UNITED STATES DEPARTMENT OF THE INTERIOR GEOLOGICAL SURVEY

REGIONAL BEDROCK GEOLOGIC MAPS ALONG THE DALTON HIGHWAY,

YUKON CROSSING TO TOOLIK, ALASKA

Compiled by

W. P. ~ r o s & and W. W. Patton, Jr.

Open-F i 1 e Report 82-1071

This report i s preliminary and has not been reviewed for con- formity w i t h U.S. Geological

Survey editor i a1 standards and stratigraphic nomenclature.

TABLE OF CONTENTS

Page

Introduction ----------------c-q-----1------------------------------ 1

Correlation of map uni ts , Map A .................................... 3

Geologic symbols, Maps A and ..................................... 3

Map symbols, Maps A and & .......................................... 3

Description af map u n i t s , Map A .................................... 4

Sources of map infomation, Map A ................................. 5

Correlation of map units, Map B .................................... 6

Description of map units, Map B 7

Sources of map information, Map B .................................. 9

ILLUSTRATIONS

Figure 1, Index map ............................................... 2

Map A . Yukon Crossing t o Wiseman .............................. Plate 1

Map B. Wiseman t o Tool jk ....................................... P l a t e 1

INTRODUCTION

The Dalton Highway was originally buff t as a haul road f o r construction o f the trans-Alaska p i p e l i n e , and has now been opened t o the public from L i vengood t o the southern Brooks Range. Reconnaissance geological quadrangle maps at 1:250,000 scale show the bedrock geology o f the region crossed by the highway between Livengood and the Nor th Slope; several o f these maps were published before the highway was b u i l t . In preparation for a highway f i e ld t r i p t o be sponsored by the Fourth International Conference on Permafrost in Fairbanks in 1983, we have s m a r i z e d the geology frm these maps f o r a 50-km wide strip along the highway from the Yukon River to the northern foothills of t he Brooks Range.

The strip map, a t 1:500,000 scale, i s i n two parts (Fig, 1 ) . Map A covers the region from the Yukon crossing t o the town of Wiseman i n the southern Brooks Range. Map 8 covers the region from Wiseman to the northern f o o t h i 11s af the Brooks Range near the abandoned Tool i k construct ion camp. These maps emphasize the regional differences i n character o f the various bedrock terranes crossed by the highway; t he re f ore, some geologic u n i t s r hown on the original maps have been grouped and generalized. An even broader regional overview i s given briefly i n the report by Patton and others (1977) l isted i n the references for Map A. The traveler interested in the details o f the roadside geology will need t o consult the original geologic quadrangle maps listed as sources o f map information as well as the new edit ions o f the topographic quadrangles t h a t show the 1 ocati on o f the highway.

-- 1 Figure 1 . Index map o f Alaska I

showing l oca t i on of map

areas A and 0 . I

CORRELATION OF MAP UNITS

Map A Yukon Crossing t o Wiseman

I Metamorphic I Igneous Sedimentary rocks rocks rocks

I Miocene

1 Pa 1 eocene

Upper Cretaceous

Lower Cretaceous

1 QUATERNARY d .

t

TERTIARY

CRETACEOUS

JURASSIC

TRIASSIC

PERMIAN

PENNSYLVANIAN

NISSISSIPPIAN

DEVON I A M

GEOLOGIC SYMBOLS Maps A and R

Contact. Incl udes some faults --- Faul t . Dashed where approximately

1 ocaled. - / = , . . .

Thrust f a u l t . Saw teeth on upper pla te . Dotted where concea 1 ed.

MAP SYMBOLS Maps A and B

Locat ion and name o f town o r cons t ruc t i on camp.

5 Locat ion and number o f pump s t a t i on.

3

DESCRIPTION OF MAP UNITS

Map A, Yukon crossing t o Wiseman

Sedimentary Rocks

UNDIFFERENTIATED SURF I C I A L DEPOSITS (Quaternary) --Shown only in the 1 argest val I eys.

SEDIMENTARY ROCKS (Miocene?) --Tuff, s i 1 tstone, conglomerate and coal. flonmari ne.

CONGLOMERATE AND SANDSTONE (Upper and Lower Cretaceous)--Clasts o f quartz, quartz i te , schist and Igneous rocks. Nomar i ne.

IGNEOUS PEBBLE CONGLOMERATE (Lower Cretaceous; A 1 b i an)--Cl asts of mafic volcanic rocks, chert and graywacke. Marine(?).

MARINE GRAYWACKE AND MUDSTONE (Lower Cretaceous; A 1 b i an)--Cl asts o f volcanic rocks.

