVEL

6000

50km.I

OCEAN BASIN

CRUST AND SEDIM

COLD MANtlE

CONTINENT

Volcanoes and Plate BoundariesA schematic cross section of a convergent plate boundary. As the oceanic plate moves from left to right, it isforced under the continental plate. When the upper part of the oceanic plate reaches to about the 1500°isotherm partial melting occurs and the magma rises to form volcanic mountains at the surface. Volcanoes arealso characteristic of the spreading centers or divergent plate boundaries.

As withearthquakes, volcanic activity is mostcommon in the tectonic zones that characterizethe plate boundaries. A better understanding ofthe geodynamic processes involved at plateboundaries is a necessary precursor to a betterunderstanding of a volcanic system, and anyhoped for eruption prediction.

Volcanoes contribute to man's well being inseveral ways. Soils derived from volcanicmaterial are extremely fertile. Volcanicemissions of rock and gas are sources of pumice,ammonia, boric acid, and carbon dioxide. Thethermal energy of volcanoes is being put to moreand more use. Many homes in Iceland are heatedby hot water tapped from volcanic springs.Geothermal steam associated with sites of recentvolcanism is being exploited as a source ofelectricity in New Zealand, Italy, the UnitedStates, Mexico, Japan, and the U.S.S.R.

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Natural Resources

Recent shortages and embargoes havehighlighted the need to understand the naturalprocesses that have produced petroleum, coal,metals, and other earth resources, such asgeothermal heat, that are essential to the Nation'stechnology. Plate tectonics is clearly related tothe formation of oil and mineral deposits. Theformation of oil and gas reservoirs appears tohave been determined to a large extent by thehistory of plate movements over the past 200million years. For example, long-term verticalmovements, which are related to geodynamicprocesses at depth, have resulted in sedimentfilled basin troughs that are important sources ofhydrocarbons. Almost nothing is known aboutthe forces that cause these vertical movements,despite their great economic significance. A

The Offshore Petroleum Potential of South AmericaAlong the east coast of South America are elongated basins filled with sediments that mayrange back to the time when South America and Africa split apart. These basins are a primetarget in the search for oil and natural gas.

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better understanding of such forces could improve our techniques for petroleum exploration.The total amount expended by U.S. companiesfor petroleum exploration is about $4 billion peryear. A modest increase of 1 percent in theefficiency of this effort, through better understanding of basic geodynamic processes,would amount to some $40 million per year.

It is equally true that mineral deposits are notrandomly distributed, but are related to past andpresent tectonic zones. The type of are presentand where it is located depends principally ontectonic history of the zone. A particularly clearexample is the copper sulfide deposits on theisland of Cyprus. The copper sulfide are occurs ina distinctive sequence of rocks, called anophiolite sequence, which is now thought to be alargely unaltered piece of oceanic crust thrust upwhen Cyprus was formed. The minerals itcontains are thus characteristic of those formedat mid-ocean ridges. Most of the mineral depositswith easily recognizable surface features have

been found. Future success in mineral exploration will require a sophisticated approach thatincludes an understanding of the relationshipbetween mineral deposits and the underlyinggeodynamic phenomena responsible for theirorigin.

Geothermal heat as a natural resource has beenexploited for centuries in areas of easily identified surface manifestations such as steamvents, hot springs, and geysers. However, thebroader picture of the flow of matter and energywithin the earth is one of the principal goals ofthe Interna tional Geodynamics Proj ect. Anunderstanding of deeper patterns of heat distribu tion, with little or no surface expression,will also be essential to the exploration anddevelopment of geothermal resources in the nexttwo decades. The plate tectonics concept andknowledge of the physics of flow of fluidsthrough permeable rocks will be valuable guidesto these exploration and development efforts.

OCEAN

50 KM

OCEANIC SEDIMENTS (LAYER) WITH MErALRICH HORIZON AT THEIR BASE

COPPER CONCENTRATIONSIN OCEAN IC CRUST

OCEAN RISE(S ITE OF M ETAL-R ICH

EXHALATIONS)

PORPHYRY COPPER DEPOSITS

VOLCANIC CHAIN

700 KM

A Possible Model for Porphyry Copper OresMagmas rising at the ocean spreading center (divergent plate boundaries) give off hydrothermal solutions richin copper, iron, and other transition metals. These precipitate and are incorporated into the basalt sedimentsjust above the lavas. When these metal-rich sediments are later forced down in a subduction zone at aconvergent plate boundary, and are partially melted (as shown in the previous illustration also) the copper isagain reconverted and migrates upward in hydrothermal solution to form large ore deposits like those of theAndes Mountains.

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HISTORY OF THE INTERNATIONAL GEODYNAMICS PROJECT

Rapid developments that resulted in newconcepts of global tectonics were taking place inthe earth sciences in the early and middle 1960's.These advances took place during the period ofthe International Upper Mantle Project-a discipline oriented program directed primarily atunderstanding the structure of the earth's interior. The exciting new concepts that emergedsea floor spreading and plate tectonics-caughtthe fancy of scientists all over the world. It wasinevitable that means to exploit these fruitfultheories would be actively explored.

The beginnings of the In terna tionalGeodynamics Project (IGP) can be traced to aninformal meeting of the Geophysics ResearchBoard (GRB) of the National Academy ofSciences in March 1968. The Chairman, MerleTuve, advocated an international effort, with thehypothesis of sea floor spreading as the focus,which would have a revolutionary impact onalmost all earth science disciplines.! These ideaswere approved by the Council of the AGU inApril 1968 who directed that they be transmittedto the International Union of Geodesy andGeophysics (IUGG). Later in the same month, theGRB adopted a similar resolution urging thatIUGG and the International Union of GeologicalSciences (lUGS) take prompt action to organize aprogram under ICSU sponsorship.

The GRB initiated correspondence with thetwo relevant international unions, IUGG &lUGS. Both reacted favorably to the proposal andinitiated discussions of it at their executivecommittee meetings in the summer of 1968. Thetwo committees reached agreement on finalwording and transmitted the proposal to theGeneral Assembly of ICSU in the latter part ofSeptember 1968. ICSU accepted the proposal inprinciple but requested the unions to prepare amore detailed statement of the nature of theproposed program. The unions then appointed anad hoc committee to be chaired by Prof. Charles L.Drake, composed of three members nominated byeach of the unions. The committee held twomeetings-in Paris (February 1969) and in

1 Transactions of the American Geophysical Union, Vol. 49,No.6, June 1968.

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London (May 1969), and produced a documententitled Report of the Ad Hoc Committee on theLong-Range Program of Solid Earth Studies.

This report, calling for a program entitled, "TheGeodynamics Project" was the subject of aninformal meeting convened in Madrid inSeptember 1969 during the General Assembly ofthe International Association of Seismology andPhysics of the Earth's Interior (IASPEI)International Association of Geomagnetism andAeronomy (IAGA), which was held to give theofficers of the unions a chance to discuss theproposed program with a representative group ofinterested scientists. The report, which authorized the creation of an interunion Commission onthe Geodynamics Project (ICG), was accepted bythe Executive Committee of ICSU in October1969. ICG was to consist initially of a bureau ofseven, a president agreed to by the two unionsand three nominees each from the two unions.Membership of the bureau was approved by theofficers of ICSU in February 1970. It held its firstmeeting in Flagstaff, Arizona, July 1970.

The recommendations and constitution of theICG were approved by the General Assembly ofICSU in September 1970, following which ICSUcalled upon the countries to develop programs ofparticipation in the Geodynamics Project. Tenworking groups of the ICG were established bythe bureau at its meeting in London in 1971 andimplemented at the IUGG General Assembly inMoscow in August 1971. These working groupsare problem-oriented; some deal with regionalproblems, some with global problems. Most ofthese working groups have been very active indeveloping plans and symposia. They haveprepared a series of frontier reports that areintended to assess progress to date in theirrespective problem areas and to indicate the mostfruitful direction for future research during theremainder of the Geodynamics Project.

The ICG has met annually since its initialmeeting in July 1970 as follows: LeidenNetherlands, March 1971; Moscow, August 1971;Montreal, August 1972; Lima, Peru, August 1973,Zurich, August 1974; Grenoble, France, August1975. At each of the meetings, beginning in 1972,there have been several symposia co-sponsored

by the Geodynamics Commission. The largestnumber of such symposia took place at themeeting in Grenoble in August 1975. In keepingwith the constitution of the Commission, therehas been a regular rotation of membership of theofficers of the Commission. The President in 1970through 1975 was Prof. Charles L. Drake whowas also the Chairman of the U.S. GeodynamicsCommittee. The new President is ProfessorAnton Hales of Australian National University,Canberra. There have been three GeneralSecretaries: Xavier Le Pichon, 1970-1972,Frances Delany, 1972-1975, R.D. Russell, 1976onwards.

The U.S. Geodynamics Committee of theNational Academy of Sciences began its workearly in 1970. The results of the Committee'sinitial thinking were published in the Transactions of the American Geophysical Union, May1971. After preparation of its initial document,the U.S. Geodynamics Committee called upon 14working groups involving some 170 scientistsdrawn from the academic community, government, and industry to assist in developingrecommendations for the program; sent drafts forcomment to correspondents (designated by thedepartment chairmen) in more than 100geoscience departments throughout the UnitedStates; consulted with those Federal agencies

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most likely to be interested in participating in theprogram; and received strong endorsement forthe direction of its planning from 9 majorgeoscience societies. The result of thesedeliberations was the issuance in 1973 of a majorreport, U.S. Program for the GeodynamicsProject: Scope and Objectives.

The geodynamics of the Americas plate isnaturally a principal focal point of the U.S.program. Thus. a significant step was theorganization of a meeting of Chairmen ofGeodynamics Committees of the countries of thewestern hemisphere in Brazil, March 1973. Othermeetings sponsored or co-sponsored by thegeodynamics commission closely related to theAmericas plate were: Buenos Aires, Argentina,October 1970; Flagstaff, Arizona, July 1970;Montreal, Canada, August 1972; Lima, Peru,August 1973; Mexico City, June 1973; Santiago,Chile, September 1974; Reykjavik, Iceland, July1974; Vancouver, Canada, August 1975; SaoPaulo, Brazil, October 1975.

The following time period for the lGP wasrecommended at the meeting of the Chairmen ofGeodynamics Committees of the Americas inMarch 1973 and was approved by the lCG and byICSU in September of 1973: 1971-1973 as theperiod of planning and initiation; 1974-1979 asthe period of active research programs.

WHY IGP IS TIMELY

International programs such as IGP, that aresponsored by one or more of the 17 disciplineoriented Unions of the International Council ofScientific Unions (ICSU) and approved by thegoverning council of ICSU, usually have severalcommon characteristics. These include: (1) theglobal character of the science (for example themagnetosphere) that usually requires real-timeobservations and coordination of many nationswith similar data-gathering techniques, (2)recent major discoveries in the sciences ( as theplate tectonics theory) or in the observingtechniques (for example satellite monitoring)that represent new opportunities for participants, and (3) major societal needs that wouldbenefit from new scientific or technicalknowledge (for example water resourcesresearch).

An international program provides, at the costof many man-years of scientific planning and theorganization of many symposia and workshops,cooperation between larger and smaller nations,the timely sharing of significant results, theelimination of costly duplication of major fieldefforts, and the establishment of data centerswhere specifics of the results of field proj ects arewidely distributed. International programs arealso a means of increasing the scientific manpower that is marshalled to a scientific disciplineand providing for the identification of majorobstacles to the progress of the subdisciplines.

Two specific reasons for the timeliness of theIGP are (1) international concerns of the futuredepletion of many of the earth's nonrenewablematerial resources: the hydrocarbons andminerals, and the concomitant need for betterinformation on geothermal heat as an independent source of energy; and (2) the political

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problems dependent on an equitable international solution within the United Nations andthe Law-of-the-Sea conferences.

The plate tectonics theory provided the firstmajor breakthrough as a working hypothesis forthe horizontal movements of the earth's crust andthe sources and sinks of the crust and uppermantle material. It offers some rationale for thespecific locations of petroleum fields, the concentration of ore bodies, and of geothermal heatsources. The study of geodynamics provides amajor source of the basic information needed forthe optimum exploration of these earthresources.

