«/ * rJ ^m * *- ^Ifr ^^ ^*lll ; J^ -life /°- vilR- »° r.- ^ y % * ^ v V" "^ > ,/,^^X y,^A y^.X /&.\/^A * "^ "^ v- s . . , "?> ° » ° <5> ^» * • < •> * ^ , . <$> " ° « o * .v ^» * » i -t • A u *$> * o » » * .Jfe'v V* : ?." ^^ '.1 /k- ^ ^ *y ^+f ^ -.^ *'^. °, '•■•" A u ^"^ c°\C ^ •> ^ 0° .»« V'^^V' '\^ 7 ^ :% \^' V*3\o' %/^:^\/ .. V : ^'* / V *»• v"n^ V ^4* V > '-^ v;* v ^ b ^.-^fe.% £>£&** jfsM&S **>&&>* / *sMik * f; J * X %' v^'V c V^^'/ \' 7 K-\* f ' %'^' / v^-v IC 9104 Bureau of Mines Information Circular/1986 Tin Reconnaissance of the Kanuti and Hodzana Rivers Uplands, Central Alaska By James C. Barker and Jeffrey Y. Foley UNITED STATES DEPARTMENT OF THE INTERIOR Information Circular 9104 Tin Reconnaissance of the Kanuti and Hodzana Rivers Uplands, Central Alaska By James C. Barker and Jeffrey Y. Foley UNITED STATES DEPARTMENT OF THE INTERIOR Donald Paul Hodel, Secretary BUREAU OF MINES Robert C. Horton, Director T Ntf 5 " As the Nation's principal conservation agency, the Department of the Interior has 7 / I responsibility for most of our nationally owned public lands and natural resources. This ■ ^ includes fostering the wisest use of our land and water resources, protecting our fish and , p wildlife, preserving the environment and cultural values of our national parks and / '- historical places, and providing for the enjoyment of life through outdoor recreation. The Department assesses our energy and mineral resources and works to assure that their development is in the best interests of all our people. The Department also has a major responsibility for American Indian reservation communities and for people who live in island territories under U.S. administration. :V Library of Congress Cataloging-in-Publication Data Barker, James C. Tin reconnaissance of the Kanuti and Hodzana Rivers uplands, cen- tral Alaska. (Information circular ; 9104) Bibliography: p. Supt. of Docs, no.: I 28.27: 9104 1. Tin ores -Alaska -Kanuti River Watershed. 2. Tin ores -Alaska -Hodzana River Watershed. 3. Prospecting-Alaska-Kanuti River Watershed. 4. Prospec- ting -Alaska -Hodzana River Watershed. I. Foley, Jeffrey Y. II. Title. II. Series: Infor- mation circular (United States. Bureau of Mines) ; 9104. TN295.U4 [TN271.T5] PREFACE This is one of a series of Bureau of Mines reports that present the findings of reconnaissance-type mineral assessments of certain lands in Alaska. These reports in- clude data developed by both industry and government studies. Assessing an area for its potential for buried mineral deposits is a difficult task because no two deposits are identical. Moreover, judgments prior to drilling, the ultimate test, frequently vary among evaluators and continue to change as a result of more detailed studies. Included in these reports are estimates of the relative favorability for discovering mineral deposits similar to those mined elsewhere. Favorability is estimated by evalua- tion of outcrops, and analyses of data, including mineralogy, geochemistry, and evalua- tion of rock-forming processes that have taken place. Related prospects and the environ- ment in which they occur are subjectively compared to mineral deposits and en- vironments in well-known mining districts. Recognition of a characteristic environment allows not only the delineation of a trend but also a rough estimate of the favorability of conditions in the trend for the formation of minable concentrations of mineral materials. CONTENTS Abstract Introduction Acknowledgments Study area Land status and ownership Location and access Physiography and climate Previous work General geology Placer investigations Sampling methods Sithylemenkat pluton area Northern Ray Mountains area . Investigation of granitic plutons . Sampling methods Sithylemenkat pluton Ray River pluton Hot Springs pluton Fort Hamlin Hills pluton Coal Creek pluton Major-oxide analyses Trace-element analyses Discussion and recommendations Tin placer development potential Lode tin development potential Conclusions References Appendix A. - Geochemical analyses of rock samples . Appendix B.- Sample identification key ILLUSTRATIONS 1. Location of study area and granitic plutons in central Alaska 2. Location of concentrated placer samples 3. Detail of sample locations on east fork of Kanuti Kilolitna River 4. Stream profile of east fork of Kanuti Kilolitna River 5. Broad, alluvial outwash valley of east fork of Kanuti Kilolitna River 6. Geologic map of Sithylemenkat pluton 7. Two aerial views of a structural intersection where chlorite-rich tin-bearing greisen occurs 8. Rock sample location map for Sithylemenkat and Ray River plutons 9. Sample location map for Hot Springs pluton 10. Sample location and geologic map of metazeunerite occurrence in Hot Springs pluton 11. Rock sample location map for Coal Creek and Fort Hamlin Hills plutons 12. Comparison of Kanuti and Hodzana Rivers uplands plutons with Australian "tin-mineralizing granites" . 13. Areas of tin development potential suggested for further placer investigations TABLES Tin analyses, weights, and volumes of placer concentrate samples 7 Semiquantitative X-ray fluorescence spectrometry analyses of trace elements in nonmagnetic fraction of placer concentrates 8 Major-oxide analyses and normative mineralogy of samples from plutons in Kanuti and Hodzana Rivers uplands 16 Average concentration of trace elements in unmineralized rock samples from plutons in Kanuti and Hodzana Rivers uplands 17 Geochemical analyses of rock samples collected in Ray River and Sithylemenkat pluton areas 21 Geochemical analyses of rock samples collected in Hot Springs area 24 Geochemical analyses of rock samples collected in Coal Creek and Fort Hamlin Hills pluton areas 26 UNIT OF MEASURE ABBREVIATIONS USED IN THIS REPORT ft foot ft 2 square foot ft 3 cubic foot g gram in inch lb pound lb/yd 3 pound per cubic yard mi 2 mm square mile millimeter pet ppm yd 3 percent part per million cubic yard wt pet year weight percent TIN RECONNAISSANCE OF THE KANUTI AND HODZANA RIVERS UPLANDS, CENTRAL ALASKA By James C. Barker 1 and Jeffrey Y. Foley 2 ABSTRACT The Bureau of Mines evaluated the tin development potential of the uplands between the Kanuti and Hodzana Rivers from 1978 through 1980. Chemical and petrologic data indicate that local granitic intrusions are generally similar to "tin granites" that contain tin deposits elsewhere. The tin mineral cassiterite (Sn0 2 ) was identified in chlorite-rich greisen from the Sithylemenkat pluton. Greisen zones are located near the intersections of high-angle, linear structural features, and samples contain up to 0.23 pet Sn. One bedrock exposure of greisen is 10 to 15 ft wide. Although some lode mineralization is present, the deeply eroded nature of the region suggests larger tin-bearing cupolas may have existed prior to erosion. Extensive stream gravel deposits have not been affected by glaciation, and potential exists for placer tin deposits. Especially favorable is a large semiclosed basin drained by the Kanuti Kilolitna River. Heavy mineral concentrates collected from surface alluvium in the Kanuti Kilolit- na River valley contained up to 51.2 pet Sn (0.02 to 0.4 lb/yd 3 Sn), up to 5 pet W, up to 0.4 pet Cb(Nb), and up