UNDIVIDED GRAYWACKE AND SILTSTONE (Upper and Middle(?) Devoni an)-- Dark gray phyll i t e and polymetamorphosed chl ori t i c wtas i l t s tone , T h i n beds o f marble i n upper part. Undivided u n i t a1 so i ncl udes metagraywacke fa r ther north {Map B) .

UNNAMED CHLORITIC AND CALCAREOUS METASEDIMENTS (Middle(?) Devonian)-- Brown and gray weathering partly calcareous sl ate and phyllite. Polymetamorphosed.

PHYLLITE AND GRAYWACKE (Devonian(?) or younger)--Dark gray phyllite and f ine-grai ned 1 ithic wacke. Sl i ght ly metamorphosed,

U N D I V I D E D CARBONATE ROCKS (Devoni an(?) or younger ) --Marble and cal c- s i l i c a t e hornfels.

Igneous Rocks

VOLCANIC ROCKS (Quaternary or Upper T e r t i ary) - -Fl a t - 1 y i ng f 1 om o f olivine basa l t ,

FELSIC AND INTERMEDIATE VOLCANIC ROCKS Paleocene) --Porphyr 1 t i c f 1 ows, brecci a, conglomerate and t u f f .

GRANITIC ROCKS (Lower Cretaceous) --Porphyri ti c quartz monzani t e ; granodiorite and monzonite.

ULTRAMAFIC ROCKS (Jurassic t o Mississippian)--0phiolitic assemblage o f serpentinized peridotite and dunite t h r u s t over volcanic rocks {TrMv) . Jurassic K/Ar ages may da te thrusting rather than pretol i t h (Patton and others, 1977).

R Mv VOLCANIC ROCKS ( T r i a s s i c , Permi an, Pennsylvanian, and M i s s i s s i p p i an) --Pi 11 ow basa l t , d i abase and gabbro; che r t and che r t y mudstone; l imestone.

Metamorphic Rocks

D v VOLCANIC ROCKS (Upper and Midd le (? ) Devonian)--Mafic greenschis t .

qms UNDIVIDED QUARTZ-MICA SCHIST (Precambri an ( ? ) , 1 ower Paleozoic ( ? ) , Devonian(?), and M iss i ss i pp ian (? ) ) - -Quar tz -mica sch is t , c h l o r i t e s c h i s t and minor q u a r t z i t e . Lower greenschis t t o almandine-amphibol i te fac ies ; a n d a l u s i t e - c o r d i e r i t e ho rn fe l s near Cretaceous g ran i tes .

csm UNDIVIDED CALCAREOUS SCHIST AND MARBLE (Precambrian(?) t o Devoni an(? ) )--Brown-weathering muscov i te -quar tz -ca lc i te s c h i s t in terbedded w i t h sch is tose marble and quartz-mica sch is t .

SOURCES OF MAP INFORMATION

Map A, Yukon c ross ing t o Wiseman I

Brosge, W. P., and Reiser , H. N., 1964, Geologic map and sec t i on o f t h e Chandal ar quadrangle, Alaska: U.S. Geolog ica l Survey M i s c e l l aneous Geologic I n v e s t i g a t i o n s Map 1-375, sca le 1:250,000.

1971, P r e l i m i n a r y bedrock geolog ic map, Wiseman and eastern Survey Pass quadrangles, A1 aska: U.S. Geolog ica l Survey Open-F i l e Report 71-56, 2 sheets, sca le 1:250,000.

~ r o s ~ ; , W. P., Reiser, H. N., and Yeend, Warren, 1973, Reconnaissance geolog ic map o f t h e Beaver quadrangle, A1 aska: U.S. Geolog ica l Survey Miscel laneous F i e l d Studies Map MF-525, sca le 1:250,000.

Chapman, R. M., Weber, F. R., and Taber, Bond, 1971, P re l im ina ry geolog ic map o f t he Livengood quadrangle, Alaska: U.S. Geolog ica l Survey Open-File Report 71-66, 2 sheets, sca le 1:250,000.

I

Chapman, R. M., Yeend, Warren, Brosge, W. P., and Reiser, H. N., 1982, Reconnaissance geo log ic map o f t h e Tanana quadrangle, A1 aska: U.S. Geolog ica l Survey Open-File Report 82-734, sca le 1:250,000.

Patton, W. W., Jr., and M i l l e r , T. P., 1973, Bedrock geolog ic map o f B e t t l e s and southern p a r t o f Wiseman quadrangles, Alaska: U.S. Geolog ica l Survey Miscel laneous F i e l d Stud ies Map MF-492, sca le 1:250,000.

Patton, W. W., Jr., T a i l l e u r , I. L., ~ r o s ~ ; , W. P., and Lanphere, M. A., 1977, P re l im ina ry r e p o r t on t he o p h i o l i t e s o f nor thern and western Alaska, in Nor th American Oph io l i t es : Oregon S ta te Department o f Geology and Minera l I n d u s t r i e s , B u l l e t i n 95, p. 51-57.