The plate tectonics theory would undoubtedlyhave been delayed for a number of years were itnot for the pioneering work of a relatively fewdedicated scientists who studied thecharacteristics of the oceanic crust: the detailedocean floor bathymetry, the character of theocean sediments, and the geophysical parametersof the oceanic crust. A decade or two ago, theoceans had few political boundaries outside the3-mile zone, but today, with the growing realization of the importance of the oceans as a sourcefor many of man's future requirements, the"ownership" of ocean areas has become a majorpolitical problem for the United Nations.Regardless of the outcome of the Law-of-the-Seaconferences, scientific exploration of a majorpart of the world's oceans will depend largely oninternational cooperation and goodwill betweennations. This cooperation can be best initiatedand extended by participation in internationalprograms, such as the InternationalGeodynamics Program, whose objectives havelong-term mutual benefits.

QUESTIONS FOR GEODYN1AMICS TO ANSWER

Plate tectonics is a very attractive and persuasive hypothesis as a base for geodynamicsstudies because it apparently explains many ofthe earth's major features and molds them into asingle picture. Yet it is still barely a dozen yearsold, and many gaps and discrepancies need to beexplored before we either give it full credence orreplace it with a more-encompassing hypothesis.Among the important problems now needingattention and answers are (aJ the nature ofprocesses that act on the plates, both the platemargins and the interiors, (b J the history ofspreading and plate movement, and (c J the natureof the driving forces.

Nature of processes

Of the different plate boundaries, the divergingtype, i.e. the mid ocean ridges where new crust isformed, are probably the best understood. Yeteven these have knowledge gaps. Much of whatwe are learning about these zones continues tocome from standard oceanographic cruises, butmuch new information is being obtained from theuse of more sophisticated and expensive toolssuch as deeply towed instrument packages,ocean-bottom seismometers, and research submersibles. The recently completed field experiments of Project FAMOUS (French-

Topographic Model of the FAMOUS AreaA model of the area of the Mid-Atlantic Ridge where the French-American Mid-Ocean Undersea Study(FAMOUS) project took place. Many surveying techniques, including observations from deep mannedsubmersibles, were used to produce this model and label its features.

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American Mid-Ocean Undersea Study) are goodexamples. In this project, volcanic and tectonicprocesses associated with an active spreadingcenter have been directly observed from mannedsubmersibles. Despite these recent advances,there are still significant unexplained geological,geochemical, and geophysical variations thatexist along the axes of the mid-ocean ridges.These variations must be accounted for in anycomprehensive model of plate tectonics.

Converging plate boundaries are much morecomplex. When the colliding plates both carrycontinents near their leading margins, complexstructures such as the Himalayas, subparallelmountain ranges, and elevated plateaus areformed. When the convergence is betweenoceanic crust and continental crust, the oceaniccrust is usually subducted with the formation ofa deep trench and an island arc system. These arecomplicated geological structures and the

Divergent boundary

Plate BoundariesA&B-Divergent BoundaryMagma rises along a rift or spreading center, cools, and is forced aside by new magma coming from below. Therift may split continental crust (A), or oceanic crust (B).CaD-Convergent BoundaryC. At the zone of convergence one plate is of oceanic crust, the other (on the left) is continental. A subductionzone, trench, and volcanic and folded mountain chain are developed.D. Both plates carry continental blocks. As these collide, the structu res, both in the subduction zone and in themountains become exceedingly complex. Great nappe folds such as those of the Alps are common.

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primary process taking place, underthrusting,occurs at such great depth that it is difficult tomeasure. A better understanding of convergingplate boundaries is very important, for these arethe zones of volcanic and earthquake activitywith their far-reaching effects on the population.

As noted elsewhere, not all deformation takesplace at the plate boundaries. Important deformations, either large scale faulting or warping,can and do occur in the interiors of plates. Onerecord of large vertical movements is the thicksedimentary sequences of subsided basins wheremost oil and gas deposits are found. Othervertical deformations, often accompanied byvolcanism, are found in such areas as theColorado and Himalayan plateaus and in many ofthe continental shields. Nor are large verticalmovements restricted to continental crust; deepocean areas within plates have also undergonesuch deformation (e.g., the sediment-filleddepressions beneath the continental rises ofeastern North America and the deep sea floor eastof Florida).

Vertical movements, both in the interior ofplates and at their boundaries, control theoccurrence and distribution of many economically valuable mineral deposits. These deposits ofigneous and metamorphic origin require a historyof subsidence and subsequent vertical uplift tomake them accessible for exploitation.

The plate tectonics model in its present formmore readily explains horizon tal than verticalmovement. Perhaps vertical movement will befound to be caused by other dynamic processesoperating independently of those that are nowcausing the horizontal movements. Nevertheless,if the plate tectonics model is to have generalvalidity it must be able to explain all majorcrustal movements, oceanic and continental,vertical and horizontal.

History of spreading

For a full understanding of how the earthbehaves as a system, it is crucial to establishwhether plate tectonics has been an integral partof the dynamic history of the earth from thebeginning or whether it has appeared duringsome later stage of the planet's history. Thecurrent spreading cycle can only be extrapolatedback about 200 million years, when the continents as we now know them were joinedtogether in one large land mass, called Pangaea.As no part of the oceanic crust is older than this,

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evidence for prior plate movement will have to besought on the continents; the criteria forrecognizing old plate boundaries on land are notyet fully developed. Perhaps one of the bestindicators is the location of the mineral richgreenstone belts, volcanic rocks resemblingthose of modern island arcs. Such greenstonebelts are found in Canada, Australia, SouthAfrica, and other areas of very old crust. If theseold greenstone belts are indeed relics of ancientisland arc subduction systems they constituteevidence of plate tectonic activity prior to thebreakup of Pangaea. This is not a universallyaccepted hypothesis however, and much morework needs to be done.

Driving force

The most fundamental problem to be addressed by the IGP is the question of the drivingmechanism that keeps the plates in motion. Thisdriving mechanism is the source of the forcesinvolved in all the horizontal and verticalmotions we observe in the lithosphere and untilwe establish its nature a complete description ofthe geodynamic processes within a planet isbeyond our capabilities. There are severalpromising lines of research to be pursued.

It is generally agreed that the interior of theearth has unstable zones. Three kinds of instability important for a general theory ofgeodynamics are: density inversions, fusion, andsolid-solid phase transformations. Thetheoretical boundary-value problems associatedwith these zones of instabilities will be formidable and will require quantum mechanics andlattice theory to explain the nature of fusion andthe nature of solid-solid phase transformations.

In the laboratory, tests of representativemantle mineral assemblages at very highpressures and temperatures are needed to determine shear velocities in the vicinity of phasetransformations and the creep properties of theassemblages-a measure of the relative fluidityof the mantle. The volume capacity of present daylaboratory test facilities must be increased todetermine these properties.

'Nhen phase transformations are incorporatedin a geodynamic theory it is important to knowthe time scale of the transformation and to knowthe energy exchange involved. Experimentalwork on the kinetics of phase transition is justbeginning. There may be phase transitions in theearth that are important to geodynamics but

The Drift of ContinentsThe disposition of the continental crust on the surface of the world during the present spreading cycle. About200 million years ago the continents, which were at that time joined together in the supercontinent Pangaea,began to split and drift apart. A principal split was along the rift zone that today forms the Mid-Atlantic Ridge.The spreading continues and today's picture is but one frame in a long motion picture.

proceed so slowly in the laboratory that they areunobservable.

Temperature is probably the most important

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parameter controlling the dynamics of motion inthe earth's interior. The interior of the earth isessentially a heat engine, involving heat transfer

by large-scale transport of matter, that providesthe power to drive the plates. Heat from phasetransformations of mantle material and heatfrom radioactive decay may cause thermalinstabili ties that would influence the drivingforces.

Surface heat flow measurements are not asensitive indicator of temperature at depthbecause a major part of the anomalous surfaceheat flow can be explained in terms of heattransported laterally away from the oceanspreading centers. Seismic shear-wave velocitiesdepend on the temperature and so can be used asan indirect indicator of the thermal state of theearth's interior. More laboratory work must bedone to determine equations of state, includingthe shear properties of matter under temperatureand pressure, especially near the melting point.

A number of explicit suggestions have beenmade for the driving forces, such as convectioncells, mantle plumes, gravity sliding from themid-ocean ridges, and gravity pulling platesdown at trenches. Much of the work being doneon these explicit mechanisms is theoretical. Moreconstraints from geological evidence are neededthat can be placed on mantle motions-such as

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the patterns of volcanic activity, the distributionof trace elements, and distribution of mantletype rocks on the earth's surface.

In summary, a few of the important questionsto be answered during the InternationalGeodynamics Project by increased effort in theresearch areas mentioned above are:

1. What is the state of stress in the boundaryareas of the plates that manifests itself in thehorizontal movements that we are beginningto understand?

2. What is the state of stress in the plateinteriors resulting in vertical movementsstill not understood?

3. What dynamic system operating in theearth's interior is producing these stresses?

4. What are the past locations of the earth'srotation axis relative to the main plates of thelithosphere and the location of these platesrelative to each other?

5. Does plate tectonics represent a new andunique episode in the earth's history or has itbeen an integral part of the dynamic historyof the earth from the beginning?

RESUME OF FEDERAL ACTIVITIES IN IGP

In order to obtain a reasonable estimate of theamount of funds presently being allocated forgeodynamics-related activities within the U.S.Federal Government, it was first necessary toadopt a set of definitions of geodynamicsacceptable to the Committee so that figures fromthe various agencies will fall within comparableguidelines. The definitions adopted by the ad hoccommittee were taken primarily from the NASreport U.S. Program for the Geodynamics Project. These are divided into two separatecategories-those activities concerned generallywith the interior parts of the earth: the lowercrust, mantle and core, and those which involvethe lithospheric plates. The descriptions areincluded as Appendix I.

Part I, The Internal Processes and Properties,is divided into four parts: Dynamical Models,Geophysical Observations of Internal Processes,Physical and Chemical Properties of Mineralsand Mineral Assemblages, and Geological Constraints. This part includes research on thepattern of mantle motion, energy sources withinthe earth that are responsible for mantle motion,temperature fields, geothermal history of theearth, motions and dimensions of the interior ofthe plates, the method of plate coupling to themantle, the phase and mineralogical changestaking place in the interior of the earth, meltingphase changes, and the generalized equation ofstate. Most of these activities are eitherlaboratory studies of selected material, data fromvarious geophysical measurements, andgeological character of mantle material foundnear the surface through volcanic activities orsurface erosion.

Part II, Boundaries, Movements, and Structureof Lithospheric Plates, is rather straight forward.A considerable amount of data on boundariescomes from marine studies, and many platemovements are derived from recent magneticlineations found near the spreading centers, orfrom independent observations of motions usingextraterrestrial sources as references, or studiesof recent fault displacements. This category alsoinvolves the remeasurements of major networksof control stations in the U.S. The past movement

16

of plates depends to a large extent onpaleomagnetic measurements and extension ofthe history of magnetic reversal, and geologicalinferences of fault motions. A final categoryincludes the accretions and composition of theplates, such as the characteristics of materialadded at the margins.

On page 22 is shown a table of agencyexpenditures in FY 1974,75 and 76 by the variouscategories of geodynamics defined above. Thetwo agencies most responsible for geodynamicsexpenditures are the U.S. Geological Survey andthe National Science Foundation with $26.7Mand $21.1M for FY 1976, respectively. At a lowerlevel are the composite figures for the fourcontributing offices of DOD $7.9M, followed byNASA $6.1M, ERDA $4.0M and Commerce$3.0M. For the major programs involved withlarge logistic components, which are only partially geodynamics related such as NASA'ssatellite studies, NSF's Ocean Sediment Coring.Program, and NOAA's network for horizontaland vertical control, an estimated fraction of thecost related to geodynamics has been made.

Inasmuch as the figures for FY 74 are actualallocations, while those for FY 75 and FY 76 areestimates, the increase shown for the 75 and 76figures over 74 may be somewhat in error. Mostof the increases are within the USGS, and relateto their relatively new responsibilities in earthquake research. Several years of actual figureswould be needed to get a reliable estimate ofincreased funding to geodynamics.