to 0.1 pet Ta. The concentration of heavy minerals is expected to in- crease with depth. Detailed mapping and extensive surface and subsurface sampling will be needed to quantify the mineral development potential of the lode and placer tin deposits in the uplands. ■Supervisory physical scientist. Physical scientist. Alaska Field Operations Center, Bureau of Mines, Fairbanks, AK. INTRODUCTION The Bureau of Mines investigated tin and associated metals in the Kanuti and Hodzana Rivers uplands as part of a program to assess the mineral development potential of critical and strategic minerals in Alaska. (The area studied is shown in figure 1.) The initial investigations were authorized and partially funded by the Bureau of Land Management (BLM) to improve the mineral data base need- ed to develop management plans for the Trans-Alaska pipeline corridor and adjacent lands. Because the United States relies on imports of tin, and because tin is essential to industry, tin is of critical and strategic importance. Alaska has produced tin in the past and currently pro- duces small amounts from placer deposits. Geochemical tin anomalies in the Kanuti and Hodzana Rivers uplands were originally reported by the Alaska Department of Natural Resources (10) 3 and were later reported by the U.S. Geological Survey (USGS) (17) and the Bureau of Mines (2). Sources of the tin anomalies were not located during these studies, and further investigations were recommended. (More details of these and other previous studies are includ- ed in the "Previous Work" section.) The investigation reported here was initiated in 1978 and included a literature search followed by geologic map- ping and sampling of surface exposures of both lode and placer tin occurrences. Field mapping was done during the field seasons of 1978 and 1979. Samples were collected for petrographic study and to determine chemical compositions of associated granitic plutons. Owing to logistical and per- sonnel constraints, the investigation was largely limited to the Sithylemenkat pluton area. Because no drilling or sub- surface sampling was done, the data presented in this report are not sufficient to completely assess the mineral development potential of the area. ACKNOWLEDGMENTS The Bureau of Land Management funded the early phases of this investigation. The U.S. Department of Energy, through the Bendix Field Engineering Corp., Grand Junction, CO, and the Los Alamos (NM) Scientific Laboratory, provided neutron activation, fluorometric, emission spectrographic, and X-ray fluorescence analyses of rock samples collected by the Bureau of Mines. Staff geochemists K. Stablien and W. Averett of Bendix super- vised the analytical procedures on behalf of the Bureau of Mines. K. Clautice, geologist, formerly with the Bureau of Mines, Fairbanks, AK, conducted field studies in 1978. M. McDermott, geologist, also formerly with the Bureau in Fairbanks, directed the 1979 field work. STUDY AREA LAND STATUS AND OWNERSHIP This report concerns lands in and adjacent to the 12- to 24-mile-wide Trans-Alaska Pipeline corridor that parallels the Dalton Highway (fig. 1). The corridor is presently under Federal management according to Public Land Order 5150, but is being considered for transfer to State ownership. Lands east of the corridor are designated as part of the Yukon Flats National Wildlife Refuge. The northern portion of the Kanuti and Hodzana River uplands west of the cor- ridor is part of the Kanuti National Wildlife Refuge. To the south, the refuge is partially overlapped by unresolved Alaska Native selections. The land ownership pattern of the study area is likely to change in the near future as Native and State land claim entitlements are adjudicated. LOCATION AND ACCESS The uplands between the Kanuti River and the Hodzana River drainage systems are 100 to 140 miles northwest of Fairbanks. Except where accessible from the Dalton Highway (fig. 1), the area is best reached by helicopter or float plane. PHYSIOGRAPHY AND CLIMATE The uplands between the Hodzana and Kanuti Rivers are maturely eroded and are characterized by extensive alluvial gravel deposits in broad, terraced valleys with meandering streams that drain rounded hills. Outcrops are scarce. A generally treeless mat of vegetation covers all but the steepest terrain. The region is reported by Pewe (20) to be underlain by discontinuous permafrost. Alluvial deposits at these latitudes, however, are commonly frozen to depths of 100 to 400 ft. There is no evidence that glaciation has significantly af- fected the uplands area or has been a factor in the formation and preservation of placer deposits. Pleistocene ice ad- vances described by Hamilton (9) may have approached from the northwest, but the extent of glaciers or ice sheets is uncertain. They are not believed to have extended southeast of Sithylemenkat Lake. Some cirque and valley glaciation occurred in the Ray Mountains to the south of the study area, but studies by Yeend (24) indicate that the glaciers did not extend beyond the foothills. Climate in the study area is arctic continental. The ef- fective season for geologioc investigations extends from mid-May through late September. ^ 25 50 Scale, miles I'Qhway I Y//\ P'utons investigated during this study I I | Bonanza pluton \7jA Coal Creek P |uton 1 2 | Jim Riv er pluton \/ 7 /\ Fort Hamlin Hills pluton | 3 J Hodzana pluton J/p/J R ay River pluton I 4 | Kanuti pluton YM sitn y |emenka1 P'uton [///I Hot Springs pluton | 10 | Ray Mountains batholith. FIGURE 1.— Location of study area and granitic plutons in central Alaska. PREVIOUS WORK In 1963, a Bureau of Mines field crew observed an oc- currence of topaz, lithium, and radioactive yttrofluorite a short distance south of the study area. These minerals are frequently associated with lode tin deposits. The first known mention of tin in the area was in an Alaska Department of Natural Resources report published in 1969, in which Her- reid (10) reported that 10 granite samples from the Sithylemenkat pluton contained a mean of 32 ppm Sn, which is several times the normal trace-element background of tin in granitic rocks. In a 1970 USGS report, Patton and Miller (1 7) reported anomalous tin values in stream sediment (up to 300 ppm Sn) and in two geochemical rock samples (20 and 70 ppm Sn) from the Sithylemenkat pluton area; they recommended further investigation for lode and placer tin deposits. In 1973, the USGS released reconnaissance-scale (1:250,000) geologic maps and results of geochemical sam- pling in the Bettles and Southern Wiseman Quadrangles by Patton and Miller (18-19). Also in 1973, the USGS published the results of an aeromagnetic survey of the eastern Bettles Quadrangle (23). In 1978 and 1979, the Bureau collected 514 heavy-mineral panned concentrates (2) and found anom- alous tin values in and southwest of the Sithylemenkat pluton area, near the westernmost part of the Hot Springs pluton, and northwest of the Fort Hamlin Hills pluton. GENERAL GEOLOGY The Kanuti and Hodzana Rivers uplands are underlain by crystalline rocks, including pelitic schists, quartzites, and phyllites of probable Paleozoic age (18). These rocks are in- truded by five principal composite