Zinc-Copper Deposit at Tracy Arm Petersburg District Alaska By H. R. GAULT a d R. E FELLOWS

ZINC AND LEAD DEPOSITS OF SOUTHEASTERN ALASKA

G E O L O G I C A L S U R V E Y B U L L E T I N 9 9 8 - A

A study of the Tracy Am =in c-co@er prospect

UNITED STATES GOVELNMENT P R I N T I N G OFFICE, WASHINGTON : 1945

UNITED STATES DEPARTMENT OF T'HR INTERIOR

DongIan M C K . ~ . Sumtaw

PREFACE

AH 8 pact of ita investigatimw in southeastern Blmh between 1941 and 1948, the U. S. Geological Survey ~tudied in d e t d eight depiteJ that contain sphderite or ~phalerite and galena aa the predominant. ore minerds with lesser mounts of chalcopyrite In. a few deposihs. These d o p i & me at Tracy Arm, Groundhog Basin, Glacier Basin, the Idre c h awst of Virginis Lake, Berg Basin, Moth Bay, Ma- honey Creek, snd Dora Lake. These depasita we d d b d ia the ~ e v d chapters of this bulletin.

Zino and lead minerals me nbo known or reportsd at the Hydm district, Whiting River, and Farragut River on the maidand, Corn- w d i s Penhula on Kuiu I s h d , the K ~ k u Ideta north of Kuiu Is3 Zasd, ChoImondeley S o d and Beaver Mountain on Prince af Wda L b d , Woewodski IeIand, Taylor Creek an Kupr-of M a d , and Coronation Tdmd. Some of these ocmmenca are noted elsewhere h the g€d0g€d XikT8hW. To data (1953) no major zinc or lead deposit in Alaska h corn%

inte production. Lead has been produced as a byproduct at the BI~~ka-Juneau gold mine and from the R i v d d e mine, Hydm district. h 1947 md 1948 s h u t 70 tans of zinc and lead concen- tat- were shipped from Mahaney Greek ta Kellogg, Idaho.

m

CONTENTS

h ~ s 1. GwllMa map of vein and pita, Tracy Arm sinesopper de~i t , , , - - , , , - , , - , * - - - - , - - , , , , Inpocket

2. GeoloRic and M p o p p h i a m ~ p of part ot T w y Arm and vicii~itg-, ,-,, -- -. ..,, . -,- ---- --- - -,, In pocket

3. Geolo~io map of the ares at the elbow in Tracy Arm showing claims,, , , ,,,-, ,, ,,---=,- ,----,, - -- - - , - - - , , In pocket

Rawm 1. Sketch map of muthemubrrt klaske ,--,.,,,---,-,,,,,------ 2 2. Equal m a net showing distribution of joint pales from Tracy

ZINC AND LEAD DEPOSITS OF SOUTHEASTERN ALASKA - ZINC-COPPER DEPOSIT AT TRACY ARM,

- PETERSBURG DISTRICT

The zinc-eopper deposit at Tracy Arm lien in a nequem mf o b m r p b i o mka that 5mk the wagt gide of the Crwat Rnnge batholith. Three zones of metamorphic rocks are reeogbed in the a m : a w n e of lighhdored brown mhisb; a mne of dark-grmn mhists, black phyllitee, and gray-green aohista; end a zone of l i g h t - p n chlorite achiats. In sddition to the Coaat Range batholith s lmgo quartz diorlte sill and numerous quart% diorite and mafie dlkea have intruded the metarnorpbio mcks in tbis m a . The s i n m p p e r deposit ia a m placement vdn in a 8hw Bone that paraliela the folktion of the metamorphio rocks, Tha d e m t is partially m d for a length of 1,140 feat, but the greatest amount of me Is confmed to the ~outbern 830 feet. The vein averegea 4.8 feet wide over the 8Wf& intervd, bat the depth to whfah it extanda is not known. The averBge g r d e of ore, ae calculated from avaihtble analyim, is 3.9 percant of h a , 1.5 percent of copper, 0.013 ounce of gdld par tan, and 0.76 ounm of silver per ton. Reeervea of ore nre =timated to tm about 40,000 tom per 100 feet of depth.