The brief description of agency activities bythe geodynamics categories, outlined below, issupplemented by a more extensive description ofthe work by agencies, Appendix II. Thegeodynamics activities consist largely of theindividual efforts of many scientists. These arein-house activities for some agencies, such as theUSGS, and at the universities and other nonprofit institutions, as in the NSF. Major singleprograms are relatively few and occur mainlywhere agency mission work is closely related togeodynamics objectives, such as NASA'ssatellite studies and NOAA's vertical controlnetworks.

Federal Agency* Activities in IGP

Figures with Agency titles refer to FY 76 Estimates.

I. Internal Properties and Processes

A. Dynamical Models

AFGL (120K)-Obtain more accurate modelsfor the gravitational field by better theoriesand more precise measurements. Predict theresponse of the earth model to dynamic andstatic loading of the crust.

ERDA (105K)-Modeling of geologic processesdirected at understanding the emplacementof plutons and the thermal state of theirenvironments.

NSF (271K)-Modeling studies of the earth'score and convective motions in the earth'smantle and at the crust-mantle boundary.

USGS (1,090K)-Studies of dynamic modelingof precursor phenomena as part of theEarthquake Hazards Reduction ProgramComputer modeling offault displacements toachieve an understanding of faultmechanisms and related effects-Modelingof selected well-known geothermal systemsto study the mechanism by which water andheat are transferred in geothermal systemswithin the crust.

B. Geophysical Observations of InternalProcesses

DOC (630K)-Trans-Atlantic Geotraverse(TAG), an intensive geophysical investigation of a corridor about 285 km. wide fromCape Hatteras to Mauritania to study the

*DOC-Dept. of CommerceAFGL-Air Force Geophysics LaboratoryARPA-Advanced Research Projects Agency (DOD)NAVOCEANO-Navy Oceanographic OfficeERDA-Energy Research & Development AdministrationONR-Office of Naval ResearchNASA-National Aeronautics & Space AdministrationNSF-National Science FoundationUSGS-U.S. Geological Survey (001)

17

structure of continental margins, axialprocesses of the mid-Atlantic Ridge, andevolution of oceanic crust.

ARPA (220K)-From seismic events, studyproperties of the crust and upper mantleunderlying the Aleutian Island region, midAtlantic Ridge, western U.S., central Asia,Iran, and the Arctic Basin.

ONR (923K)-Marine gravity studies of shortand long-term wave anomalies by investigating gravitational effects of primarytectonic features of the ocean floor-Seismicand electrical studies of crust and uppermantle characteristics.

ERDA (885K)-Investigate physical andchemical state of the earth's upper mantle bystudying specimens derived from the mantleor analogous synthetic materialsDetermination of geothermal gradients andthermal conductivity from drill holes toobtain heat flow-Evaluation ofaeromagnetic data to determine depth toCurie point.

NASA (2,900K)-From existing knowledge oflunar motions, support investigations ofearth's rotation and polar motion-Moreprecise description of the earth's gravityfield from measurements of oceantopography taken by GEOS-3.

NSF (3,495K)-Earthquake seismology forstudy of internal processes-Geothermalstudies-Seismic studies of internalcharacteristics by controlled explosivesExperiments with the ocean bottomseismograph for earthquake monitoringResearch on telluric, magnetotelluric,electro-magnetic induction, and electricalresistivity methods for crustal and mantleproperties-Marine gravity observationsfrom oceanographic vessels.

USGS (8,550K)-Microearthquake studieswith dense arrays of short-periodseismographs for three-dimensional mapping of active fault zones-Refractionseismic surveys to determine structuralelements of the crust and upper mantleInformation on thermal regime of earth'scrust and upper mantle through heat flowmeasurements-Analysis of thermal infrared images over broad areas for surfaceindications of heat flow-Magnetic andgravity surveys to identify zones ofanomalous magnetization and density in thecrust and upper mantle-Detection of zonesof anomalous conductivity in the subsurfaceby various electrical and electromagnetictechniques-Investigations of the deepstructure of the continental shelf and slopeby continental geophysical surface mergedwith marine geophysical researchDistribution of magnetization and electricalconductivity within the earth by orbitingsatellite magnetometers which record broadwa ve-Iength anomalies-Studies ofvariations of hydrodynamic processesoperating in the earth's core by micropulsation data.

C. Physical and Chemical Properties of Mineralsand Mineral Assemblages

DOC (126K)-High pressure studies includecalibration of pressure scales, continuedwork on an ultra-high pressure cell, andextension of the pressure scale.

ONR (95K)-Physical properties of the solidearth by electric resistivi ty of minerals atelevated pressures and temperaturesEffects of microfractures on physical properties of rocks.

ERDA (1,301K)-Construction of test facilityat LBL to test rock samples to 400°C. and1,000 bars-Use of explosive shock wavesand static high pressure devices at LASL toextend high P-T ultrasonic and equation ofstate studies-High P-T phase equilibriastudies of individual pure mineral phasesPhysical and chemical properties of silicatemelts-Static deformation of minerals androcks to permit accurate prediction ofresponse of the earth's crust to stress-Rockmechanics computer code development.

NSF (2,423K)-Investigations of sonic velocity, flow measurements, development of

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microcracks, shear strength and electricproperties of rocks under high P-T byultrasonics, shock and static compressionUse of high P-T equipment for geochemicalstudies such as equilibrium and masstransfer among minerals and aqueoussolutions, the diffusion kinetics of traceelements, mineral crystal chemistry, andthermodynamics of ionic interactions.

USGS (1,650K)-Measurement of the physicalproperties of rock-forming minerals todetermine how the thermal and stresshistories of minerals affect their propertiesIgneous petrology directed toward understanding magmatic systems-Phaseequilibria studies of multicomponentsystems-Thermodynamic properties ofselected minerals-Research in isotopicgeochemistry, including light stable isotopesand radiogenic isotopes-Neutron activationstudies-Mechanical, electric, and thermalproperties of rock samples to 1,000°C and 10kilobars.

D. Geological Constraints

ERDA (965K)-Field studies of igneousterrains at LASL to understand the implacements of magmas from depth-Thedynamics and thermal problems associatedwith pluton emplacement and volcaniceruptions by field studies of the Rio Grandrift, the andesite volcanoes of the Cascadesof northern California and field studies ofactive volcanoes-Studies of lava, volcanicrocks, and xenoliths from kimberlite pipesand andesites-Observational andanalytical geochemistry and petrology.

NSF (3,S99K)-Geology, geochemistry andgeochronology of volcanic rocks fromseveral geographic areas, and of the mantleand deep crustal rocks exposed at thesurface-Studies of the basalts obtainedfrom the OSCP and rocks recovered from theMid-Atlantic Ridge in the FAMOUSExperiment-Stedies of the geochemistry,petrogenesis, and geochronology of Antarctic rocks from the Dry Valley Drilling Project.

USGS (5,000K)-Petrologic and structuralstudies of volcanic, sedimentary, andplu tonic rocks to determine tectonic historyof the western margin of the North Americanplate-Studies of volcanic rocks and

associated plutons in the San Juan andAbsarka Mountains and in central Idaho todetermine the chemistry of the igneous rockserupted through the North American plateDetailed studies of ankaramites in Hawaii,caldera deposits in New Mexico, and basaltsin the Pacific Northwest to estimate thedepths of phenocryst formation andcrystallization history in large volumes ofsilicic melt-Studies at the Hawaiian

Volcano Observatory of the generation andmovemen t of magmas-Studies in Alaska ofisland arc volcanic rocks and of ophioli tecomplexes indicative of subduction along themargins of the North American plateStudies in southwest Oregon to determinehow podiform chromite-bearing ultramaficand mafic bodies were scraped off theoceanic plate and juxtaposed on the NorthAmerican plate.

II. Boundaries, Movements and Structure of Lithospheric Plates

A. Present Plate Boundaries

ARPA (150K)-Study of seismicity of MidAtlantic Ridge-Relation of seismicity andtectonics in the Indus Suture zoneCharacterization of source properties ofearthquakes in the case of continent-tocontinent collision to aid in the mapping ofpresent plate dimensions.

NAVOCEANO (1,3Z5K)-Detailedgeophysical survey of the GalapagosSpreading Ridge-Studies of the MidA tlan tic Ridge with near-bottom recordingmagnetometers-Aeromagnetic surveys inthe Arctic Ocean for details on theLomonosov Ridge-Geophysical survey ofthe Indian Ocean-Continued studies of theCayman Trough Spreading Center of theCaribbean Plate.

ONR (930K)-Geological and geophysicalinvestigations of the dynamics of thenorthwestern borders of the Pacific PlateStructure and tectonics of the Bay of Bengaland western Sundra Arc in the IndianOcean-Structure and interaction of theCocos and surrounding plates-Structureand seismicity of the Juan de Fuca Plate.

ERDA (470K)-Operation of a seismic networkin the Shumagin Islands near the tip of theAlaskan Peninsula, and a large apertureseismic array in the eastern Aleutian arc eastof Unalaska Island.

NSF (3,349K)-Geophysical studies of theboundaries and structures of the NazcaPlate, the eastern and southeastern parts ofthe Asian Plate and the western part of thePacific Plate-Studies of the tectonic evaluation of the South Kenya Rift zone-Detailedstudy of the Mid-Atlantic Ridge-Seismic

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measurements with Ocean BottomSeismometer.

USGS (1,510K)-Operation of the WorldwideNetwork of Standard Seismographs, 116sta tions in 69 countries, an essen tial sourcefor seismological data used in lac a tingearthquakes-Studies of topography andgeology of mid-Atlantic Ridge in the regionsouthwest of the Azores Islands with deepsubmersible craft.

B. Present Motion of Plates

DOC (1,Z95K)-Establish, maintain and adjusthorizontal and vertical geodetic controlnetworks over the U.S., including a specialGreat Lakes and Mississippi Valley levelingprogram in cooperation with the GeodeticSurvey of Canada-Establish horizontal andvertical networks across the San Andreasfault between Los Angeles and SanFrancisco-Operation of the zenith tubemeasurements of polar motion atGaithersburg, Maryland, where suchmotions have been observed over the past 75years-Maintain a gravity base networkacross the U.S.

ARPA (1,100K)-Studies of anomalouscharacteristics and causes of moderate tolarge earthquakes in the normally aseismicarea of eastern U.S. by an integration of allavailable data including sea level changesEarthquake focal mechanisms for thrustfaults.

ERDA (Z50K)-Electrical resistivitymeasurements to detect changes due totectonism within the San Andreas Faultzone.

NASA (3,ZOOK)-Tectonic Plate Motion proj-

ect will provide measurements of precisemotions between defined points, using bothlaser tracking and very long baselineinterferometry-The Lunar Ranging Experiment will utilize existing knowledge oflunarmotions and continuing range measurementsto support investigations on plate motionThe Geodynamic Experimental OceanSatellite (GEOS-3) project will provide,through measurement of ocean topography,an improvement in the description of theearth's gravity field, and in the variations ofsolid earth geometry-The LaserGeodynamic Satellite (LAGEOS) projectwill provide the capability of accuratemeasurements of earth's crustal motion.

NSF (17ZK)-Response of the earth to lateQuaternary ice melting-Earth tidestudies-Application of atomic clockinterferometry-Geophysical applicationsof long baseline interferometry.

USGS (1,480K)-Geodimeter surveys forhorizontal movements and level surveys forvertical movements are used to determineelastic strain accumulation and strike-slipalong faults and to detect premonitorystrains-Study of sea level measurementsfor possible use in determining crustal upliftor subsidence-Investigations ofseismomagnetic effects along western United States fault zones as an indirect meansof moni to ring crustal stress.

C. Plate Boundaries and Rates of MovementDuring the Past

ONR (9Z0K)-Study of marine magneticanomalies of ocean basins, including triplejunction of anomalies in south Atlantic andIndian Oceans-Regional magnetic field ofArctic Basin-Paleo-magnetic studies ofsediment cores.