plutons: the Sithylemenkat, Ray River, Fort Hamlin Hills, Coal Creek, and Hot Springs plutons. All are composed primarily of biotite granite and biotite quartz monzonite, with minor quartz diorite and rhyolite porphyry. A Cretaceous age is indicated for the plutons on the basis of available potassium-argon age determinations. Biotite from the Kanuti pluton immediately north of the study area (fig. 1) has been dated at 90.6 ±6 million yr (6). Biotite from the Hodzana pluton, located approximately 30 miles north of the study area, has been dated at 101 ±5 million yr (5). An age of 106 ± 3 million yr has been deter- mined for biotite from the Sithylemenkat pluton (18). Radiometric ages are not available for the younger rhyolite porphyry that locally intrudes the granitic plutons. PLACER INVESTIGATIONS SAMPLING METHODS Alluvial samples were shoveled from stream bars and cutbanks; cutbanks were preferentially sampled whenever possible. After they were measured and screened, the samples were sluiced with a regulated water flow and fur- ther reduced by panning. To compensate for the natural swell of loose, excavated material, the measured sample volumes were multipled by 0.80. Extensive tundra cover, flood-washed coarse sand, and a lack of cutbank gravel exposures are characteristic of the study area. In some places, the only gravel exposures were under standing or flowing water. Consequently, some of the samples were collected with a floating gasoline-powered suction dredge with a 5-in-diam intake. This sampling method was chosen because the equipment is portable and is capable of processing a large volume of gravel from below the water. Dredge sample volumes were estimated by measuring the resultant cone-shaped excavation. Suction dredge recovery efficiency can only be qualitatively as- sessed; an unknown amount of concentrate probably was lost owing to the turbulent flow of unsized material over the sluice. Where this method was used, the tin recovery results are considered to be conservative. The heavy-mineral samples were further prepared for analyses by heavy liquid and magnetic separation. Bromoform (2.85 specific gravity) was used to float the light-mineral fractions. The heavy fraction was then separated into magnetic and nonmagnetic fractions. Both the magnetic and nonmagnetic fractions were weighed, and the nonmagnetic fractions were analyzed for tin, tantalum, columbium (also called niobium), cerium, thorium, and tungsten by energy-dispersive X-ray fluorescence spec- trometry. SITHYLEMENKAT PLUTON AREA The initial reconnaissances by the Bureau in 1978 and 1979 (2) indicated that the tin minerals are concentrated in alluvial gravels in the upper forks of the Kanuti Kiloitna River. Subsequent work has shown that placer samples (figs. 2-4) taken near the surface contain up to 0.4 lb/yd 3 Sn and lesser amounts of tantalum, columbium, tungsten, and rare-earth elements (tables 1 and 2). Based on the sampling results, the grade of placer gravels is expected to increase with depth. A higher grade at depth is indicated at sample location 5 (samples 5a-5b), where gravel from 0- to 2-ft depth contained 0.025 lb/yd 3 Sn, whereas gravel from 2- to 3-ft depth contained 0.076 lb/yd 3 Sn. A similar relationship was observed at sample location 2. (See samples 2a-2b in table 1.) The heavy-mineral content of surface samples varied markedly among closely spaced samples. Differences ap- peared to be related to the degree of washing during periodic floods. Generally, samples collected from com- pacted silt and clay-bound gravel in cutbanks and stream beds contained more tin. Gravel bars composed of fine, very loose, flood-deposited gravel with little silt and clay binder typically contained less heavy-mineral material. For exam- ple, at sample location 16, loose gravel on the right limit of the stream contained only 0.006 lb/yd 3 Sn, whereas silty gravel from the opposite cutbank contained 0.101 lb/yd 3 Sn. A sample of the intervening stream bed with more silt and clay contained 0.201 lb/yd 3 Sn. The principal tin-bearing drainage in the Sithylemenkat pluton area (fig. 2) is the east fork of the Kanuti Kilolitna River. This 10-mile-long tributary drains approximately one-third of the known areal extent of the Sithylemenkat pluton. Extensive alluvial deposits have accumulated along FIGURE 2.— Location of concentrated placer samples. FIGURE 3.— Detail of sample locations on east fork of Kanuti Kilolitna River. FIGURE 4.— Steam profile of east fork of Kanuti Kilolitna River. Table 1.— Tin analyses, weights, and volumes of placer concentrate samples (Samples are located by number In figures 2-4.) Sampling method and remarks Shoveled from active channel, concen- trated in 8- by 30-in portable sluicebox. Suction dredge sample from ac" Suction dredge sample from caisson be- tween 5- to 7-ft depth in gravel at same location as 2a. Suction dredge sample from active chan- nel along river. Suction dredge sample on active gravel bar with many medium-size boulders. Suction dredge sample from gravel bar along Kanuti Kilolitna River; cobbly gravel with boulders to 12-in diam; contains well- sorted gravel-silt fraction; cassiterite nug- gets noted. Shoveled from opposite side of gravel bar where 4a collected; screened and proc- essed through 12- by 36-in sluicebox. Shoveled from 5-ft-deep pit in dry stream deposited by river flooding. Sample pro- cessed in 12- by 36-in sluicebox. Suction dredge sample from depth of to 2 ft in active channel of Kanuti Kilolitna River. Suction dredge sample from depth of 2 to 3 ft in hole excavated for 5a. Shoveled from active channel and concen- trated in 8- by 30-in portable sluicebox. Shoveled from channel center; concen- trated by hand panning. Suction dredge sample from main channel; cobbles in creek to 14-in diam; most coarse posed granite sand. Shoveled from creek bank, approximately 4 ft below tundra level; processed in 12- by 36-in sluicebox. Located on left limit stream bank; sample shoveled from gravels immediately under 3 ft of muck and tundra; processed in 12- by 36-in sluicebox. nit alluvial in channel; concentrated in 12- by 36-in sluicebox. 222.62 73.11 Do. Do. Shoveled from active flood-washed gravel bar near right limit bedrock bank; concen- trated in 12- by 36-in sluicebox. Shoveled from active gravel bar in main channel; concentrated In 12- by 36-in sluicebox. Suction dredge sample from streambed of the active channel. Shoveled from base of left limit cutbank, approximately 7 ft below tundra level; con- centrated In 12- by 36-in sluicebox; gravel contains higher silt fraction than observed elsewhere. Shoveled from upper alluvial bench approxi- mately 150 ft from stream; sample was dry, friable, and composed mostly of silt and See explanatory notes at end of table. Table 1.— Tin analyses, weights, and volumes of placer concentrate samples— Continued Volume, fi- Concentrate, g Sn, Sn in original Orig- Minus Nonmag- Mag- Sampling method and remarks 5 in 0.25 in vol, lb/yd 3 18 NA 0.77 0.46 1.56 0.01 8.5 '.010 Shoveled from channel center; concen- trated by hand panning. 