Tracy Arm is s long and i m p 6 v a fiord extending inland from Eokham Bay, B wide d e t on the mat d e of Sltephens J P v abut 47 mars southomt of Juneau. (See fig. 1 m d p1. 2.) The area is characterized by ateep slopes, n thick growth of bmh m d timber, and generally rugged relief with peah 8s high aa 6,600 feet. Timber- line is at an altitude of abut 2,500 feet.

During 1944 s study of Ehe Tracy Arm zinwppm prospect waa mads ss part of the atrategio m i n d s p~grrrm in Alaska of the U. S. Geologid Sumsy. The geology of the zhwapper deposit and the general geology of an are^ of about 50 s p m miles surround- ing $he depomit were mapped. The writam were in the area from June 0 to September 14, 1944. dues and psrt of July were spent in detailed mapping of the deposit and it9 immediate viciniw. The remainder of the fidd e w n was spent mapping the metamorphio mcka that extend southwd from the deposit t~ a point on the norheast shore of Endiwtt Arm opposite Sumdum Island md including Sumdum and Bushy Islands.

2 'IINC ANTI LEAD DEFOBm OF BOUTHEABTERM ALASKA

130.

mamm l . 4 k e t c h map of muthenatem A l ~ k a ~howing location of same l e d - ninc depoeita.

Thie invmtigation included detailed mapping of 23 ~urf808 pita, one of which includes a 16foot shaft, nnd locating the north and muth b i t s of the deposit. (See pl. I). All the old pits were daned oat nnd edarged, the shaft waa bailed out, and 5 ngw pita were dug. Sampling of the deposit by previous investigatars was coneidered adequate and therefore no ore srsmpleg were collected for laboratory analpis by the miters, Detded mimcopic studiee were made of the vaeious rock: types, but only part of thme dats, Bre included bere.

ZtNC-COPPER DEWBIT AT TRACY ARM, Urn 3

Momation on some of the older mining properties in the area m d summaries of the general geology of southeastern Alaska are available in reports by Spencer ' and by Huddington and Chapin. W. S. Twenhofel and G. M. Flint, Jr., of the Geological Survey,

visited the writera in Jdy So assist in mrt,rrin phwes of the work. Harry Townsend, the owner of tho property at this t,ime, spent a week in ddy at the writers' carup and gr~teful acknorrloclgment i made to him for many constructive discussiona in thc licld. TItc hospitality and cooperation of Ernest ICohlhasa, of Harbor lslrtnd, is greatly appreciated.

GEOLOGY

The area in the vicinity of Tracy Arm is underlain mainly by a p u p of northwest-trending metamorphic rocks that flank the west edge of the Coast Range batholith. (Sec p1. 2.) Theso mcks are here subdivided into three zones: an eastcm zonc of light-brown schists; a central zone of dark-green schists, black phyllites md gray-green schiats; and a western zone of Iight-green chlorite schiats. The bound- aries, bmed in part on lithology and in part on degree of metamorphism, are not slmrply defined.

The metamorphic mcb are b o d e r d on the east by quartz diorito gneiss of the Coagt Range batholith. Siiicic dikes and sillsl that seem to be genetically associated with tho batholith also have intruded the metamorphic rocks. Lampmphp dikes are the youngest igneous rocks in the mca and intrude both tho quartz diorite gneiss and the schishs.

T h e easternmost of the three zones of metamorphic rocks consists predominantly of light-brown achists int crbcdded with minor amounts of dark schists and gneia~m. Thcse brown schists are composed largely of quartz-biotite-feldspar, quarh-muscovite-biotito, and quartz-muscovi te-feldspar vmirtips. ArnphiboIitcs mid dwk phyl- lites are present locally, Some of the phyllitn handa contain scveraI percent of sulfide minerals, principally pyrite and pymhotite.