NSF (4,757K)-Studies of cores obtained fromthe OSCP-Paleomagnetic projects dealingwith past plate movements-Geological andgeophysical studies in areas of plateboundaries-Studies of sediment corestaken from the Eltanin and from the DryValley Drilling Project in AntarcticaGeological studies in the Antarctic Mountains and the Antarctic Peninsula-Gravity,heat flow, and magnetic measurements in thecontinental margin of West Africa andeastern South America in order to construct

20

the various stages of the opening of the SouthAtlantic.

USGS (780K)-Refinement of geomagneticreversal times from radiometrically datedvolcanic and plutonic rocks-Study ofdecrease in amplitude of magnetic anomalystripes with increasing distance from thespreading axis-Research in geochronology,including investigation of the 40 Ar/39 Ar agespectrum dating technique-Study of use ofthermoluminescence as a dating tool foryoung volcanic rocks.

D. Plate Accretion, Composition and Structure

DOC (45ZK)-Measure sedimentary processeson the continental margin sedimenttransport system in the mid-Atlantic Bightand measure temporal changes of the sediment substrate.

ONR (65ZK)-Geological and Geophysicalinvestigations of interior features of thePacific Plate: Hawaiian Ridge, Emperor SeaMount, and Hess Rise-Properties of Layer2, defined seismically as the upper one or twokilometers of the crystalline oceanic crust,including thickness, velocity structure,topography, and magnetic properties.

NSF (3,Z4ZK)-Geological and geophysicalinvestigations of the East Atlantic continental margin-Geophysical study of continental margin of Argentina and BrazilSedimentary history of ocean basins fromstudies of the cores from the Ocean SedimentCoring Program-Structural development ofthe Southern Cordilleran orogenGeological history of continental accretionon Kodiak Island-Tectonics, evaluation andcrustal composition of the western IndianOcean ridge systems-petrochemical andgeochemical evolution of the central NorthAtlantic-science program of mid-AtlanticRidge, Project FAMOUS-Marine geologyand geophysics of the Sunda Arc-Geologyof the Lassiter Coast, AntarcticaGeological investigations in the PensacolaMountains, Antarctica-The structure andtectonic history of the northern limb of theScotia Arc.

USGS (6,600K)-Locate recently-active faultstrands within the San Andreas system anddetermine tectonic history along the activeplate margin-Analysis of intense folding

and faul ting in the Salton Trough northwardto the Mendocino Fracture Zone to determinethe location, direction and magnitude ofdisplacements-Geologic and Geophysicalstudies of the Oregon and Washingtoncontinental margin-Detailed mapping ofactive surface faults along coastal AlaskaStudy of the Tertiary and Quaternarygeology and biostratigraphy of the coastal

21

region, the continental shelf and the offshoreislands of western Alaska to determine therates of past and on-going coastaldeformation-Synthesis and compilation ofgeologic information on the Colorado Plateauto determine why this region escaped thedeformations that affected the Basin andRange Province to the west and the RockyMountains to the east.

Fiscal Summary of Geodynamics-Related Programs in Federal GovernmentFY 74, FY 75, FY 76

(In thousands of dollars)

NAVO-DOC· AFGL ARPA CEANO ONR ERDA NASA NSF USGS TOTAL

I. Internal Properties & ProcessesA. Dynamical Models 74 78 45 43 231 1,069 1,466

75 105 60 95 239 1,079 1,57876 120 50 105 271 1,090 1,636

B. Geophysical Observations 74 600 25 265 35 1,123 253 2,100 2,939 5,015 12,455of Internal Processes 75 165 25 170 20 1,078 540 2,200 3,236 8,496 16,030

76 630 50 220 10 923 885 2,900 3,495 8,550 17,763

C. Physical & Chemical Properties 74 130 91 795 2,006 1,349 4,371of Minerals & Mineral Assemblages 75 126 74 1,131 2,141 1,559 5,031

76 126 95 1,301 2,423 1,650 5,595

D. Geological Constraints 74 10 95 593 5,115 4,588 10,40175 7 30 765 6,814 4,901 12,51776 5 -- 965 3,899 5,000 9,869

'" II. Boundaries, Movements, &' Structure of Lithospheric Plates

'"A. Present Plate Boundaries 74 108 145 228 950 300 3,386 1,169 6,286

75 350 145 258 510 365 3,416 1,486 6,53076 10 150 1,325 930 470 3,349 1,510 7,744

B. Present Motion of Plates 74 1,321 362 36 18 1,800 197 1,110 5,00475 1,197 715 15 125 3,500 178 1,450 7,37076 1,295 1,100 -- 250 3,200 172 1,480 7,757

C. Plate Boundaries and Rates of 74 20 1,050 6 3,056 546 5,128Movement During the Past 75 30 770 25 4,096 750 5,671

76 30 920 25 4,757 780 6,512

D. Plate Accretion, Composition 74 680 40 -- 865 2,644 5,639 9,968& Structure 75 610 60 -- 800 2,631 6,444 10,654

76 452 60 57 652 3,242 6,600 11,163

TOTAL 74 3,199 143 772 329 4,219 2,008 3,900 20,024 20,485 55,07975 2,838 190 1,030 330 3,322 3,046 5,700 22,751 26,165 65,37276 2,973 230 1,470 1,427 3,570 4,001 6,100 21,608 26,660 68,039

• DOC Data Center (FY 74-$360K; FY 75 $390K; FY 76 $460K) not included in the DOC column but are added in the TOTALcolumn. Future reports will contain data center funding of other agencies.

INTERNATIONAL PARTICIPATION

Fifty-two countries have indicated their participation in the International GeodynamicsProject. The first 46 countries in the following listhave established national committees for theproject. The last six have nominated nationalcorresp onden ts.

*Argentina*Australia*AustriaBelgiumBoliviaBotswana*Brazil*CanadaCentral American

Regional CommitteeChile*Colombia*CzechoslovakiaDenmark*D.R.G.Equador*F.R.G.*Finland*FranceGhanaGreeceHungary*Iceland*IndiaIranIreland

IsraelItaly*JapanKorea*Mexico*NetherlandsNew ZealandNigeriaNorwayPoland*South Africa*Spain*Sweden*Switzerland*Taiwan*Turkey*United Kingdom*U.S.S.R.*U.S.A.VenezuelaYugoslaviaCubaIndonesiaPakistanPhilippinesRhodesiaThailand

Participating countries were requested toprepare reports on their national activities inGeodynamics for the IUGG General Assembly inGrenoble in 1975. Reports were received from 25countries (marked by asterisks in the above list),and others will be available in the near future.

The reports indicated a high degree of activityin many participating countries with interestingand relevant scientific results. The reports donot, in general, con tain fiscal information. Spain,however, did report a specific allocation for theGeodynamics Project at an annual level of$231,000 (plus significant logistic support fromthe Spanish navy) for a program concentrating

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on the geodynamics of the Western BeticMediterranean Range, the Canarian Archipelago,and the Iberian Plateau. The studies includeddeep seismic profiling. Similarly, Swedenreported a grant of $230,000 per year from theSwedish Research Council for two principalproj ects of an international and interdisciplinarycharacter; (1) the Caledonian Research Project,and (2) study of post-glacial earth movements.

Although fiscal data is not given, it is apparentfrom the reports of such countries as France,Federal Republic of Germany, Japan, U.S.S.R.,and others that expensive world-wide fieldprograms have been undertaken under the aegisof the program. The French, in addition to thewell-known FAMOUS project, have activeprograms in the Pacific Ocean, the AndesMountains, the Caribbean Sea, the Mediterranean Sea, and the Alps Mountains. The FederalRepublic of Germany has put special emphasison the Rhinegraben, the European plate, the AlpsMts., Mediterranean Sea, Red Sea, AfarTriangle,Indian Ocean, Iceland, South Africa and LatinAmerica. The Japanese have devoted 14 researchcruises to the investigation of the movement andstructure of the ocean floor of the Western Pacificand have similarly allocated large-scale andexpensive logistic support to a second programemphasizing studies of the movement andstructure of island arcs. The USSR has similarlarge scale expeditions, not only in the SovietUnion, but in Africa, Iceland and elsewhere.

Many countries have not received specialfunding for the IGP but have successfully puttogether meaningful programs by reprogramming and redirecting existing resources. TheCanadian 3rd report, for example, indicatessignificant progres s in 5 interdisciplinary areas;(1) global dynamics, (2) short term motions, (3)crustal evolution, (4) Phanerozoic fold belts andadj acen t oceans, and (5) the Canadian shield.Current activities are broadly distributed amongvarious Federal and provincial governmentagencies, universities, and mining and petroleumexploration companies.

Other countries, having limited resources,have inaugurated good programs by means ofinternational cooperation. Two examples are

Mexico and Colombia both of which haveemphasized cooperative programs with U.S.universities and institutions. The Mexicanprogram includes work in the Gulf of Mexico andthe Cocos Plate, a network of 8 seismic stationsaround the Gulf of California, 360 km. longseismic refraction profile, heat flow studies, andgeodetic studies. Similarly, the Colombians haveconcentrated on seismic refraction studies of thecontinental margin, oceanographic studies, andmagnetotelluric studies.

Most countries have tailored their programs tothe study of important geodynamic problemsthat can be uniquely studied within their ownborders or because of relevant experimental andtheoretical research practiced in those countries.The G.D.R. presented a broad program encompassed within two complex subjects; (1) development of a geodynamic model of the tectonospherein Central Europe, and (2) investigation of thedriving mechanism of geodynamic processes.They presented a bibliography of some 360 titles.The Turkish program is mainly focussed ongeological studies related to pIate tectonics of theeastern Mediterrannean, seismological studieswith emphasis on the N. Anatolian Fault,together with regional gravity, magnetic andpaleomagnetic work. Iceland's program is concerned with 3 areas; (1) the active volcanic zones,

24

(2) the plateau basalt area adjacent to the activevolcanic zones, and (3) general studies of Icelandand the shelf regions. Geological, aeromagnetic,and gravity maps are complete or nearly complete. Heat flow, magnetotelluric, and seismicstudies are underway. Scientists from severalother nations have been working in Iceland incooperation with Icelandic scientists. TheGeodynamics Program has provided considerable stimulus to geophysical and geologicalresearch in Austria focused on the Austrian areaof the Alpine belt. The Finnish program isconcentrated heavily on repeated geodetic andgravity measurements to study crustalmovements in Lapland and the Fennoscandianland uplift, although work is also underway inaeromagnetics, magnetic surveys, paleomagnetism, and seismology.

The Czechoslovakian program concentrates oneight projects; regional studies in the WestCarpathians and the Bohemian Massif, togetherwith more traditional studies of the physicalparameters and structure of the crust and mantlein Czechoslovakia by deep seismic soundingsand heat flow, the physical properties of rocksunder high pressures and temperatures,geochemistry of mobile zones, secular variationof gravity and earth tides, recent crustalmovements, geomagnetism and paleomagnetism.

APPENDIX I

Description of Geodynamics Studies


A. Dynamical Models

Construction of dynamical models of theprocesses in the mantle that can explain platetectonics observations, the thermal history andgravity fields, the origin of the earth's magneticfield, and their possible relation to planetarymotions.


Seismic, gravimetric, geodetic, geomagneticand heat flow measurements as applied tostudies of the structure and dynamics of downgoing slabs, spreading centers, transform faults,and plate interiors. Gravimetric and seismicstudies of heterogeneities in the asthenosphere.Applicable seismic studies of the deep internalstructure of the earth. Calculation of temperaturedistribution by electrical conductivity studiesand seismic mapping of phase transitions.


Ultrasonic and shock measurements on earthmaterials, rheological behavior of earthmaterials at high pressures and temperatures,

equations of state, kinetics of phase transformations, process of magma generation, parti lioning of trace elements under controlledcondi tions of temperature and pressures, thermaland electrical conductivity of rocks at highpressures and temperatures.


Geological, petrological and geochemicalstudies that provide constraints on models of: 1)magmatic differentiation, 2) physiochemicalconditions of deep crustal processes, and 3)mechanisms by which mantle-derived rocksreach the surface. Includes trace element andisotopic studies of upper mantle rocks brought tothe surface as xenoliths in lavas, kimberlitepipes, diapiric emplacements, and through obduction of ophiolite suites. Petrological study ofblueschists and related rocks representative ofsubducted material altered at depth but nowexposed in melanges and other areas that may befossil plate sutures. Investigation of modernvolcanoes as a basis for inferring internaldynamic processes, internal reservoir condi tions, and mass flux and energy balance of thevolcanic process.