19 .93 .46 .62 .46 9.33 39.4 '.353 Do. 21 NA .93 .46 17.13 .81 33.7 '.369 Do. 22a 2 5.0 3.64 1.40 47.60 .06 24.5 .139 Located on right limit of stream; sample shoveled and sluiced from bank approx- imately 4 ft below tundra level; gravel somewhat iron stained. 22b ! 59.5 NA NA 478.80 10.40 39.9 .191 Suction dredge sample from midchannel at 22a. Located on left limit, occasional boulders 22c 2 7.0 4.71 1.40 69.57 .10 ( 3 ) < 3 ) up to 4-ft diam; samples shoveled and sluiced from bank approximately 6 ft below 23 NA 5.5 NA 102.31 .29 36.1 '.399 Shoveled from active channel; concen- trated in 8- by 30- in sluicebox. 24 NA 3.04 9.41 .04 41.9 '.077 Do. (4) NA 5.5 NA 58.51 7.48 1 '.001 Sample shoveled from granitic terrane as a check on regional background Sn concen- trations; sluiced in 8- by 30-in sluicebox. y method did not permit accurate m >t owing to computer failure. n accompanying maps; sample from approximately 4.7 miles east of Dalton Highway in T 19 N, F NOTE.— Analyses by semiquantitative X-ray fluorescence spectrometry by the Bureau's Juneau (AK) laboratory. ement of in-place volume. /, section 13. 'Not shown on accompanying maps; sample from approximately 4.7 miles east of Dalton Highway in T 19 N, R its lower course. Cassiterite, the only tin mineral identified in the area, is a major component in heavy-mineral fractions from the Kanuti Kilolitna River (based on identification by x-ray diffraction and petrographic methods, using a random suite of samples -samples 1, 6, 7, and 23-24, as listed in table 1). Cassiterite was found as nuggets ranging in size up to 0.75 in across and varying in color from mostly black to, less commonly, gray and brown. Larger nuggets that may have been present would have been lost during screening or sluicing of the sampled material. However, the cassiterite grains generally did not exceed the size of course sand. Nug- get loss, if it occurred at all, probably was not significant. The concentrated heavy-mineral samples also common- ly contained fragments of greisen with finely disseminated sulfide minerals and cassiterite. Although some pieces of greisen contained minor magnetite, the greisen fragments were found in the nonmagnetic fraction. Because of its lower specific gravity, most greisen material generally was not recovered in the heavy-mineral concentrates. Placer concentrates examined petrographically and by X-ray dif- fraction (samples 1, 6-7, and 23-24) also contained variable amounts of wolframite, pyrite, ilmenite, hematite, garnet, monazite(?), and lesser unidentified heavy minerals. The wolframite mineral in sample 23 was identified as ferberite, and traces of scheelite were observed by ultraviolet fluorescence in samples 7, 23, and 24. Generally, magnetite grains are sparse in the Sithylemenkat area (table 1) and comprise less than 0.5 wt pet of most concentrates. All of the concentrates in table 1 were visually examined; no gold and only trace amounts of scheelite were observed. Four gradient segments of the east fork of the Kanuti Kilolitna River were sampled. (See profile A-B-C in figure 4.) The first segment, shown in figure 5, is the lower end of a broad alluvial outwash deposit. The outwash deposit is ap- proximately 0.25 mile wide and is bordered by terraced alluvial deposits. This lower segment contains the largest alluvial gravel deposits within the east fork valley and yielded some of the higher tin values (up to 0.404 lb/yd 3 Sn, from sample 7). The second gradient segment is a generally well-rounded valley with local bedrock constrictions in the lower portion and gravel terraces along the midsection to upper section. Samples from the lower portion (of the sec- ond segment) also contained significant tin values (samples 13-14). The third segment is a more steeply inclined canyon with numerous boulders and little sediment accumulation. Although tin was found in samples (samples 15 and 16a-16d), the lack of alluvial gravel deposits precludes potential for placer reserves. Lastly, the fourth, upper- valley segment is well-rounded and terraced, but is con- siderably narrower than the lower valley. Samples collected in this segment generally contained 0.1 to 0.4 lb/yd 3 Sn. The difference in tin content between the two upper forks (0.077 lb/yd 3 Sn in sample 24 and 0.399 lb/yd 3 Sn in sample 23) is coincident with the occurrence of greisen veins within the area drained by the southern fork (sample 23). Two placer samples, 2a and 2b (fig. 2), were collected from a single location on the upper Ray River immediately downstream from the southeasterly margin of the Sithylemenkat pluton. Only minor concentrations of tin (0.008 to 0.015 lb/yd 3 Sn) were found; however, the only gravels available for sampling were well sorted and lacked a fine sediment fraction. Consequently, the relatively low tin values may or may not indicate a lack of significant placer tin at depth in the alluvium. NORTHERN RAY MOUNTAINS AREA The Ray Mountains, another possible source of tin located south of the study area, are underlain by a deeply eroded granitic batholith of the same name (figure 1, loca- tion 10). North-flowing streams, such as the south fork of the Kanuti Kilolitna River, have reworked and deposited alluvial and glaciofluvial granitic sediments beyond the foothills of the Ray Mountains and within the study area (fig. 1). Sample sites 3 and 4 (fig. 2) were selected because they are areas of slightly reduced stream gradient with a corresponding widening alluvial plain. To the south, the river is swift and turbulent and generally occupies a single channel, but braided sections occur locally where the gra- dient abruptly decreases. Beyond the foothills (north of sam- ple location 3 in figure 2), the gradient decreases, and the river becomes a meandering stream. Although the tin content in the gravels of the south fork of the Kanuti Kilolitna River was lower (not exceeding 0.08 lb/yd 3 Sn) than that encountered on the river's east fork, the south fork gravels appeared to be considerably deeper and occupied a much wider river plain (varying from 0.25 to 1 mile in width). Consequently, surface gravels are subject to reworking by migrating channels, and dilution occurs from other gravel sources. The heavy-mineral fraction would be expected to be more highly concentrated at some depth below the active streambed, and surface samples would only contain relatively low tin concentrations. For this reason, drilling or trenching is needed to further locate and assess cassiterite concentrations in the northern Ray Mountains INVESTIGATION OF GRANITIC PLUTONS SAMPLING METHODS Granitic plutons within the study area (fig. 1) were in- vestigated as potential hosts for tin deposits. Cassiterite- bearing float was found in the Sithylemenkat pluton area, and subsequent investigations identified several rubble ex- posures of tin greisen. The chemistry of the other plutons was compared with the chemistry of the Sithylemenkat pluton and well-known Australian tin granites to determine if the studied plutons are favorable for tin deposits. Rock samples were collected for petrographic examina- tion and major-oxide and trace-element analyses (Appendix A). Major-oxide samples were chipped from relatively unweathered, frost-riven boulders over areas of at least 1,000 ft 2 . Samples collected for trace-element analyses