S m w discontinuous marble beds crop out near the contact of the mctamorphic rocks with the batliolith bout R miles muth of the elbow of Tracy Arm. Carbonate schists and very impure marble crop out farther to the south and are well exposed in the long valley on lthe east shore of Endicott Arm opposite the middle of Sumdum Island. (See pl. 2.)

1 Bpenear. A. O., lBM, me Juneau gold belt, Alaska. In ConMbuthm to -mk pdogp, IW, by 8. F. Emrnona and C. W. !&yes, U. B. OmI. Bd. m. p.

t Buddlnuton, A. F., snd Chapin, Thmdmp, 1628, Wogpand mlneml dqmalbat mt-n Alsskb: U. 8. O m l . Bwmp BUR. 800.

The central zone is slightly more thm a d a wide. T h e metamor- phic rocks me more hetemgeneoua and generally darker than the light-brown schisb of the e a s h zone. Amphibole, amphibole- biotite, ampbibole-pleoclase, quartz-mica, quartz-feldspar, and mphiboIe-garnet-feldspar schisb form the bulk of the rocks in this zone. A few of the garnet-bearing schists tankain quartz and calcite lenses and pods many of which are from several inches to eeverd feet long and from 1 to 6 inches thick.

Chlorite, ddoritEepidotecarbonate, cbhrite-q~arhz, amphihl* chlorite-biotite, and amphibole-chlorite schists the dominant rock typea in the weselternmost zone. Interdated with the schiats am narrow bands of black phyllite and quartz-mim, quartz-feldspar, amphibole-feldapw, and mica schists. Many of the T O C ~ in tb zone contain qu- veins ~bnd lenses some of which p d e I the foliation and range up to severaI feet in length.

1C)mom ROCKB

The ignmue rocks in the Traoy Arm area indude the quartz diorite gneiss of the Coaat Range batholith, the sills and dikes gene t idy msodatsd with it, and the younger Iampmphyre dikes that cut both the Coast Range intrusive masses and the metamorphic rocks. The weatern edge of the batholith form the emtern limit of the

zune of metamorphic rocks. The gneiss is moat cumonly a came- gmined rock cornpod of quartz, biotite, hornblende, and plagio- idme, with mmmry orthoclase, sphene, apatite, and magnetite. Nuemus modium- to ha-grained dikes, mostly quarts diori-, alaskites, and a few pegrnatites, have intruded the rnetamorphia rocks. A thick quartz diorite dl m p e out just south of the elbow of Tracy Arm and-about 2,200 feet west of the contact between the metamorphic rocks and the batholith. The intrusion of this sill probably was an important factor in the genesis of the or# deposit.

Schistaae in cluaions are numerous within the b~tholith, particularly near its western border. These inclusions reach a m h u m length of several feet but most of them are only a few inches long. The inclusions are condstently dined parallel to the foliation in the batholith.

Within the quartz diorite intermediate andmine is the moat &bun- dmt mineral. Moderate zoning of the plagiodase k charactmistic throughout the quartz diorita ma=. The other essential minerds in oder of decreasing abundance are hornblende (TW. pawsite), biotite, and quartz. Accessory constituents are orthoclam, sphene, apatiM, and magnetite. Secondary minerals are adcite, chlorite, mlci te, and epidote. Orthoclase is abundant enough in a few specimens to permit $hem ta be classified as grmodiorites although the distinction is slight

ZINGCOPPER DEPOBIT AT TRACT ARM, ALhSKh 5

end only locally spplicable. The average of the modes of represent- ative m p l e s selected in 1944 irorn the batholith in the Tracy Arm area compares closely with the mode detamind by Buddington and Chapin for five quartz diorites from mutheastern Alaska:

Corn* of tht amage d mode8 (in p a d of rupm&iw g w r i 2 diwite aamvlea

16 aampbt, I@& - e&--hl&ka- ' T t a i ~ A m area Det~rmlned by (Dotnrmlned h BaddIngGon and R. F:. el lo wry r h a ~ l n l