II. Boundaries, Movements, and Stru.cture of Lithospheric Plates


Mapping of the horizontal and vertical dimensions of present plates, with special attention tothe subplates in island arc regions. Detailedseismic and geodetic studies of plates presentlybeing broken up. Variations in lithosphericthickness and the properties of the low veloci tyzone, on land and at sea, with particular attentionto high resolution continuous seismic reflectionprofiling.

25


The direction and velocity of present platemovements by geodetic measurements alongactive faults, the direct measurement of verticaldisplacements on land and at sea, the development of satellite geodesy and radio telescopeinterferometry, internal plate deformation,relative direction of plate movement by earthquake focal mechanisms, orientation of sea floorfracture zones.


Paleomagnetic investigations of unsampledplates, mapping of sea floor fracture zones bydepth soundings, time scale of geomagneticreversals, pole positions for the Paleozoic, polepositions for the Precambrian, fine structure ofthe magnetic field, magnetism of sea basalt.

26


Geochemistry and mineralogy of crustalmaterial added to plate margins and intraplateareas; nature of geological structures, especiallyat convergent plate boundaries and attranscurrent sutures within or at plate boundaries; vertical movement of plates as determined by geological means; relation of geologicalstructures to dynamics of plate movement.

APPENDIX II

Details of Federal Agency Activities inGeodynamics Related Programs

Department of Commerce

In the Department of Commerce, studiesrelated to geodynamics are carried out principally in the National Oceanic and AtmosphericAdministration (NOAA) through its NationalOcean Survey (NOS), National Geodetic Survey(NGS), Environmental Research Laboratories(ERL) and Environmental Data Services (EDS).The National Geophysical Data Service of EDSprovides a wide range of information in

seismology, marine geology and geophysics, andgeomagnetism and operates the World DataCenter A for Solid Earth Geophysics. Geophysical information is regularly exchangedbetween this World Data Center and othersimilar centers in the USSR, Europe, and Japan.

Several geodynamics-related projects are alsocarried out at the Bureau of Standards.



The Trans-Atlantic Geotraverse (TAG) is anintensive geological, geophysical andgeochemical investigation of a corridor about 3°(285 kms.) wide across the Central NorthAtlantic Ocean from Cape Hatteras in the UnitedStates to Mauritania in northwest Africa.

The TAG project has four main objectives: thestructure and development of the continentalmargins of eastern North America andnorthwestern Africa, axial processes of the midAtlantic Ridge between 25° and 28° Northlatitude, the structural evolution of the oceanic

crust from the mid-Atlantic Ridge to the continental margins, and the establishment of astandard crustal section within the TAG corridoracross the entire central North Atlantic Ocean.


At the National Bureau of Standards, highpressure studies include the calibration ofpressure scales using the ruby fluorescentmethod, continued work on an ultra highpressure cell, extension of the pressure scale, andsome experimental studies involving behavior ofmaterials at high pressure.

II. Boundaries, Movements, and Structures of Lithospheric Plates


Mineralization processes in the rift valley ofthe mid-Atlantic Ridge and adjacent fracturezones are studied using samples obtained fromthe French-American Mid-Ocean UnderseaStudy (FAMOUS).

B. Present Motion in Plates

The National Geodetic Survey is responsible

27

for the establishment, maintenance, and adjustment of the horizontal and vertical geodeticcontrol networks over the United States. Thesebasic networks are currently being adjusted, thework scheduled for completion in the 1980's. Aspecial Great Lakes leveling program is currentlynearing completion, with its objectives thedetermination of the relationship of the NationalGreat Lakes Datum to Mean Sea Level, incooperation with the Geodetic Survey of Canada.

This survey also passes through the AdirondackMountains where evidence of continued upheaval has been detected. Similarly, a loop to becompleted soon in the Mississippi Valley willprovide data for recent crustal movement in theGreat Lakes area.

Horizontal and vertical networks have beenestablished across the San Andreas Fault atintervals between Los Angeles and San Francisco. These are re-measured as time and fundspermit, though re-measurement would immediately follow any major earthquakes in thearea.

A potentially valuable source of informationfor plate tectonics is obtained by zenith tubemeasurements of polar motion at Gaithersburg,Maryland and Ukiah, California where thesemotions have been observed over the past 75years. Although newer methods of polar motionobservations have shown a potential of higheraccuracy, the question of continuity with pastinformation requires a review of these methods.

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The National Geodetic Survey also maintains agravity base network across the U.S. andplanned reobservations will provide informationon secular gravity changes that are closelyrelated to elevation changes.


A long term program is underway to measuresedimentary processes on the continental marginsediment transport system in the mid-AtlanticBight, and to develop a conceptual model of thissystem. In FY 76 the temporal variability of thesediment substrate will be determined bymeasuring changes in the distribution of itsphysical and chemical characteristics with time.The velocity profile of the boundary layer will bedetermined immediately above the substratesurface to provide a basis for quantifying thetransfer of storm-driven energy from the watercolumn to the sediments.

Air Force

The Air Force supports, through its Air ForceGeophysics Laboratory, a wide range of geodeticand geophysical studies for precise positionlocation, earth size and shape determination,measuremen ts and modeling of the gravi ty field,and geophysical earth motions. Many of thesemission-oriented research programs are closelyrelated to the objectives of the IGP.

Improved knowledge of the earth's propertiesand more accurate models for the gravitationalfield will be obtained by the development ofbetter basic theories, improved instrumentationfor more precise measurements, and the formulation of mathematical techniques for the combina-

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tion of large amounts of heteorogeneous datafrom multiple sources. Basic studies are underway of propagating earth motions andtheoretical investigations to explain the nature oflong-period and aperiodic crustal motions.Theoretical investigations are directed towardpredicting the response of the earth model todynamic and static loading of the crust. In FY 76the North American and European continentalgeoids will be calculated from combinations ofgravimetric and satellite data and the geoid overthe North Atlantic will be obtained from satellitealtimetry data.

Advanced Research Project Agency

The Advanced Research Projects Agency(ARPA) conducts two research programs thatcontribute to the objectives of the IGP. TheSeismic Verification Research Program is concerned primarily with the problem of unidentified seismic events that may arise frompeculiarities in the generation of seismic wavesby certain earthquakes, distortion of seismicwaveforms caused by propagation through

heterogeneous portions of the crust and mantle,or inability to detect seismic waves at highenough signal-to-noise ratio to obtain information diagnostic of the source. The Geodesy andGravity Research Program is concerned withimproved methods for the rapid acquisition ofprecise geodetic and gravity data capable ofproviding improvements in regional gravitymodels.



Special attention is being given to structuralproperties of the crust and upper mantle as well

as lateral inhomogeneities in the mantle underlying the Aleutian Island region, mid-AtlanticRidge, western U.S., Kamchatka and KurileIslands, Tibet, and the Arctic Basin.

II. Boundaries, Movements, and Structure of Lithospheric Plates


Studies involving the determination of seismicsources, the regionalization of sourceparameters, and the characterization of sourceproperties of earthquakes at the plate boundaries, in particular for the case of continent-tocontinent collision, are being conducted to aid inthe mapping of the horizontal and verticaldimensions of present plates.


The anomalous characteristics and cause ofmoderate to large earthquakes (intraplate earth-

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quakes) occurring in a normally aseismic area(Eastern U.S.) are being investigated by integrating all available seismological, geodetic,geomorphological and geologic evidence, andmeasurements of sea level changes. In addition,an integrated field measurement program using avariety of broadband instruments is beingconducted in the seismically active Bear Valleyregion of California (strike-slip fault region) inan effort to more clearly define the spatial andtemporal nature of the source displacementfunction and resultant spectra of signals fromearthquakes in the body wave magnitude range3.5 to 4.5.

Navy

In order to understand its operating environment more effectively, the Navy supportsgeological and geophysical research on thecharacteristics of the seafloor sediments andunderlying rock layers. Laboratory and fieldresearch on the physical properties of mineralsand rocks are also supported to improve surfacebased geophysical techniques for inferring thephysical properties of deep crustal layers. Many

of these mission-oriented programs have a closeconnection with the objectives of the International Geodynamics Project. This research issupported through two programs of the Office ofNaval Research: Marine Geology andGeophysics (MGG-ONR), and Earth Physics(EP-ONR) and through activities of the U.S.Naval Oceanographic Office (NAVOCEANO).


Marine gravity studies are focused upon theproblem of determining the geologic source of theshort (kilometers) and medium (hundreds ofkilometers) wavelength gravity anomalies.These studies include the investigation of thegravitational effects of primary tectonic featuresof the ocean floor, such as ocean ridges, trenches,island chains, seamount chains, fracture zones,and marginal basins (MGG-ONR).

Research on the physical properties of the solidearth are supported on an interdisciplinary basis.These include electrical measurements ofcrustal/upper mantle resistivity-depth distributions; seismic studies of crustal/uppermantle seismic velocity distributions, Q,Poisson's Ratio, seismic velocity transitions and

stress distributions; electrical resistivity ofminerals at elevated pressures and temperatures;effect of microfractures on physical properties ofrocks; and measurements of thermal gradientsand electrical resistivity of crustal rocks to inferinternal crustal heat distribution (EP-ONR).

In part of the Canary Basin, all availableseismic reflection data have been compiled andreduced, and are being analyzed in order todetermine the physiography of the acousticbasement surface. Studies of basaltic rocksdredged along the spreading axis north and southof Iceland are focused on the anomalousgeochemical changes that occur in these basaltsalong the Reykjanes Ridge (NAVOCEANO).

II. Boundaries, Movements, and Strucl:ure of Lithospheric Plates

A number of discreet geological andgeophysical investigations are supported in thenorthwest Pacific. An objective of the program isto examine the dynamics of an old part of thePacific plate. Included in the plate interior are theHawaiian Ridge, Emperor Seamounts, Hess Rise,and the Hokkaido Rise with the Kuril Island Arc,Bonin Island Arc, and Okhotsk Basin at themargins (MGG-ONR).

Better knowledge of the physical, magnetic,and chemical properties of the upper one or twokms. of the crystalline oceanic crust (layer 2)should lead to improved understanding of thedynamics of ocean basin formation. Specific

31

tasks are examining the thickness and velocitystructure, topography, and magnetic properties(MGG-ONR).

Two aspects of marine magnetics are beingexamined. The first is the delineation of theampli tude and configuration of the residualmagnetic anomalies of the world's ocean basinsand their relations to ocean floor structure.Particular emphasis is directed towards thetriple junction anomalies in the South Atlanticand Indian Ocean, the Mesozoic anomalypatterns in the western Pacific, and the regionalfield of the Arctic Basin. The second aspect is animproved definition of the magnetic time scale

through improved analysis and stacking techniques, as well as paleomagnetic studies ofsediment cores (MGG-ONR).

Specific regional studies include examinationof the geologic history, structure, and tectonics ofthe Bay of Bengal and Western Sunda Arc in theIndian Ocean; the structure and interaction of theCocos and surrounding lithospheric plates; andthe structure and seismicity of parts of the Juande Fuca plate (MGG-ONR).

Near-shore magnetic data collected in thenorthwest Pacific Philippines region are underanalysis. A geophysical/acoustic study will bemade on seamounts in the western Pacific, toinclude seismic reflection data, cores and rockdredges, and wide-angle reflection/refractionmeasurements at selected sites. A geophysicalsurvey has been carried out along the GalapagosSpreading Ridge both east and west of theGalapagos Islands (NAVOCEANO).

Recent studies of the mid-Atlantic Ridge usinga near-bottom recording magnometer hasrevealed the fine structure of the earth's magneticpolarity for the first 3.5 million years and similarstudies on other sections are planned. A

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cooperative geophysical investigation of the midAtlantic Ridge south of Iceland with Germanyand Iceland is presently underway. Similarstudies of magnetic data in the vicinity ofCayman Trough will provide data for furtherrefinement of past rates of movements betweenthe Americas. Caribbean geological andgeophysical atlas is presently in progress(NAVOCEANO).