con- sisted of random chips collected within a few feet of the sample station (unless otherwise noted in Appendix A). The descriptions of the samples listed in Appendix A were taken from field notes that were supplemented in some cases by thin-section examination. Sample analyses were provided by the U.S. Department of Energy (DOE) under an agreement with the Bureau of Mines. Analyses for beryllium and lithium were performed by emission spectrography. X-ray fluorescence was used for arsenic, silver, bismuth, cadmium, copper, columbium, nickel, lead, tin, tungsten, and zirconium analyses. Neutron activation with a short time delay before analysis was used for barium, chlorine, manganese, strontium, titanium, and vandadium analyses; neutron activation with a long time delay before analysis was used in analyses for gold, cerium, cobalt, rubidium, antimony, tantalum, thorium, and zinc. The procedures used and complete analytical results are presented in open file reports by DOE (2, 21). In these DOE reports, samples are identified by their field numbers; however, in this report, a simplified numbering system is used to identify the same samples. For this reason, a sample identification key (appendix B) is included to show the cor- respondence of the sample numbers used here with those used in the DOE reports (the field numbers). SITHYLEMENKAT PLUTON Geology The Sithylemenkat pluton is a 200-mi 2 composite batholith located west of the Dalton Highway (figs. 1 and 6). Geologic mapping confined to the northern half of the pluton identified four texturally different granite phases (fig. 6): porphyritic granite, granite porphyry, coarse- grained granite, and graphic granite. Age relations between the four phases are unclear because of a lack of outcrop. Mineralization Tin-bearing rocks were found in two areas in the Sithylemenkat pluton (MZ on figure 6), and mineralized float commonly occurs in the upper tributaries of the east fork of the Kanuti Kilolitna River. Chlorite-bearing and locally magnetite-bearing greisen are intermixed with aplite, frost-riven graphic granite (gg), and coarse-grained granite (eg) rubble. The north end of the western MZ area overlies an intersection of linear structural features (fig. 7) where the extent of greisen and otherwise altered rock could not be determined due to a lack of bedrock exposure. A north-trending greisen zone was traced for 1,200 ft along the southern end of the area. At one bedrock exposure, the zone was between 10 and 15 ft wide. Mineralized rock samples show variable effects of greisenization, with tourmaline and magnetite sometimes present. Fine-grained sericite- and quartz-rich veins and altered dikes contain abundant secondary chlorite, and locally contain up to several percent sulfide minerals, in- cluding pyrite, arsenopyrite, galena, and molybdenite. Greisen ruble is recognized in the field by its dark green to reddish-brown color, well-rounded weathered surface, and high specific gravity. In thin section, the greisen showed a relict porphyritic texture in which feldspar phenocrysts were replaced by a felty intergrowth of very fine-grained quartz and sericite. This material was further replaced by a felty aggregate of chlorite and clay minerals in more pervasively altered specimens. Anhedral bladed cassiterite grains, less than 1 mm long and intimately intergrown with a felty aggregate of fine-grained chlorite, quartz, and white mica, were iden- tified petrographically in creek float of chloritic greisen col- lected downstream from sample location 71 (fig. 8). Greisen samples from the areas labeled MZ in figure 6 contained from 25 to 2,300 ppm Sn (table A-l). Greisen samples from these areas also contained, up to in parts per million, 5,126 As, 326 Bi, 253 Cs, 1,808 Cu, 15,340 Mn, 34,027 Pb, 1,156 Rb, 135 W, and 4,044 Zn (table A-l). Greisen from these areas ranges from light-colored to dark green. The highest tin concentrations were detected in the dark green chloritic greisen (sample 71d, figure 8 and table A-l). The extent of the tin-rich greisen at sample location 71 was not determined, but it appeared to be concentrated in a 300-ft-long, 100-ft-wide area along the east side of the south-striking ridge shown in figures 6 through 8. RAY RIVER PLUTON Geology The Ray River pluton is a poorly exposed intrusive body that occupies a 35-mi 2 area west of the Dalton Highway (fig. 1). It is composed mainly of fine- to medium-grained equigranular granite and quartz monzonite, with subor- dinate amounts of nonequigranular to porphyritic granite. These rocks are composed of 30 to 50 pet orthoclase, 20 to 40 pet oligoclase, 20 to 25 pet quartz, and less than 5 pet biotite. Muscovite and tourmaline were also observed in rocks from the center of the area, and feldspar is commonly altered to sericite and clay minerals. Aeromagnetic data (23) indicate that the Sithylemenkat and Ray River plutons may be connected at shallow depths. Mineralization No tin mineralization was observed in the Ray River pluton, and geochemical rock samples were not anomalous. Rock sample locations are shown in figure 8, and sample analyses and descriptions are presented in table A-l. HOT SPRINGS PLUTON Geology The Hot Springs pluton (fig. 1) is a 100-mi 2 east- trending granitic complex composed mostly of coarse- grained porphyritic and seriate biotite granite and biotite quartz monzonite with minor hornblende. The pluton is locally intruded by younger dikes and stocks of rhyolite por- phyry. In thin section, textures in the granitic rocks of the Hot Springs pluton vary from hypidomorphic to granular. Graphic and micrographic intergrowths among quartz and feldspar grains are common in the groundmass of these granites. Perthitic orthoclase, albite-twinned plagioclase, and biotite phenocrysts are set in a groundmass of anhedral quartz and two feldspars, with interstitial and euhedral biotite. Biotite phenocrysts sometimes contain metamict zir- con inclusions. Accessory minerals include tourmaline, zir- con, apatitie, magnetite, and pyrite. Dikes and stocks in the Hot Springs pluton area are composed of porphyritic rhyolite and granular, leucocratic granite. These rocks are variably altered and range in color from bleached white to iron-stained red. Mineralization Above-average concentrations of lithium, copper, arsenic, tin, antimony, lead, and uranium were detected in samples of altered rhyolite porphyry, biotite granite, and leucocratic granite that occur as rubble on a narrow, steep- sided ridge in the Hot Springs pluton. Metazeunerite [Cu(U0 2 )2(As0 4 ) 2 -8H 2 0] was identified by X-ray diffraction of sample 149, a gray-green-weathering, altered rhyolite porphyry that contained over 1,000 ppm U, 341 ppm Cu, 2,616 ppm Pb, and 218 ppm Sn. Similar pieces of mineral- ized float were sparsely distributed along the ridge. The ex- tent of the mineralization is masked by soil and talus, but may account for tin anomalies in panned concentrates of alluvial gravel found nearby (2). Figures 9 and 10 show the sample locations and geology along the ridge and the loca- tions of other samples from the Hot Springs pluton. Results of the geochemical analyses are listed in table A-2. map of Sithylemenkat pluton. FIGURE 6--Geoli FIGURE 7.