The quartz diorite in the thick sill west of the ore deposit does not differ appreciably from that in the parent mass. Hornblends lathe, plmdaae lath, biotite flakes, and small quartz augm aro generally well dined,

Compositional and textural variations are seen near m d at the contact of the batholith with the metamorphic rocks although some of the exposed contacts are &ply defined with no affected border zono. The variant facies include a dark medium-grained rnsssive rock composed wholly of hornblende and d c i c andmine, and an extremely coarse-grained massive rock composed of hornblende c r y - ta Ia with a maximum length of 18 millimeters set in a white mstrix of Goarae intexmadiate a n d b e crystals.

The numerous dikes of inGermediate to acid mmposition that cut the metamorphic ro& are probably Merentiatea from the main quartz diorite magma. They include diarites, quartz diorites, ala* kites, and a few s d pegmatite stringers. Tbm dike rocks are

.medim- to he-grained gray aggregates of plagrodw, hornblende, biotite, quartz, apatite, and sphene. Alteration products am cldorite, aexicib, and &cite. The dikes that cut the zinc-copper ore body are m e t d i d with minor amounts of chdcopyrite, aphderite, and pyrrhotite. T h e dikm seldom ex& a few feet in tl~iclmess, but are locally ss much as 25 feet thick and wmmanlg intersect each other.

The gumh diorite dikes can be separated into two varietiee on t h ~ basis of the praence of hornblende and the composition of the feld- spar. One variety ia hornblende-rich with mlcic andesine; the other is lacking in hornblende md contains intermediate andesine. ,

FoZia tion, which is nearly parallel to that of the metamorphic roch, is moro noticeable: in the diorite dikes thm in the quartz diorite dikes.

1 Buddhgtw, A. B., and Ohpln, l bodom, op. dk, g. 212 (item S in table).

&&te dikes cut tho metamorphic rocks, the sU, and probably dso the main batholith. They contain sodic plagiodase, potash feldspar, and quartz hut me practically barren of dark minerals.

The basic d i k ~ are light- to dark-green very h e to medium- grained larnprophyres. B m m hornblende and pIagioclase are the principal primary minerals of the bnsit: dikes along with minor amounts of p j ~ i w , sphcne, quartz, and magnetite. Epidota, sericite, chlorite, and calcite aro alt~rabion prodacts of the hornblende and pl&ocIase. The maximum thickness of the dikes is 30 feet, but thicknesses ranging from 1 to 2 feet are more common. Thc thicker dikcs h ~ v o chilled margins; and some are porphyritic.

Quartz dioritie dikes, most of which are near the bordcrrs of the largo intrusivr masses, are most abundant. The lamprophprcs ars aocond in abundance and crop out, principally in the northern h Jf of tho area.

STBWCTURE

Tho atmcture in the Tracy A m area conforms in general with tho major featuros known throughout southeastern Alaska. The rcgiond trend of the rocks is northwest. Lineations in the gneiss show n con- sistent, and steep northward plunge. The contact of the batholith with the metttrnorphic rocks is slghtly discordant M tsrvenlod by a comparison of the attitudes of foliation in the quartz diorita and in the schiets. The discordance also becomes apparent over a distance of several miles by an increase in width of tho emternmoat metamorphic rock units and the appearance of new memben toward the south,

Isoclinal folds are mnmon in thc metamorphic rocks. The fold axes plunge somewhat more steeply southward in the northern half of the mapped area than in the southern half. In tho northern part of the n r e ~ the foliation in the schists strikes N. loa-15' W., whereas in the southern half the strike is mom westprly.

The metamorphic rocks are largely recrystallized. Tbickening'in the m t a of folds is prominent in quartxitcs as well as in phyllites and in many places amount,s to 200 percent in the quartzites and several times that amount in less mmpctcnt rock units. The clirection of the stretching of quartz grains and pysito cubcs is generally parallel ta the fold axes although discr~pancjes occur.