Recent aeromagnetic surveys in the ArcticOcean have now covered about one-third of theEurasia Basin, confirming a separation of theLomonosov Ridge from Eurasia about 60 millionyears ago. Continuation of this aeromagneticsurvey is planned for the next several years(NAVOCEANO).

An extensive acoustic/geophysical/oceanographic survey of the Indian Ocean is planned inFY 76 to include seismic reflection profiles, 3.5kHz high resolution profiles, 12 kHz bathymetry,magnetic and gravity data. Sediment cores andwide angle reflection/refraction measurementswill be taken at selected locations(NAVOCEANO).

Energy Research and Development Administration

The Energy Research and Development Administration (ERDA) consolidates activitiesrelated to research and development on thevarious sources of energy from fossil, nuclear,solar, geothermal, and other energy sources. Aconsiderable amount of this research isgeodynamics-related, carried out primarily in

ERDA's laboratories: The Los Alamos ScientificLaboratory (LASL], the Lawrence BerkeleyLaboratory (LBL], and the Lawrence LivermoreLaboratory (LLL). In addition, ERDA supportsgeodynamics-related research projects through afew university grants or contracts.


A. Dynamic Modeling

At LASL, modeling of geologic processesinclude theoretical, numerical and simulationstudies directed at understanding the emplacement of plutons and the thermal state of theirenvironments, the eruption mechanism ofvolcanoes, computer simulation of the chemistryof hydrothermal alteration, heat flow, and heatand mass transfer in the earth's interior.


In a major program focused on magmaticprocesses at LASL, data are obtained throughfield and laboratory studies of the chemical andphysical state of the earth's upper mantle bystudying rock specimens (xenoliths and hostbasal ts) derived from the mantIe and analogoussynthetic material. This program includes highpressure-temperature experimental geophysics,thermal and electrical conductivities, thermalevolution and convection in the earth's interiorby numerical-theoretical methods, fracturepropagation, laboratory and in situ rockmechanics.

In a planned field experiment by LBL innorthern Nevada, a pattern of drill holes 100-200meters deep will encompass the Battle Mountains regions of high heat flow. Geothermalgradients and thermal conductivity will bedetermined to obtain heat flow. In another LBLproj ect, an attempt will be made to evaluateaeromagnetic data to determine depth to theCurie point. Geothermal activity due to largethermally anomalous masses in the crust, such as

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young plutons, is likely to be associated withshallow Curie-point isotherms.

C. Physical and Chemical Properties and MineralAssemblages

The construction of a physical properties testfacility is planned at LBL in FY 76 to test rocksamples at varying temperatures and pressuresto 400°C and 1,000 bars, respectively. Thermal,electric, and sonic properties of rock-fluid,systems would be measured.

At LASL experimental programs are carriedout in geophysics and rock mechanics using bothexplosive shock waves and static high pressuredevices. These programs are directed at the highp-T properties of silicates, oxides, and metalswith the principal objective the determination ofthe composition of the earth's mantle and core.Research on melting phenomena and solutiongeochemistry currently underway will be expanded to include more rock systems and high PT studies of phase equilibria of individual puremineral phases, mineral assemblages, includingvolatile bearing systems, and the physical andthermochemical properties of silicate melts.Investigations of mineral assemblages in mantlederived xenoliths with electronprobe are inprogress.

The LLL is also involved in a wide range ofexperiments on the static deformation and shockproperties of minerals and rocks to permitaccurate predictions of the response of the earth'scrust to various types of stress and loading. Aresearch program is in progress to improveunderstanding of the response of geological

media to mechanical stimuli such as explosionsor in situ stress. Rock behavior on a microscopic(grain size) scale will be modeled, and resultsverified by experimental work on wellcharacterized ceramic synthetic rocks. With thehelp of statistical theory, modeling will then beextended to the larger scale of joints, faults, andother inhomogeneities that exist in the field. Alsoat LLL numerical modeling of both small scaleand field experiments will be conducted for preexperiment design and post-experimentanalysis. In an iterative manner, these shouldprovide a basis for advancing understanding andimproving predictive capability.


Field studies at LASL related to volcanism orplutonic processes provide data in the form ofstructural relationships, detailed studies ofpetrochemistry of lavas and xenoliths, and alsofrom physical observations such as spectroscopyof volcanic gases. These activities include fieldstudies of igneous terranes directed at theunderstanding of such igneous processes as theemplacement of magmas from depth, thedynamics of thermal problems associated withpluton emplacement and volcanic eruptions, andtheir relationship to tectonic features such asplate interactions. Included are field studies ofthe Rio Grande rift and its associated volcanicsboth basalt and caldera complexes, andesite

volcanoes of the Cascades of northern California,and field studies of active volcanoes. Methodsinclude movies, high-speed and time-lapsephotography, spectroscopy and interferometryfor gas and light isotope analysis, geodesy byoptical and laser methods, seismology, aerialphotography and remote sensing, air, gas andparticulate sampling at low and very highaltitude by aircraft, shallow boreholegeophysics, and petrological studies of lava,volcanic rocks and xenoliths from kimberlitepipes and andesites.

Laboratory studies at LASL on rock andmineral samples provide major, trace elements,and isotopic data obtained with the goal ofestablishing the temperature, pressure, and timeof formation of the material. From this information, combined with careful field mapping, asample can be placed in its historical context andits physical or chemical history established.

At LBL the distribution of trace, major, andradiogenic-heat-producing elements in Mesozoicinstrusive rocks, and Tertiary and Quaternaryigneous rocks, on east-west traverses across theGreat Basin will be examined. Radiogenic heatproduction will be determined, and interelementratios compared which may indicate the presenceof, and depth to, plates of oceanic crust thatfoundered beneath over-riding continentalplates.


Under a cooperative arrangement between twouniversities, seismic data are analyzed from anetwork of short period telemetered seismicstations in the Shumagin Islands near the tip ofthe Alaskan Peninsula, and from a large apertureseismic array in the eastern Aleutian arc east ofUnalaska Island. This is part of a seismic tectonicstudy of the active Pacific-North American plateboundary in the eastern Aleutian arc.

At LASL the present state of activity of boththe Rio Grande rift zone and the Jemez caldera aremoni tored by geophysical observations and aregional seismic network to provide data on amaj or continental rift feature and the unusualvolcanism associated with maj or rift zone

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processes. The Rio Grande rift is relatively youngand may be a maj or rift zone inan incipient stageof formation.

Possible topical studies would include: borehole geophysics and core studies along the RioGrande rift using LASL's 300-m drill rig, the corestudies to include petrological, geochemical, andphysical properties; regional seismicity usingLASL's seismic net; regional geodesy using threecolor laser geodimeters, tilt and long baselineprecision leveling; and deep seismic reflectionprofiling (University consortium).

At LBL a study is underway to detect changesin electrical resistivity that might be caused bytectonics within the San Andreas Fault system.

National Aeronautics and Space Administration

The NASA Earth and Ocean PhysicsApplications Program, through satellite andlunar observation techniques, contributes to themajor rGP elements concerned with geophysicalobservations of internal processes, and presentmotions of lithospheric plates and the earth'spole. The NASA projects involved are theTectonic Plate Motion, Measurements Systemsand Forecasting Techniques, Experimental DataAnalysis, the Lunar Ranging Experiment (LURE)and the Three Satellite Systems, the GeodynamicExperimental Ocean Satellite (GEOS-C), theLaser Geodynamic Satellite (LAGEOS) and theOcean Dynamics Satellite (SEASAT-A).

The objective of the Tectonic Plate Motionproject is to utilize existing capabilities tomeasure precise motions between defined points,using both laser tracking and very long baselineinterferometry.

Measurements Systems and ForecastingTechniques activities involve the planning andimplementation of scientific and technicalresearch and other supporting activities inuniversities, nonprofit and industrial organizations, NASA centers, and other Governmentagencies.

Experiment Data Analysis provides for theanalysis and synthesis of data obtained inEOPAP investigations, e.g. the processing,evaluation, and analysis of data taken duringGEOS-3, Skylab, Apollo-Soyuz Test Project, etc.

The Lunar Ranging Experiment will utilizeexisting knowledge of lunar motions and continuing range measurements to the lunarretroreflectors to support investigations on earth

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rotation, polar motion and plate motions. Therange measurements will be acquired at fixedstations located at the University of TexasMcDonald Observatory and the University ofHawaii Maui Laser Ranging Observatory.

The Geodynamic Experimental Ocean Satellite(GEOS-3) presently orbiting project has theobjective of demonstrating a much improvedaltimeter that cannot only measure thetopography of the earth's oceans to an accuracyof approximately 30 cm, but that can alsomeasure the wave height (or sea state). Themeasurements of the ocean topography willprovide the capability to make a more precisemathematical description of the earth's gravityfield and improve the measurements of thevariations in solid earth geometry and othergeophysical areas.

The Laser Geodynamic Satellite (LAGEOS)project, launched in 1976, with its very densespherical satellite covered with laser reflectors,has the objective of providing the capability tomake very accurate measurements of the earth'scrustal motions (tectonic plate movement, faultmotions, polar wobble and rotation rate).

The first Ocean Dynamics Satellite (SEASATA) due for launching in 1977 has as its objectivethe demonstration on a global scale of anintegrated monitoring and data gatheringcapability for a wide range of physical oceancharacteristics, including wave height, shape,and direction, the location and motion ofcurrents, global circulation patterns, oceansurface, wind speed and direction and the oceangeoid (topography of the oceans).

National Science Foundation

The National Science Foundation (NSF),forbidden by its charter to conduct research oroperate research laboratories, supports scientificresearch and programs to strengthen scientificresearch potential through grants and contracts.Most of the thousands of awards made annuallyare to nonprofi t organizations-principally U.S.universities and colleges. Traditionally, NSF hassupported basic research through unsolicitedproposals by individuals, although in recentyears-there have been an increasing number ofrequests for major projects involving a greatmany scientists, often from consortia of universities.

The grants or contracts made that aregeodynamics-related fall in both the large andsmall categories. The Ocean Sediment CoringProgram is an example of a project involving amaj or facility, the Glomar Challenger drillingvessel. However, most of NSF funds, and nearlyall of the awards, are for small projects of one ortwo scientists.

In FY 74, NSF awarded 243 grants or contractsthat were geodynamics-related to 78 universitiesand other nonprofit organizations. The ten majororganizations that contributed most togeodynamics through NSF support were Columbia University, the University of California atSan Diego (including Scripps Institution ofOceanography), Battelle N.W., Woods HoleOceanographic Institution, University ofHawaii, MIT, University of Washington, Harvard University, California Institute ofTechnology, and Stanford University. Althoughthis list may change each year since grants are foronly 1 or 2 years, most of the universities notedabove will be among the leading contenders. In

FY 75 Cornell University received a large awardfor their deep seismic sounding efforts, whilework by Battelle for geodynamics information atMaryville, Montana decreased. On the whole, itis the universities with major facilities thatfigure most prominently in geodynamic investigations. Since there is a constant change inproposals received, it is impossible to predict anexact future categorization, even though totalbudget figures are available. Informationsupplied in this report indicates what is expectedin FY 76, although FY 74 figures are the latestthat have been documented.

The NSF supports geodynamics-related projects in several offices, as follows: the EarthScience Project Support in the Division of EarthSciences: Geophysics, Geochemistry, andGeology; the Ocean Sediment Coring Program inthe Division of Earth Sciences; the SubmarineGeology and Geophysics Program (SG&G) in theOceanography Section of the Division ofOceanography; the Seabed Assessment Programin the International Decade of Ocean Explorationof the Division of Oceanography; the Polar EarthSciences Program in the Office of PolarPrograms; and the Advanced Geothermal EnergyResearch and Technology Program (AGERT) inthe Division of Advanced Energy Research andTechnology. Other offices that also provide someof the facilities and logistics for the researchprojects are the Office of OceanographicFacilities and Support of the Division ofOceanography, for oceanographic research shipsupport, and the Earthquake EngineeringProgram of the Division of Advanced Environmental Research and Technology for the nationals trang-motion seismic network.