— Aerial views of structural intersection where a chlorite-rich tin-bearing greisen occurs (sample locations 72 and 73, as shown in figure 8), looking to the west (left) and north (right). FIGURE 8.— Rock sample location map for Sithylemenkat and Ray River plutons. FIGURE 9.— Sample location map for Hot Springs pluton. FIGURE 10.— Sample location and geologic map of metazeunerite occurrence in Hot Springs pluton. LEGEND • 180 Sample location and number Note : See appendix A for qeochemical analyse Contour interval 1000 ft FIGURE 11.— Rock sample location map for Coal Creek and Fort Hamlin Hills plutons. FORT HAMLIN HILLS PLUTON Geology The Fort Hamlin Hills pluton (fig. 1) underlies an 80-mi 2 area between the Dalton Highway and the Yukon Flats. Most of the pluton is covered by unconsolidated surficial deposits. The Bureau's investigation was confined to the southern portion of the pluton, where the contact with horn- felsed Paleozoic schists and quartzites is exposed. The ex- amined area is composed mostly of medium- to coarse- grained, locally porphyritic biotite granite and quartz mon- zonite that are locally intruded by hydrothermally altered leucocratic, felsic dikes that contain accessory pyrite and tourmaline. Mineralization Sample 181 was collected from a tourmaline- and pyrite- bearing altered 5- to 8-ft-wide felsic dike that cuts the biotite granite. The dike was variably stained brick-red and green, and exposed for 50 ft along a north-trending strike. An altered zone extends into the granite for at least several feet. Secondary minerals in the dike and the biotite granite host rock include minor chlorite, sericite, tourmaline, hematite, and pyrite. Sample 181 contained 308 ppm Sn and 1,102 ppm Rb, with traces of tantalum (29 ppm) and tungsten (16 ppm). The sample locations are shown in figure 11, and the analytical results are listed in table A-3. Kanutl and Hodzana River uplands, 1 (Samples are located by number in figures 8-11.; 1 ". . . . 46 60 110 161b 170c 166 137a 150 129 184b MAJOR-OXIDE ANALYSES 75.80 76.20 75.40 77.60 75.10 71.90 70.60 78.00 75.10 74.80 .20 .26 .12 .38 .45 .35 .15 13.40 12.40 13.10 12.60 12.90 14.20 14.00 12.30 12.80 13.00 .65 .86 .26 .24 .33 .73 1.40 .40 1.10 .78 .83 1.10 1.40 .35 .57 1.80 1.70 .13 1.20 1.00 .03 .04 .04 .02 .02 .05 .05 .04 .02 .15 .22 .31 .04 .09 .56 .81 .07 .37 15 .59 .70 .89 .53 .69 1.70 1.60 .04 .89 .63 3.20 2.90 2.80 3.70 3.40 3.40 3.20 .38 3.10 3.00 5.00 5.30 5.20 3.90 5.10 5.20 5.10 4.90 5.00 5.30 .02 .02 .02 .02 .02 .10 .09 .02 .08 .02 99.83 99.97 98.68 99.12 98.36 100.02 99.00 96.35 100.03 98.85 Orthoclase Albite NORMATIVE MINERALOGY Corundum . . . Hypersthene . Magnetite . . . 34.45 35.25 34.50 37.82 32.58 30.13 32.09 31.35 23.55 31.03 29.31 26.29 25.66 33.96 31.44 \7M 26.78 56.96 35.34 33.83 30.73 31.12 31.31 29.55 32.34 28.77 29.67 3.69 26.23 27.82 7.78 7.59 .21 3.89 3.23 .13 .59 7.44 .86 1.33 3.56 2.49 .21 1.71 .68 1.06 .92 .00 1.59 .54 .72 .65 .10 .66 .22 .23 .19 .19 k technique by Skyline Laboratories, Wheatridge, CO. Coarse-grained porphyritic i nh micrographic 110 Coarse-grained porphyr i . , 'lemenkat pluton. 161b Coarse-grained biotite granite from Coal Creek pluton. 170 Medium-grained biotite granite from Coal Creek pluton. 166 Coarse-grained biotite granite from Coal Creek pluton. 137a Porphyritic biotite granite with medium- to coarse-grained groundmass Rhyolite porp- i -! unngs pluton. e from Sithylemenkat pluton. 129 Seriate to porphyritic biotite granite from H 184b Coarse-grained biotite granite from Fort Hamlin COAL CREEK PLUTON Geology The 75-mi 2 Coal Creek pluton crops out east of the Dalton Highway and north of the Yukon Flats (fig. 11). This body is very similar in composition to the Sithylemenkat pluton. Porphyritic and seriate biotite granite and quartz monzonite are the most common rock types. Granular tex- tures are observed more rarely. Locally, veins and radial ag- gregates of tourmaline were observed. Siliceous fine- grained felsic rocks with tourmaline crystals up to 4 in long were commonly seen in float at the northeastern margin of the pluton. In thin section, the porphyritic rocks show micrographic and cataclastic textures. Mineralization No mineralization was observed during the Bureau's in- vestigation of the Coal Creek pluton. However, a previously reported stream-sediment sample collected from a gulch containing abundant vein quartz on the easternmost extent of the pluton contained 185 ppm U (1). Sample locations for the Coal Creek pluton are shown in figure 11, and the analytical results are listed in table A-3. MAJOR-OXIDE ANALYSES Major-oxide analyses on 10 chip samples (listed in table 3 and located in figures 8-9 and 11) indicate that plutons in the Kanuti and Hodzana Rivers uplands are similar in com- position to tin granites found in New South Wales, Australia. Juniper and Kleeman concluded that "tin- mineralizing granites" can be characterized on the basis of their aluminum, calcium, iron, magnesium, potassium, silica, and sodium contents (U). For comparison, fields for tin-mineralizing granites in New South Wales, as determin- ed by Juniper and Kleeman (U), are shown in ternary diagrams in figure 12. The ternary diagrams are based on normalized compositions in the following systems: CaO + MgO + FeO : Si0 2 : Na 2 + K 2 + A1 2 3 (fig. 12A) Na + K : Fe : Mg (fig. 12B) K : NA : Ca (fig. 12Q Plots of samples from the Sithylemenkat, Coal Creek, Hot Springs, and Fort Hamlin plutons generally fell within the fields for tin-mineralizing granites. No samples were col- lected from the Ray River pluton for major-oxide analyses. A sample of rhyolite porphyry intrudes the plots near the tin-mineralizing fields in figures 12A and 12B, but is well outside the tin-mineralizing field in figure 12C. Samples from the Sithylemenkat, Coal Creek, and Fort Hamlin Hills plutons consistently plotted within, or very near, the fields for tin-mineralizing granites. TRACE-ELEMENT ANALYSES Trace-element analyses on 146 rock samples from plutons in the Kanuti and Hodzana Rivers uplands (appen- dix A) indicate that the plutons are chemically similar to tin granites elsewhere in the world. All are enriched in lithium, copper, zinc, arsenic, rubidium, tin, cesium, lead, tungsten, bismuth, and thorium. Locally elevated levels of columbium and tantalum were also detected. Only the Ray River pluton samples were enriched in beryllium, but all were depleted in barium. All but the Coal Creek pluton samples were depleted in manganese, and all but the Fort Hamlin Hills samples were depleted in zirconium. These enrichment- depletion findings, as compared to average granites, are common among tin granites described by various authors (3-4, 7-8, 11-13, 16, 22). Analyses of unaltered, nonmineralized samples from the plutons are summarized and compared to those of average granites in table 4. Mineralized or altered samples (which are not included in table 4). are noted in appendix A (foot- note 2 in each of the appendix tables). In table 4, the elements are presented in order of increasing atomic number, and the number of analyses (n) for each element varies due to matrix interferences during analysis. Coal Creek pli FIGURE 12.