CORRELATION OF MAP UNITS

Map B Wiseman t o Toolik

r 1 Metamorphic 1 Igneous I Sedimentary 1 I rocks I rocks I rocks I

} QUATERNARY

CRETACEOUS

Cretaceous

JURASSIC

i' """an

I

t Upper o r Middle Devonian

j Middle Devoni an

) TRIASSIC

\ PERMIAN PENNSYLVANIAN

) KISSISSIPPIAN

' DEVONIAN

SILURIAN

ORDOVICIAN

CAFIBR IAN

PRECAMBRIAN ( ? ) I I

DESCRIPTION OF MAP UNITS

Map B, Wisenan to Toolik

Sedimentary Rocks

UNDIFFERENTIATED SURFICIAL DEPOSITS (QUATERNARY) --S hown only I n the largest valleys.

COLVILLE GROUP (Upper Cretaceous)--Sandstone, shale and tu f f . Mostly nomarine. Exposed thickness about 60 m.

NANUSHUK GROUP AND TOROK FORMATION (Upper and Lower Cretaceous; Cenmani an and A1 b i an)--Nanushuk Group: congl merate, sandstone and shale; fluvial and shallow marine; thickness a t least 600 rn. Underlying Torok Formati on: marine shale and s i 1 tstone; more than 130 m thick,

FORTRESS MOUNTAIN FORMATION Lower Cretaceous; A 1 b i an)--Pol ymi ct conglmcrate, wacke, siltstone and shale. Marine and nomarine. Thickness 1300 rn,

OKPIKRUAK F O R M U I O N (Lower Cretaceous)--Rhythmically-bedded siltstone, graywacke and cangl merate. Marine. More than 600 m th ick .

KONGAKUT FORMATION (Lower Cretaceous) --B 1 ack shale and s i 1 tstone; f l o a t t n g chert pebbles i n l o w e r part. Marine, More t h a n 300 m thick,

KONGAKUT FORMATION AND KINGAK SHALE, UNDIVIDED (Lower Cretaceous and Jurassic)--Black shale and siltstone. Marine. As much as 700 m th ick ,

SHUBLIK FORMATION, OTUK FORMATION, SAOLEROCHIT GROUP, LISBURNE GROUP AND KAYAK SHALE UNOJVIDED ( T r i a s s i c , Perrnjan, and Carboniferous)--Shublik Formati on: black calcareous phosphati c shale and s i 1 tstone and gray limestone; marine; 30 t a 150 rn th ick , Otuk Formation: varicolored chert 1 atera1 ly equivalent t o Shubl ik Formation. Sadlerochit Group: siltstone, shale, sandstone and limestone; marine in this area; about 500 m thick. Lisburne Group: gray cherty l imestone and do1 omite; marine; about TOO t o 1000 rn thick. Kayak Shale: black shale, 1 irnestone and sandstone; marine; about 300 rn thick.

L 1 SBURHE GROUP, KAYAK SHALE AND KEKI KTUK CONGLOMERATE UMDIV I DED (Pennsylvanian and Mississippian)--Pennsylvanian part o f Lirburne Group i s t h i n t o absent in t h i s area. Kekiktuk Conglomerate: quartzite and granule conglomerate about 10 m thick present only i n southernmost outcrops, where it under1 i es Kayak Shale and rests unconformabl y on Lower Paleozoic racks.

Dk KANAYUT CONGLOMERATE (Mississippi an ( ? ) and Upper Devoni an)--Quartz1 te , sandstone, conglomerate and gray to red shale and s i l tstone. F l u v i a1 ; deposited by southwestward flowing streams. About 1000 m thick; absent where Keki k t u k Congl merate rests on Lower Paleozoic rocks.

Oh NOATAK SANDSTONE, HUNT FORK SHALE AND BEAUCOUP FORMATION UNDIVIDED (Upper Oevoni an)--Mostly dark gray shale and s i l tstone; interbedded wacke jn upper par t ; some reef a1 1 imestone and conglomerate i n 1 ower part ; mi nor sandstone throughout. Marine. Upper part consists of prodel t a i c and shore1 i ne deposits gradational i n t o Kanayut Conglomerate. About 1500 to 200Q m t h i c k ; absent where Keki ktuk Congl merate rests on Lower Pal eozaic rocks. Metamorphosed t o s 1 ate and phyl 1 i t e i n southern part o f area.

Dg UNDIVlDED GRAYWACKE AND SILTSTONE (Upper and Middle I?) Devoni an )--Dark gray and gray-green slate and phyllite, meta-graywacke with m a f i c rock cl asts , and chlori t i c meta-si ltstone; t h in f o s s i 1 iferous Upper Devoni an 1 imcstones i n upper part. Pol ymetamorphosed.