A. Dynamic Models

Within the Geophysics Program, about half adozen grants are normally made per year formodeling studies of the dynamics of the earth'score, geodynamo, and on convective motion in theearth's mantle and at the crust-mantle boundary.

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A major effort by about 50 individual grants isbeing made by university scientists to studyinternal processes by geophysical methods.These efforts come from various offices

throughout the National Science Foundation thatdeal wi th geodynamics-related programs, but aremost heavily concentrated in Geophysics, SG&G,and in AGERT. The principal tool for thegeophysics studies is earthquake seismology,and in most of these studies, heavy reliance is puton the records of the World Wide StandardizedSeismograph Network, with about 20 grants andnearly $.90M total. Geothermal studies arecarried out mostly in AGERT in the search formethods of locating sources of energy within theearth. Seismic studies of internal characteristicsby the use of controlled explosives or mechanicalsources account for nearly $.50M in about 10separate university grants. A few universitiesare experimenting with the Ocean BottomSeismograph (OBS) in an effort to obtain moredetailed information on the ocean sediments, aswell as a new input to earthquake monitoring. Amajor award in this category, which is nowdeveloping, is concerned wi th the fine structureof the crust and upper mantle in which continuous seismic reflection techniques used inpetroleum exploration seismology can be extended to deeper structures in the earth. If seismicdiscontinuities can be mapped in the lower crustand upper mantle, a great deal of information canbe obtained on the evolution of the continentalcrust from the primitive mantle and on very deepseated control of surface features. Research ontelluric, magnetotelluric, electromagnetic induction, and electrical resistivity methods areincreasing and in FY 1974 about $200,000 wasspent on such projects. A few gravity studies aresponsored through the Geophysics Program oncontinental work and gravity measurements atsea were carried out routinely on a few of theoceanographic vessels. Most of the studies aboveare concerned with the continental U.S. andHawaii, but several studies were carried out inMexico, Iceland, and in Southeast Asia.


These studies by the NSF can be divided intotwo or three general groups adding up to about 40awards totalling almost $2 million. The supportby the Geophysics Program is heavily orientedtowards the investigation of sonic velocity, flowmeasurements, development of microcracks,

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shear strength and electric properties of rocks,particularly the ultrabasic rocks most likely tohave originated in the lower crust and uppermantle under high pressure and hightemperature. Considerable development work inthe pas t few years has gone into methods ofobtaining high temperatures and high pressures.These include ultrasonics and shock compression, as well as s taUc compression, and theadvancement has been made at relatively few ofthe major universities. In the GeochemistryProgram, in many cases using high-temperature,high-pressure equipment, 15 to 20 studiesinvolving about $.90M are concerned with a largevariety of geochemical problems such asequilibrium and mass transfer among mineralsand aqueous solutions, the diffusion kinetics oftrace elements, mineral crystal chemistry, thermodynamics of ionic interactions, rate andmechanism of exsolution in minerals, and themeasurements of ion-pair formation constants.The mOE office funded a few projects in whichsamples recovered from the mid-Atlantic Ridgewere analyzed.


This area of geodynamics-related programs iswell represented in NSF with nearly 60 awardstotalling between 2.5 and 3.0 million dollarsannually. Most of these awards are made inGeochemistry, Geology, Submarine Geology andGeophysics Programs. The GeochemistryProgram supports nearly 40 awards varyingwidely in the topics studied with 6 to 10 on thegeology, geochemistry and geochronology ofvolcanic rocks from several geographic areas,though principally the United States and Mexico.Several mantle or deep crustal rocks that areexposed at the surface in various areas of theworld are also studied in these programs. TheSG&G Program supports many studies of thebasalts obtained from the Ocean SedimentCoring Program, and mOE supports studies ofrocks recovered from submersibles in theFAMOUS Experiment on the Mid-AtlanticRidge. A few studies of the geochemistry andpetrogenesis and geochronology of rocks obtained from the Dry Valley Drilling Proj ect aremade under the Office of Polar Programs.

II. Boundaries, Movement, and Structure of the Lithospheric Plates


The NSF effort in this category, which is about$2 million per year, is largely in the oceanic areasin the SG&G and mOE Programs. A number ofgeophysical studies have been made of theboundaries and structure of the Nazca Plate, theeastern and southeastern parts of the AsianPlate, and the western part of the Pacific Plate.The Sunda Arc and the Mid-Atlantic Ridge arealso under investigation. Use is made in some ofthese studies of the relatively new multi-channelmarine seismic units, often with high energy airguns, as well as sonabuoys and ocean bottomseismographs. In addition to the seismic work,support has also been provided for majorprograms involving gravity, heat flow, andmagnetic measurements in the continentalmargin of west Africa and eastern SouthAmerican in order to construct the various stagesof the opening of the South Atlantic.. TheGeochemistry Program includes isotopic studiesof the older geologic history of the southwesternmargin of North America and the tectonicevolution of the South Kenya rift zone.


A program with about one-half dozen awardsin the Geophysics Program involves the modeling of the response of the earth to late quarternary ice melting, earth tide studies, andapplications of atomic clock interferometry. Amaj or program has been initiated on thegeophysical application of very long baselineinterferometry. This technique has the potentialto clarify our concepts of the current nature ofplate motion and deformation.

C. Plate Boundaries and Rates of MovementsDuring the Past

In this category the NSF supports about 40investigations with an estimated total of $2.3million which includes a sizable portion ($.90M)for the Ocean Sediment Coring Program ofScripps Institution of Oceanography, plusseveral research studies of cores of OSCPproj ects that are not part of initial cruise reports.This research on core material is carried out by

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scientists from many universities and requestsare expected to continue to grow. The NSFsupport of research on these cores, mainly inSubmarine Geology and Geophysics, is actuallya fairly small percent, about 10-20, of the work onthe cores for this program. Other investigatorsalso obtain samples for studies and, although afew of these may be reported to this Committeeby other agencies, many samples go to investigators from industry and from universities,both domestic and foreign, where support is notrequired from the Federal Government. TheOcean Sediment Coring Program is changingsomewhat in objectives, as it begins its IPODphase in late 1975, with concentration on deepcrustal drilling and reduced emphasis onpaleoenvironmental and ocean margin drilling.Thus, this program will be contributing agreaterpart of its effort to geodynamics-related projects.

Other investigations in this category aresupported through Geophysics, SG&G, and theOffice of Polar Programs, and these are aboutequally divided between paleomagnetic proj ectsdealing with past plate movements andgeological and geophysical studies in areas ofplate boundaries. The Antarctic Program involves sediments taken from the Eltanin andfrom the Dry Valley Drilling Proj ect, as well asgeological studies in the Antarctic Mountainsand the Antarctic Peninsula. The Eltanin, nowoperated by the Argentine Government andrenamed the Islas Orcadas, works in the SouthAtlantic Ocean in a cooperative study byArgentine and U.S. scientists.

D. Plate Accretion, Composition, and Structure

The NSF support in this category is about $1.5million in 20 or more grants and contracts, withefforts of the Ocean Sediment Coring Programestimated at about $.30M. A large contributioncomes from the International Decade of OceanExploration in their proj ects to provide maj orsupport to Woods Hole Oceanographic Institution for the studies of the East Atlantic Continental Margin and to the Lamont-Doherty GeologicalObservatory of Columbia University for thestudy of the continental margins of Argentinaand Brazil.

U.S. Geological Survey


A. Dynamical Models

Studies of dynamical models are carried out aspart of the Geological Survey's EarthquakeHazards Reduction Program, GeothermalProgram, and Geophysical Surveys Program.Recent studies by Survey scientists suggest thereliable prediction of damaging earthquakes maybe feasible within a few years for someearthquake-prone areas. Field measurementscoupled with laboratory experiments andtheoretical studies of precursor phenomena arebeing carried out by Survey scientists in order toestablish a firm physical basis for predicting thetime, place and magnitude of earthquakes. Thisresearch effort includes the collection and theanalysis of data on strain accumulation andrelease, and the study of the behavior of rocksunder physical conditions similar to thoseencountered in the crust and upper mantle.

Computer modeling of fault displacements isunderway to achieve an understanding of faultmechanisms and related effects. These numericalmodels are used by Survey scientists to developsimulations of vertical and horizontal deformation arising from possible dilatant changes in afault zone. Both plane-strain and threedimensional analyses have been applied toproblems of source mechanics, earthquakeprediction, and earthquake modification.

Survey scientists also study the mechanismsby which water and heat are transferred ingeothermal systems within the crust. Conceptualmodels of selected well-known geothermalsystems-based on their known geologic,hydrologic, geochemical and geophysicalsettings-are being improved by means ofshallow drilling to obtain corroborative thermohydrologic data.

Information about the distribution ofmagnetization and electrical conductivity withinthe earth is gained by orbiting satellitemagnetometers which record broad-wavelengthmagnetic anomalies plus the small-amplitudefluctuations in the earth's magnetic field

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[micropulsations) by instruments at land-basedgeomagnetic observatories.


Numerous geophysical methods are being usedby scientists of the U.S. Geological Survey todetect subsurface structures and to describe thedynamics associated with the margins andinterior of the North American plate. Thesemethods include microearthquake, refractionand reflection seismic, heat flow, magnetic,gravity, electrical resistivity, electromagnetic,and thermal radiometric studies of the continent,continental shelf, and continental slope.

Microearthquake studies based on densearrays of short-period seismographs (microseismic nets) permit three-dimensional mappingof active fault zones as well as identification of"locked" sections of known active faults. Recorded microearthquakes are correlated withmeasured strain patterns in studies of thepropagation of strain or slip events throughoutthe network. Microseismic networks are currently operating in California, Washington, Nevada,Wyoming, Utah, New Mexico, Missouri, Alaska,and Hawaii.

In support of the microseismic studies, refraction seismic surveys are made over broad regionsto determine the physical properties, elasticregime, and principal structure elements of thecrust and upper mantle.

Heat flow measurements also contribute to anunderstanding of processes occurring within theearth. Measurements of geothermal gradients indeep wells and mines together with laboratorymeasurements of thermal conductivity of rocksand radioactive heat production provide information about the thermal regime of the earth'scrust and upper mantle.

Surface manifestations of heat flow aredetected by analysis of thermal infrared imagesobtained over broad regions. After deleting solarheating effects from crustal heating effects, the

image information is analyzed using thermalinertia and spectral reflectance data obtained inthe field. The thermal and reflectance data maybe used as indirect measurements of high surfaceheat flows associated with hydrothermal activity in the crust.

In addition to seismic and heat flow studies,magnetic and gravity surveys are made toidentify zones of anomalous magnetization anddensity in the crust and upper mantle. Magneticsurveys made by air, land vehicle, or on foot areextremely useful in delineating accumulations ofserpentine within strands of the San Andreasand related faults; ophiolitic rocks representingancient oceanic crust, which occur in the California Coast Ranges and Sierra Nevada foothills;and subsurface shapes of plutonic rock massifssuch as the Sierra Nevada and Boulder batholithsof western United States;

Magnetic surveying over broad areas is accompanied wherever feasible by regional gravitysurveying. The gravity data have proven to beespecially useful in major sedimentary basins,low-density plutonic rocks that have beenintruded into metamorphic rock complexes, highdensity mafic and ultramafic rocks representingcrustal and upper mantle sources, and highdensity relatively nonmagnetic terranes ofmetamorphic rocks.

Various electrical and electromagnetic techniques such as nc. resistivity, transient electromagnetic, audio-magnetotelluric, inducedpolarization, electromagnetic, self-potential, andtelluric-current methods are used for detectingzones of anomalous electrical conductivity in thesubsurface. These anomalous zones may reflectstratigraphic or structural barriers controllingthe distribution of saline ground water or regionsof elevated temperature associated with highgeothermal potential.

Continental geophysical investigations mergewith marine geophysical research at the Atlanticcontinental margin where marine seismic reflection, seismic refraction, magnetic, and gravitysurveys are made to investigate the deep structure of the continental shelf and slope. Currentinvestigations involve structural interpretationsand evaluations of the thickness and distributionof sedimentary rocks in the Baltimore CanyonTrough and Georges Bank basins.