— Comparison of Kanuti and Hodzana Rivers uplands plutons with Australian mineralizing granites." Sithylemenkat Fort Hamlin Hill! 66.36 24.75 271.34 143.77 10.04 14.09 261.48 22.58 146 'Analyses by Los Alamos (NM) Scientific Laboratories. DISCUSSION AND RECOMMENDATIONS TIN PLACER DEVELOPMENT POTENTIAL The data in tables 1 and 2 indicate that placer tin, tungsten, tantalum, and columbium minerals occur in deposits of unknown grade at several localities in the Kanuti Kilolitna River drainage. Sampling was limited to shallow pits. No samples were taken from near bedrock; therefore, the grade and extent of the underlying gravels could not be assessed. However, it is likely that the amount of concen- trate present per cubic yard of gravel increases with depth, particularly in the coarse granitic sands and gravels. Further work should include sampling of the subsurface gravels by backhoe trenching supplemented by drilling where necessary. It is suggested that the areas denoted on figure 13 (by the numbers 1 through 6) and listed below be sampled for placer concentrations of cassiterite and associated economic minerals. 1. The westerly flowing streams, both north and south of the Kanuti Kilotina east fork valley, may contain relative- ly small but possibly high-grade stream placers. These streams drain areas where tin occurrences were found. 2. The semiclosed basin drained by the south fork of the Kanuti Kilolitna contains complex alluvial and glaciofluvial deposits derived from the Ray Mountains batholith further to the south. The tin content of five placer samples downstream from Kilo Hot Springs (samples locations 3-4, figure 2) and heavy-mineral panned concentrates (2) from other tributaries suggest that cassiterite concentrations are present. The placer samples collected from flood-plain gravels contained 0.02 to 0.08 lb/yd 4 Sn. Exploration should assess the extensive active and ancient alluvial channels leading into and within the basin. Placer tin deposits, if pre- sent, may be large, but are likely of lower grade than the smaller stream placers. 3. Placer deposits may be present in the active alluvium and alluvial terraces of the main valley of the Kanuti Kilolit- na River for 3 to 4 miles downstream of the basin mentioned above. Two placer samples collected from flood-plain gravels contained 0.03 to 0.08 lb/yd 3 Sn (sample locations 5a-5b, figure 3). A sample from further upstream (location 6, figure 3) contained approximately 0.02 lb/yd 3 Sn. 4. Residual or eluvial placer deposits may occur in the immediate area of lode mineralization south of hill 3536 (fig. 36). This area maybe more extensive than shown in figure 13. 5. Channel deposits in glaciofluvial outwash along the upper south fork of the Kanuti Kilolitna, which are derived Further field mapping and sampling is required to determine the significance of the tin anomalies in the western Hot Springs and Fort Hamlin Hills plutons. The northern poorly exposed portion of the Fort Hamlin Hills pluton is particularly recommended for further examination due to the presence of tin in panned concentrates, from the Ray Mountains, may contain significant placer tin deposits. The Ray Mountains batholith, south of the study area, is a deeply eroded granitic body; and although no lode tin mineralization is known, tin was previously found in pan- ned concentrate samples of alluvium derived from the batholith (2). 6. West- and north-flowing streams, particularly the Ray River, which drains the Sithylemenkat pluton to the east, should be further evaluated for placer tin deposits, despite the relatively low values found in placer samples at location 2 (fig. 2). Panned concentrates from the upper Ray River contained anomalous tin (2). 7. Areas of anomalous alluvial tin (2) in the north- western vicinity of the Fort Hamlin Hills and western Hot Springs plutons (not shown in figure 13 - see fgure 1) should be further evaluated for tin mineralization. Logistic con- straints prevented sampling in these areas during this in- vestigation. LODE TIN DEVELOPMENT POTENTIAL Major-oxide and trace-element analyses and tin occur- rences indicate that the plutons of the investigated area are chemically similar to other granitic intrusions that have given rise to tin mineralization. Tin mineralization in granites typified by their similar chemistries results from post magmatic processes involving the development of an alkali-rich volatile phase during crystallization (16). Tin greisen deposits are typically found in the upper, volatile- rich portions and cupolas of plutons. It is possible that such upper intrusive levels and associated tin deposits have been mostly or completely removed during subsequent erosion of the exposed plutons in the study area. The Sithylemenkat pluton, however, hosts several mineralized zones near the head of the east fork to the Kanuti Kilolitna River. This is evidence that at least some remaining deposits have escaped erosion. Trenching and further sampling near the mineralized zones in the Sithylemenkat pluton are needed to determine the nature and extent of mineralization. Additional detailed mapping is also needed to delineate the host phase of the tin occurrences. The distribution of placer tin indicates that the mineralized zones are, or were, more widespread than those found. Initially, magnetometer surveys may serve to better define the zones. CONCLUSIONS The east fork of the Kanuti Kilolitna River contains cassiterite with lesser amounts of tungsten, columbium, tan- talum, and rare-earth minerals in near-surface alluvial and bench gravels. These minerals were also found in the gravels of the south fork of the Kanuti Kilolitna near the foothills of the Ray Mountains. Placer samples collected from surface exposures commonly contained 0.02 to 0.14 lb/yd 3 Sn. It is likely that the concentration of heavy minerals increases with depth. The sample results suggest that tin and associated elements may occur as placer deposits in these and other streams draining the granitic plutons in the Kanuti and Hodzana Rivers uplands. A large semibasinal area in the Kanuti Kilolitna drainage that con- tains ancient and present alluvial channels appears to be particularly favorable for large placer tin deposits. Analyses of rock samples showed that the granitic FIGURE 13.— Areas of tin reserve potential suggested for further placer investigations. plutons studied resemble granitic bodies elsewhere in the: world that are known to contain valuable deposits of tin and J associated metals. Mineralized zones in the Sithylemenkat; pluton were identified in rubble and indicate that at least some lode tin deposits exist. However, the deeply eroded nature of the region suggests that larger tin-bearing cupola zones, if originally present, may now be eroded away. Estimating the potential value of lode and placer tin deposits in the uplands between the Ranuti and Hodzana Rivers and adjacent areas will require extensive surface and subsurface exploration. REFERENCES 1. Averett, W. R., and J. C. Barker. Report of Analyses from Mineral Resource Investigations in Central and Eastern Alaska. U.S. DOE Open File Rep. GJBX-178(81), 1981, 148 pp. 2. Barker, J. C. Reconnaissance of Tin and Tungsten in Heavy Mineral Panned Concentrates Along the Trans-Alaska Pipeline Corridor, North of Livengood, Interior Alaska. BuMines OFR 59-83, 1983, 24 pp. 3. Beus, A. A. Geochemical Criteria for Assessment of the Mineral Potential of Igneous Rock Series During Reconnaissance Exploration. CO Sch. Mines Q., v. 64, 1969, pp. 67-74. 