The dominant set of joints in the aroa strikes N. 45' E. at an angle of about 65' to the strike of the foliation and dips steeply northwest. (See fig. 2.) Whoraver detailed ~ t u d i e s have been made in the Wrangel1-Ravillagigedo belt of metamorphic rocks, this set of join& predominates. The pattern of joints in the quartz diorite gneias - canforms to that in the schist.

ZINC-COPPER DEPOSIT AT TRACT ARM, AWL-

mom* z-?Zqual ma plot d l e ~ ~ d pka d Wut p h msermrsd &t W y Arm a d vlchity.

ZINC-COPPER DEPOSIT

The eincm~pper d&t is on a poorly defined topographic bemch about 1 mile south from the ~ l b o w md on the east side of Tracy Arm at m altitude of 780 to 850 feat. (Sea pln. 2 and 3.) A trail 1 mile long legds to the deposit from the mouth of a stream that flows through a prominent notch and empties into Tracy Arm about 800 feet muth of the elbow.

8 ZINC AND LEkD DElPOSIT8 OF f 3 0 U T H X m R N AUSKA

Roehm,' wha viGted the property in 1942, hm m r d e d that the deposit h reported to have been discovered by AIBI ButEerbaugb in 1016. Buddington' examined the property briefly in 1923 and s h M that it wras relocated in 1822 and 1923 by Eugene Own8 as the NgIeckd Prize. The deposit waa again relomted by Harry Town- send in f 943. Samples were cut by Roehm in 1842 md by the U. S. Bureau of Mines in 1943. J. C. Reed md W. S. Twenhofel, of the Qmlogical S m q , spent 3 days at the deposit in 1943, and it was on t3reir remmmendation that tbe present work wm performed.

Field work leading to this report entailed the mapping of 23 surfam pits and dehmining the north and south extent of the deposit. (See p1. 1.) All the old pih were clwd out and enlarged, the shaft m s bded out, and 5 new pita were dug. Rm-y Tomend returned to the d e p i t for s few days in September dtm the miters had left and l a w reported thtbt h0 dug a long trench normal to the strike of the vein at the shaft.

Wte, pphotite, and much less abundsnt chalcopyrite, ephalerib, and magnetite are d k h t e d through a l q e pwt of the section of

, metamorphic rocks at Tracy P+rm and Endicott Brm. Mast of the rocks that contain disseminakd 8uKde mineral8 ara blwk phyllites md hght-mlomd quartz-rich whi~ts. Many md quartz v e h in the metamorphic rocks cuntain poda and disseminated graias of pyrite and pymbotite, but only at the Tracy Arm zhmmpper prospect are the, sulfide minerals sufficiently concentrated ta magfituta an ore deposit.

DE10-01P

The zinc-copper deposit is a mplament vein in a shear zone that parallels the foliation of the country rock. The ahear zone, which laan be t r d dong iB strike to a point 75 feet muth of the muthem limit of the vein, is in the eastemmost Mt of lighhlored schists. Northwmd from the vein the shear mne is marked by a poorly d e h e d gully that leads to the ahore of Tracy Am. Tbis ebear zone, as well ae others in the area, is &tmct&ed by

a m d tight drag and shear folds, granulated muntrg d, brecciation, and offsetting of dikas and beds. T h e shem zon~ that contains the

grades along hhs strike into unghewod country rock. The w a h of the shgsr mne me f d y well d e h d ; the width of the zone, n h m rneaaurable, ~..angea from S ta 12 feet. The zinc-mpger vein can be tmced far 1,240 feet hoPieontdy and

110 feet vertically. The northem 3 10 feat mn~isb of a &continuow band of d 6 d e minerals 4 to 6 inches wide. Within the 830-foot

' * R-, J, c., IW, fnveangethg fu mum&m~ M far I W ~ : MW ~egt. Mha [Unpnblhhed r8wrt.l

B n d m , h F., lw, Miasral tn-bw 1D #o-h A U 4 h U. & -w. B d m3. p 1st-181.