Dc UNNAMED CHLOR ITIC AND CALCAREOUS METASEDIMENTS (Middle(?) Devonian) -- Green, red, purple and dark gray slate and phyll i t e ; brown and orange weatheri ng calcareous sl ate, met asandstone and rchi st; gray marble. P o l ymetamorphosed.

Pa UNNAMED VOLCANIC CONGLOMERATE {Devonian(?))--Sheared rnafic pebble conglomerate and breccia grades i n t o volcanic phyllite,

DSs SKAJIT LIMESTONE (Middle Devoni an and S i l uri an)--Gray, non-cherty marble, and gray and orange dolomite. As much as 600 m thick.

Pzcs UNNAMED CALCAREOUS METASILTSTONE (Lower Paleozoic)--Gray and gray-green partly calcareous sl ate and metas i 1 tstone, and gray t h i n-bedded mfcaceous l imestone. Weathers brown and orange.

06v UNNAMED VOLCANIC AND SEDIMENTARY ROCKS (Ordovic i an and Cambri an (? ) )-- Andesit i c and basal t i c pyroclastic rocks and volcanic conglomerate; black and green phyl l ite; s i l l s and dikes of gabbro and d ior i te .

6b UNNAMED B U C K METASILTSTONE (Cambri an)--&l ack, pyritic metasil tstone and phyl 1 i te; t h i n f ossi l i f eraus 1 lmestone 1 ocal 1 y i n upper part. Includes many small unmapped mafjc s i l l s and dikes.

Igneous Rocks

Dv UNNAMED VOLCANIC ROCKS (Upper and Middle( ?) Devoni an) --Gabbro and d i abase s i l l s as much as 100 m thick; pillow basalt flows 10-80 rn thick. Metamorphosed to greenstone and greenschist.

Pzg GRANITIC ROCKS (Devonian(?) and/or Ordovician(?))--Gneissic granodiorite and quartz monzonite with conflicting Ordovician, Devonian and Cretaceous i s o t o p i c ages.

-.

Metamorphic Rocks

qms UNDIVIDED QUARTZ-MICA SCHIST (Precambri an ( ? ) , Devonian(?) and Mississippi an(?) )--Gray t o black, coarse t o fine-grained quartr- muscovite-chlorite-albjte schist , locally with b i o t i t e and garnet. f ncludes some maf i c greenschi s t . Polynetamorphosed. Ages are from D i l Ion, Hamj l ton, and Lueck (1981) and Nelson and Grybeck (1980).

csm UNDIVIDED CALCAREOUS SCHIST AND MARBLE (Precambri an( ?) to Oevanf an(?) ) -- Brown weatheri ng muscori te-quartz-ca1 ci t e sch is t interbedded w i t h schi stose marble and quartz-mi ca s c h i s t . Polynetamorphosed. A 1 tered to calc-silicate hornfels around granitjc rocks Pzg.

SOURCES OF MAP INFORMATION

Map 8, Wiseman t o Toolik

5rosg6, W. P . , Reiser, H. N., Dutro, J. T., Jr., and Detteman. R . L., 1979, Bedrock geologic map o f the Philip Smith Mountains quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-8798, 2 sheets, scale 1:250,000. I

Brosge, W. P., and Reiser, H. N., 1964, Geologic map and sect ion o f the Chandal ar quadrangle, A 1 aska: U ,S. Geologl cal Survey M i scel I aneous Geologic Invest iga t ions Map 1-375, scale 1:250,000.

~roscjh, U. P. , and Reiser, H. N., 1971, Prel i m l nary bedrock geologic map, Wiseman and eastern Survey Pass quadrangles, Alaska: U. S, Geological Survey Open-F i l e Report 71-56, 2 sheets, scale 1:256,000.

6rosgk, W. P., Reiser, H. N., Dutro , J. T., Jr., and Nilsen, T. H., 1979, Geologic map of Devonian rocks In parts of the Chandler Lake and Killik R i v e r quadrangles, Alaska: U.S. Gealogical Survey Open-File Report 79- 1224, scale 1:200,000.

D l 1 Ion, J. T., Hamll ton, W. $., and Lueck, Larry, 1981, Geologic map of the Wiseman A-3 quadrangle, Alaska: Alaska D l v i s i o n of Geological and Geophysj cal Surveys Open-Fi 1 e Report 119, seal e 1:63,360.

Nelson, S. W , , and GryGeck, Oonald, 1980, Geologic map o f the Survey Pass quadrangle, 8rooks Range, A ? aska: U. S. Geal ogical Survey Miscel 1 aneous F i e l d S t u d i e s Map MF-1176-A, 2 sheets, scale 1:250,600.