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Because the physical properties and chemicalcompositions of most rocks and rock-formingmagmatic materials cannot be directly measuredin their crustal and mantle environments, theseproperties must be analyzed in the laboratorywhere physical and chemical conditions can besimulated. Information about the composition,state, temperature, and stress conditions in theearth's interior is obtained in an integratedprogram of laboratory and field studies inmineralogy, igenous petrology, metamorphicphase petrology, phase equilibria, thermodynamics, isotopic geochemistry, radioelement analysis, neutron activation, and rockmechanics. This program is supported by comprehensive compilations of geochemical andthermodynamic data accessed by digital computer.

Mineralogic research is concerned mainly withprecise measurements of the physical propertiesof rock-forming minerals aimed at determininghow the thermal and stress histories of mineralsaffect their compositions and properties.

Research in igneous petrology is directedtoward understanding magmatic systems, withspecial emphasis on studying the relation ofchemical variations to physical properties and tosuch rate-dependent properties as viscosity,diffusion, and kinetics.

Phase equilibria studies of multicomponentsystems, which are fundamental to currentresearch in igneous and metamorphic petrology,are applied to crystal chemistry and physicalchemistry data of rock-forming minerals.

Contributing to information obtained by phasepetrology and thermodynamic studies is a broadarea of research in isotopic geochemistry. Thisresearch includes investigations of light stableisotopes, such as carbon, hydrogen, oxygen, andsulfur, and radiogenic isotopes, such as strontium, lead, and intermediate daughter productsin the uranium and thorium decay series.

An essential companion to the various studiesof the chemical composition of rocks andminerals are investigations of the physicalproperties of these materials in laboratoryexperiments that duplicate conditions in theearth's crust and upper mantle. This research inrock mechanics is largely conducted with experimental equipment that simulates conditionsat depths of up to 30 kilometers. Mechanical,elastic, and thermal properties of rock samplesare currently measured at pressures of up to 10

kilobars (approximately 10,000 atmospheres)and temperatures of up to 1,000ae.


Geologic constrains on models of plate tectonicevolution and processes are being investigated ina wide variety of geologic settings.

In Washington, Oregon, and California,petrologic and structural studies of volcanic,sedimentary, and plutonic rocks supported bydetailed geologic mapping and regional synthesisof large areas of the Cascade, Olympic, andKlamath Mountains are helping unravel thetectonic history of the western margin of theNorth American Plate and to clarify its interaction with the Nazca and Pacific plates duringMesozoic and Tertiary time.

Both detailed and reconnaissance studies ofvolcanic rocks and associated plutons of Tertiaryage in the San Juan and Absaroka Mountains andin central Idaho are underway to help explain therelation between the chemistry of the igneousrocks erupted through the North American plateand geodynamic processes along the westerncompressional margin of the plate.

Studies in geochemistry and geophysics areproviding cons train ts to models of properties andprocesses of plate tectonics through investigations of igneous and metamorphic rocksand of active and dormant volcanoes. Detailedstudies of ankaramites in Hawaii, calderadeposits in New Mexico, and basalts in thePacific Northwest are being made to estimatedepths of phenocryst formation and development, physio-chemical processes and crystallization history in large volumes of silicic melt, andthe mechanics of extrusion and spreading ofprodigious volumes of basalt over vast areas.

Additional studies of the generation andmovement of magma are being conducted at theHawaiian Volcano Observatory, wheremeasurements of deformation at Kilauea Volcanoare made and examinations are conducted of oldlava flows and of magma in the process oferuption.

All of these investigations of igneous rocks are

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supplemented by field and laboratory studies ofmetamorphic rocks that are providing information on load, strain, and fluid pressures duringmetamorphism as well as means of inferringdepths of partial melting.

Consideration of the theory of plate tectonics isan important element of Geological Surveyresearch on mineral resources, because models ofore genesis that explain the relationship of oreforming processes to other geologic eventsshould improve the capability to predict thepresence of useful deposits. The emphasis ofpresent studies in geodynamics as applied to oredeposits is aimed at understanding the origin ofimportant regional structural features and thecorrelation of the geologic environments ofdeposits with identifiable parts of the platetectonic cycle.

Mapping and petrologic studies are showingthe existence of island arc volcanic rocks and ofophiolite complexes indicative of subduction andpossibly obduction along the margin of the NorthAmerican plate in late Paleozoic and earlyMesozoic time.

Reconnaissance studies in southwest Oregonare aimed at determining how podiformchromite-bearing ultramafic and mafic bodiesand related melange units of volcanic rocks fromisland arcs were scraped off the oceanic plate andjuxtaposed on the North American plate inMesozoic time.

Studies of the base-metal deposits in theEastern States are concerned with examiningevidence that links mineralizing episodes to platedeformation before and during opening of theproto-Atlantic in early Paleozoic time. Some ofthese deposits provide clues that pulses ofmineralization occurred in paleoaquifers whoseflow regimes may have been determined bywarping during early stages of rifting.

In Puerto Rico, geologic mapping, isotopicdating, and petrologic studies are attempting toestablish the relations between the emplacementof porphyry copper deposits, volcanic andplutonic rocks, and the subduction events ofCretaceous to Eocene age.



The Worldwide Network of StandardSeismographs (known as WWNSS), composed of31 continuously recording stations in the UnitedStates and 85 similarly instrumented cooperativestations in 68 other countries is the mostimportant international seismological effort.This network is the essential source for theseismological data that are used in locatingearthquakes, determining focal mechanisms,investigating seismic wave propagation, anddeveloping concepts of global and regionaltectonics. The Geological Survey operates 7seismic observatories in the conterminous United States, Alaska, and Guam and providesequipment maintenance and supplies for theother stations of the WWNSS.

The Geological Survey's National EarthquakeInformation Service (NElS) in Golden, Colorado,is responsible for receiving data on potentiallydamaging earthquakes, rapidly locating suchearthquakes, and notifying the properauthorities and the public. NElS locates as manyearthquakes worldwide as can be accurately andrapidly determined with data collected fromUSGS observatories and seismic stations andfrom the WWNSS.

USGS scientists are continuing research intothe geologic nature of the mid-ocean plateboundaries. A cooperative investigation, theFrench American Mid-Ocean Underseas Study(FAMOUS), provided a unique opportunity fordirect observation of the topography and geologyofthe Mid-Atlantic Ridge in the region southwestof the Azores Islands. Using deep submersiblecraft, Geological Survey geologists were able toobserve, photograph, and sample across theinnermost rift valley of the Ridge.


Precise geodetic techniques-geodimeter surveys for horizontal movements and level surveysfor vertical movements-are used to determineelastic strain accumulation and strike-slip alongfaults and to detect premonitory strains thatmight be useful for earthquake prediction.Trilateration networks, which are resurveyed

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annually, are stitched across faults of the SanAndreas system, the Nevada seismic zone, theWasatch fault in Utah, and in the Hebgen Lakearea of Montana.

Sea level measurements recorded at automatictide gages also are being studied for theirpossible utility in determining crustal uplift orsubsidence along tectonically active coast lines.National Ocean Survey tide gage records alongthe coast of the western United States andAlaska are being analyzed to detect possibletectonically induced trends.

Seismomagnetic effects along western UnitedStates fault zones are being investigated as anindirect means of monitoring crustal stress. Oneaspect of the program has been to search forbroad-scale long-period effects with a pair ofmagnetometers that operate synchronously in a"leap-frog" survey mode.


Curren t paleomagnetic research includes refining the geomagnetic reversal time usingradiometrically dated volcanic and plutonicrocks as well as stratigraphically dated sedimentary rocks from the Western and SouthwesternUnited States.

Other major paleomagnetic problems related tointerpretations of sea floor spreading rates andapparent polar wandering are the decrease inamplitude of magnetic anomaly stripes withincreasing distance away from a spreading axisand fluctuations of the geomagnetic field intensity throughout geologic time. Paleomagnetic andpetrologic data from samples of sea floor and seamount basalt from the Hawaiian-Emperorvolcanic chain indicate that the observeddecrease in anomaly amplitude away from aspreading center is caused by oxidation oftitanomagnetite to cation-deficienttitanomaghemite within the basalt.

Recent research in geochronology, important toimproving the time framework for interpretingrates of plate motion and tectonic processes,includes investigations of the 4°Ar/39 Ar agespectrum dating technique. This total fusion

technique, which can be used on the samematerials and nearly the same age range as theconventional technique, has the advantage ofusing smaller and less homogeneous samplesthan those used with the conventional technique.

Other research in geochronology is concentra ted on the use of thermal uminescence (TL) as adating tool for very young volcanic rocks. Theage range over which the TL method isdemonstrated to work using samples independently dated by C14 and K-Ar methods is2,500 to 450,000 years for tholeiitic basalts and4,500 to 200,000 years for alkalic basalts.

D. Plate Accretion, Composition,and Structure

Much of the Geological Survey's research onthe Pacific margin of the Americas Plate isconcentrated on the San Andreas Fault zone fromthe Salton Trough to the Mendocino Fracturezone. Significant efforts are also underway in thevicinity of the Gorda rise and Juan de Fuca Riseand along the Aleutian Trench-Arc system andcoastal Alaska. A major objective of this researchis locating recently active fault strands withinthe San Andreas system and the determination ofthe tectonic history along this active platemargin.

A detailed analysis of the intense folding andfaulting in the Salton Trough is underway todetermine the tectonic history of the area. Thesestudies should establish or refute the hypothesisof transform faulting and sea-floor spreading inthe Salton Trough. From the Salton Troughnorthward to the Mendocino Fracture zone, theSurvey is engaged in detailed mapping of PreTertiary to Recent deposits to determine thelocation, direction, and magnitude of displacements and the recurrence interval offaulting along the San Andreas, Garlock,Hayward, Concord, Calaveras, Sierra Nevada,Elsinore, and San Jacinto faults.

Geologic and geophysical studies of the Oregonand Washington continental margin are designedto unravel the tectonic history of this part of thePacific margin and to relate the deformationalhistory to mineral resource accumulation andigneous activity. The unique onshore exposuresof oceanic crust provide an excellent opportunityto infer offshore plate boundary geology.

Detailed mapping of active surface faults and

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the evaluation of geologic evidence for LateCenozoic faulting is in progress along coastalAlaska. In western Alaska the emphasis is ondeciphering the Tertiary and Quaternarygeology and biostratigraphy of the coastalregion, the continental shelf, and the offshoreislands. The objective of this study is to determine and correlate the nature and rates of pastand on-going crustal deformation. Thestratigraphy and tectonic style of the shelf andslope of the Beaufort-Chukchi sea area are beingstudied by relating the onshore geology in theBrooks Range thrust belt to the offshore areas,using seismic reflection, magnetic, and gravityprofiling. Seabed sampling and heat flow studiesare also contributing to a synthesis of theregional tectonic picture.

Since the early 1950's the Geological Surveyand other Federal, State, and private institutionshave assembled a prodigious amount of geologicinformation on the Colorado Plateau. Theoriginal work, primarily large-scale geologicmapping in support of uranium exploration, isnow being synthesized and compiled at 1:250,000scale for the entire Colorado Plateau. Thissyn thesis of vast amounts of stratigraphic andstructural information should provide an integrated data base to help answer the perplexingquestions of why and how this plate fragmentrose epeirogenic ally and escaped the intenseLaramide and Post-Laramide deformations thataffected the Basin and Range Provipce to the westand the Rocky Mountains to the east.

The geologic features of the sedimentarywedge under the Atlantic margin of the AmericasPlate are being determined by shallow (300meters or less} core drilling. Studies of thepaleontology, lithology, mineralogy, andgeochemistry of the cores provide a regionalpicture of the depositional history of the area.This study will provide information about therelationship between crustal tectonic fluctuations and transgressions and regressions ofthe sea, and provides control for marinegeophysical investigations. Geophysical interpretations of the offshore sedimentary sectionand basement complex are based on seismicreflection and refraction surveys, plus gravityand magnetics data. From these data the geologyof the shelf, slope, and rise are studied to identifythe structural and tectonic features.

first annual report of adhoccommittee ongeodynamics to … · 2010. 5. 3. · shattered. to...

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