ZINC-COPPER DEPOBIT AT W C Y A m , ALbBRA 9

sontbem portion the vein mnshts of masgive and bmded ore, with &&tIy m e t d b d qu&s diorite dikm, alaaldte dikes, and qu&z ~ e i n s .

SphJ&te snd pymhotitite are concentmtd largely in the central psrt of the vein and is designated as rn-i~e ore. A few a m d barren blo& of &t occur within the mwive ore.. The m i v e ore H Ji ta 315, feet wide (pl. I) end comists uf an aggragate of aphalexita, chal- mpyriter and pymhotite togo thm with a very minor amount of galena in a, matrix of hght-colored silicate minerals.

T h e mmive ore is generally bounded by baudd ore that ntngm in width from 1 to 12 feet, The banding ia produced by slight varia- tions in grain size and camponition in the l ighholod quartz-rich mhbta. Banded ore is distributed most cumonly on both sides, of the massive ore. The minerals in the banded ore w e the same aa t h m in the m d v e om, but chalcopyrite i the predominant d d a 'I'he ore minds, owing to selective replacement, are canfined to thin lamellae in the schist. The amount of sulfide minerals in the banded w e decre~rses outwsrd from the center of the vein, and not all the bmded material can be d d aa ore.

S e v d quartz diorite and daskite dikes cut the Elheer zone, The margins of the d&ee are slightly metallized where they me in inntact with the vein, and locally the daskite bodiw contain sufficient amounts of sulfide minerals to constitnte banded ore.

A brief atudy of polished sections of the ore shorn that pyrrhotite was the h t s&de mineral to ba deposited. It wm followed by sphelmite, chdmpyrite, snd galena. Quartz, mica, and feldspwa form the gangue and together constitute 50 percent or more of the ore.

Chalcopyrite fik s e v d smdl fractures in the win near the shaft at pit 12. The ratio of sphalerite to chslcupyrite here is roughly 2 to X . Zn gemerd the proportion of ~phalerite is slightly higher in the &ve ore than in the bmded ore. Pyrrhotite ia s minor constituent except in the d e w central part of the massive om. Thia cloncantration of pyrrho ti te is thought t~ represent s replmd zone of gouge. Galena ia sperse and was identified only in polished sectiom of samples from pit 12 8011th of the ahaft. Pyrite impregnatm the country rock for 10 to 15 feet on either side of the shear zone, ~pecial ly near the north- ern portion of the deposit.

The best massive ore 13 in the central part of the southem 830 feet of the vein where the ambinad width of massive and banded ore ranges from 2 ta 12 feet. The vein is chw~terized by pinching and swelling along ih strike. Ita vertical extent is not known, but, bemuse the ore at the d a c e is mntinuoua, it aeerns reltaonable that the ore may extend at least a few hundred fset helow the surface.

10 ZINC AND LEAD DEPOSXTB OF BOUTHEABTERN ALASKA

The ~olutions that impregnated the shear zone m d formed the vein are probrthly genetically related to the quartz diorite sill that mps out BOO feet west of the ore body. (See pl. 3.) The vein is in that part of the shear zone nearest the sill.

Other shem zones with t.he same general topogrsphic exprwion and length as the one mntaining the vcin are present in the surround- ing area. Most of these me dso p a d e l to the foliation of the meta- morphic rocks, but a few strike northeastward. One of the zones lies 100 feet west and pamuel ta the zone which contains the vein. A b u t 1,500 feet of the trail leading from the deposit to the beach lies in a prominent notch which is the trace of anobhsr zone.

Pyrite, p yrrhotite, and cbalmpyrite are only slightly more abundant in tho hear zones than in the unshcared country rock, Bands of material aeveraI inches wide and a few tens of feet long containing 10 to 15 percent of sulfide minerds ara exposed in other $hear zones near the deposit .

BEBgaVES

Severd in~estigators have sampled the deposib since it9 discovery in 1910. The results of their malpm m a shown in the table. The writem did not attempt to sample. the deposit thoroughly because the earlier analpeg are believed sddent in number and dltribution to give a remonably accurate estimate of the grade of om. The weighted average of ore, calculated from the andyes given in the table, omitting several valu~s obviously mu& higher than the average, is 3.2 percent of zinc, 1.5 percent of copper, 0.013 ounce of gold per ton, ~ n d 0.75 ounce of dver per ton.

The tannage of ore in the vein is classed as i n f d ore and ia mti- mated to be about 40,000 tans per 100 feet of depth. This figure is based en an aver* width of 4.8 feet, a length of 830 feet, and a con- vemion factor of IO cubic feet of rock per ton. The depth to which the ore extends is not known.

ZINC-COPPER DEPOSIT AT TEMCY ARM, ALASKA 11

~ u ? n ~ t a ? y of aasay d a i a dmmacd fim sample8 l ~ k m d the Tracy Arm aim-capper deposit

Fit no* Caprmr ( m n t )

ziao ~percenn M P M

R ....-....... t ,----,.-..... ..... t . . .............. 7.. - .................. 7 ,. 'I.. .................... P ...................... * ..,...-.-..---,..--- 9.. ................ .... $43 ................-... 10 ..................... 10 ..................... 12 ,....--......_...._ I z ................ .... 12 ..,...-..........-+- 12-,-. ............... 12 ..................... 12- ................... .. 11 .--, ............... I4 ..................... 1 1 ---.---....-....... 15 ..................... 11 ..................... 16 -------+----+- ----- 17 ..................... 17 ..................... 17 ..................... 18 18. .................... 19 ,..............-.-- 20. .................... 81 ..................... a,, ................. L .................

3.m

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3. 87 4.70 4. W 2 Q4 2 4 2 a. r~

1.91 a.20 a a 8.30 L. $8 . I5 1.a 2.52 1.23

I. If I -71

1.86-

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2M 1.53 1.M 1.36 .39 2 92

3.08 22R b.31 4.40 !& 112

8.70

8.w @+& 7. % 6.41 km

10.44 8.64

tam 7 . a .38

b 40 3, a4 8.11

4.40 4. W 3.4B , a 21 1 4 8 1-16

4.17

km

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M

1.10

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1.5-1 1.34 . 7n

8.92 t n o

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-72: Tr. . RO

130 .MI . +El

. a

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.28

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.w 1.00 . ~ l l

so

Mnir.

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Rnehrn. 4.0 I U 3.0 6, 0

3.0 a.6 8 0 LO 3.3 a e CO 4.0 3.8

4-6 8.R a 6

1 0 6-8 7.U

@.Q &I0 9.4

6 7

. 7 8 .1

a7

Mulr. Rwl~rn. Townma. Mr~lr.

T~mmml. h b m . R w d , m O f d . .Vuir. 31ulr. Mu~r.

T o m d . W w h m . M~ur.

~ w h m . Mulr. h111hr.

T o d . n ~ h r n . htulr.

To-nd. Rmhm. Muir.

mu~r.

Mulr. MUW.

MU&.

INDEX

....................... D ~ t l o n d m .... I of d-t ........................ R-10

DfkeweRs;Wmklte ........................ 4S.4 0 lampmphgw ............................. a18 qusrts dlorlte ........................... 4 L & D di~fc..-- -.-+..--+-m.-*--..-----.------

EndimttAm ................................ l . & B

Fialdvcrk ................................... 1 4 . 8 Folds ................................... & 8 FoTietkm ................................ 4,41410

&dmy ..,...........+...---.. ... pb. 1 9

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R B e d , J . C . , ~ ~ m p I e s ~ b y ............. I1 &mvea .................................... tO Roebm, J. U., m m p h c0lkol-d by... ........ 11

Sahish .-__-.--__._------------.-- 8, 4, U, 8, o; pi. 2 Btructure, metamorphia roaka ........... ...,. t i 7 ~~d~-s------+------*----*--*--- a,Lbp, 10

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w-+-gsda belt mebmmhip rocks .............*............... 8

ZPmPPQ mphwunmt ?em -,,.--.......... 8-10 18

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