4. Boissavy-Vinau, M., and G. Roger. The Ti0 2 /Ta Ratio as an In- dicator of the Degree of Differentiation of Tin Granites. Miner. Deposita, v. 15, 1980, pp. 231-236. 5. Brosge, W. P., H. N. Reiser, and W. E. Yeend. Reconnaissance Geologic Map of the Beaver Quadrangle, Alaska. U.S. Geol. Surv. Misc. Field Stud. Map MF-525, 1973; 1 sheet; scale 1:250,000. 6. Clautice, K. H. Geological Sampling and Magnetic Surveys of a Tungsten Occurrence, Bonanza Creek Area, Hodzana Highlands, Alaska. BuMines OFR 80-83, 1983, 80 pp. 7. Flinter, B. H. Tin in Acid Granitoids: A Search for a Geochemical Scheme of Mineral Exploration. Paper in Geochemical Exploration. Can. Inst. Min. and Metall., Spec. v. 11, 1971, pp. 8. Flinter, B. H., W. R. Hesp, and D. Rigby. Selected Geochemical, Mineralogical and Petrological Features of Granitoids of the New England Complex, Australia, and Their Relation to Sn, W, Mo and Cu Mineralization. Econ. Geol., v. 67, 1972, pp. 1241-1262. 9. Hamilton, T. D. Glacial Geology of the Lower Alatna Valley, Brooks Range, Alaska. Geol. Soc. America, Spec. Paper 123, 1969, 223 pp. 10. Herreid, G. Geology and Geochemistry, Sithylemenkat Lake Area, Bettles Quadrangle, Alaska. AK Dep. Nat. Resour., Geol. Rep. 35, 1969, pp. 1-3. 11. Hesp, W. R. Correlations Between the Tin Content of Granitic Rocks and Their Chemical and Mineralogical Composition. Paper in Geochemical Exploration. Can. Inst. Min. and Metall., Spec. V. 11, 1971, pp. 341-353. 12. Hesp, W. R., and D. Rigby. Some Geochemical Aspects of Tin Mineralization in the Tasman Geosyncline. Miner. Deposita, v. 9, 1974, pp. 49-60. 13. Hine, R., I. S. Williams, B. W. Chappel, and J. R. White. Con- trasts Between I- and S-type Granitoids of the Kosciusko Batholith. J. Geol. Soc. Aust., v. 25, 1978, pp. 219-234. 14. Juniper, D. N., and J. D. Kleeman. Geochemical Characteriza- tion of Some Tin Mineralizing Granites of New South Wales. J. Geochem. Explor., v. 11, 1978, pp. 321-333. 15. Levinson, A. A. Introduction to Exploration Geochemistry. Applied Publishing Ltd. (Maywood, IL), 1973, pp. 43-44. 16. Olade, M. A. Geochemical Characteristics of Tin-Bearing and Tin-Barren Granities of Northern Nigeria. Econ. Geol., v. 75, 1980, pp. 71-82. 17. Patton, W. W., Jr., and T. P. Miller. Preliminary Geologic In- vestigations in the Kanuti River Region, Alaska. Ch. in Contribu- tions to Economic Geology, 1969. U.S. Geol. Surv. Bull. 1312-J, 1970, pp. J1-J10. 18. Bedrock Geologic Map of Bettles and the Southern Part of Wiseman Quadrangles, Alaska. U.S. Geol. Surv. Misc. Field Stud. Map MF-492, 1973; 1 sheet; scale 1:250,000. 19 Analyses of Stream-Sediment Samples From the Bettles and the Southern Part of the Wiseman Quadrangles, Alaska. U.S. Geol. Surv. Open File Rep. 73-219, 1973, 52 pp. 20. Pewe, T. L. Quaternary Geology of Alaska. U.S. Geol. Surv. Prof. Paper 835, 1975, 145 pp. 21. Stablien, N. K. Report on the Mineral Resource Investiga- tions in Six Areas of Central and Northeastern Alaska. U.S. DOE Open File GJBX-33(80), 1980, 186 pp. 22. Tauson, L. V., and V. D. Kozlov. Distribution Functions and Ratios of Trace-Element Concentrations as Estimates of the Ore- bearing Potential of Granites. London Symp., v. 37-44, 1973, pp. 37-44. 23. U. S. Geological Survey. Aeromagnetic Survey, Eastern Part Bettles Quadrangle. Open File Map 73-305, 1973. 24. Yeend, W. E. Glaciation of the Ray Mountains, Central Alaska. Paper in Geologic Survey Research 1971, Chapter D. U.S. Geol. Surv. Prof. Paper 750-D, 1971, pp. D122-D126. .2 i £ |— >j | III °° Q £* I E l O OS 00«9 9 " "v° v - E *S I 9 9 991 9 1 I M| I J !!!!!! a ass i a t **g E | I M g 8 a =«S ! 5 in i n »|tf v "v 9*9 5 99 "99 9 9 s !!! I *9 gen a | | 2 5 a EH g ft a s a s S ft S 8 ! ■ ■ ro&g | | || | I | j II 3 §1323 35= I 5 a a v v !! i i » a I B | S 8 S a a naa aa ; . | » „» s «. 3 f 5 ? I * **» 35 5 5 3 < V VVV VV V 1 1 * »l p 9 8 2 I 3 525 23 3 = § a ■ m ?3 v ro " s § ? ? ^ e? ? ? « ^ 3 "S3 M ? » s s s ;gs as s | !•?«!«! « a i g ssi si a « I ? 5 s«s s? s i S Sfe S88 S8 8 R I £ s sfee ss c s * 1 $ 5$S «S 5 ? 2 8 £ § C 5 SSE fe$ 5 I ! f | 8 5 SSS 88 ft 8 g 5 II 5111 m 3 I i 13 | | 5 3 3| S 35 Is S 3 3 1 isss aas i 3 3 33 a a s 3 3? s 33 33 a 3 3 ? »«», p «. » . 5 ■.- » . . . .. . .. .0 . . - . §SS2 §ss sss^s s s 5 ? g 1 ; g ssi 3S s s s ^ 999- 999 9 9 9 19 5 * 9 9 9i 9 ~9 99 9 s 9 " vv'f v^v v v " |v ™ v v " N v " " VV V " v 8 88g HE 8 I 8 ~8 S B|B 1388888 3888 -m 333 2 3 5 13 § a s 3 25 3 ss ss S3 3 2 ^v^§ vSS I 3 v R| v 3 " I v" V vS Ti V 3 3 V 99°9 "» 9 9 9 ^ 9 ^is!»«;;;g 999" 9" 9 9 9 •? 9 9 9 9 99 9 §9 99 5 9 9 9 s^feg 5 ss e s § s§ a s 9 s sfe § ss gs s 2 f 9 !!f !!!!!! s ! i m !? ! 9UII1 « 1^1 Igs i s s p te s s 1 sb S ss ;s 3 s 1 1 5 59£ I ^ 5 9 -I III" S 52 5 9 99 9 9 99 " BE8g *9« M" 6 ^ 9 9 "5 5 5 9 9 58 8 «» 99 8 b 8 s s » s °55§ t°S • ; S5S 5 § ; 5 ss t ?5 2? g J t ; ? SS ? 8888 3§g § S 5 8S 8 | 8 £ S | S S| 56 g R g 8 S 88 B «« *!? ! ! ! 1! 9 ■! « R ■ » ■? B ■ ■■ ! ■ « I ; 555 K S 5 £S 8 § 5 g SB S ! iiiiB i 1 1 1 «i i j S 8 B aSU ft B | | S||| ii i! il I Si II APPENDIX B.— SAMPLE IDENTIFICATION KEY (Sample numbers used in this report related to field numbers used in DOE open file reports (1, 21)) Sample Sample KA 10838 RM11014 RM11015 RM 10073 RM 10074 RM 10066 RM 10067 RM 10068 RM11013 RM11012 KA10839 KA10837 RM11011 PB15145 PB10403 PB10405 PB10406 PB10404 PB16230 PB16228 PB16224 PB16216 PB16214 PB16215 PB16221 PB16211 PB16222 PB16218 PB16219 PB16220 PB15146 PB10411 PB10412 PB10410 KA10840 KA10841 PB12617 PB12618 PB15551 PB15550 PB11126 PB15549 PB15548 PB12620 PB11128 PB11127 PB10285 PB10286 PB10287 PB10288 PB10289 PT11129 PB10284 PB11155 PB11156 KA 9696 PB15878 PB11157 PB12657 PB10192 KA 9698 PB10243 PB12645 PB12646 PB12647 PB12648 PB12654 PB12649 PB15873 PB15874 PB15875 PB10311 PB10310 PB10419 PB12362 PB15869 PB15867 PB15868 PB10299 PB10300 PB10301 PB16179 PB12360 PB16180 PB12357 PB12373 PB16181 PB12374 PB12352 PB12355 71e PB12356 71f PB16182 72 PB12364 73a PB12366 73b PB16183 74 PB12623 75 PB10292 76 PB10291 77 PB10290 78 PB12659 79 PB12658 80a PB10420 80b PB10422 81a PB16041 81b PB16042 82 PB10425 83 PB10423 84 PB10307 85 PB10303 86 PB10304 87 PB15872 88 PB15870 89 PB12643 90 PB11154 91 PB11152 92 PB12633 93 PB12632 94 PB12631 95 PB12630 96 PB12635 97 PB12636 98 PB10188 99 PB10185 100 PB10186 101 PB10183 102 PB10187 103 PB12638 104 PB11150 105a .... PB12969 105b .... PB12970 106 PB12968 107 PB11141 108 PB11142 109 PB11143 110 PB15877 PB12994 PB12995 PB12996 PB12997 PB11147 PB15771 PB15772 PB15635 PB15697 PB12691 PB12690 PB12689 PB12939 PB12938 PB12937 PB15861 PB15857 PB15856 PB15855 PB15854 PB15853 PB16047 PB16046 PB16156 PB16157 PB12934 PB12935 PB12936 PB236 PB249 PB12697 PB12696 PB12693 PB 15595 PB 15632 PB 15695 PB15631 KA 9946 KA11263 KA11264 PB15690 PB15691 PB15693 PB15633 PB15628 PB15774 PB15775 PB15776 KA 9961 PB11131 PB11132 PB11133 PB12925 PB11134 PB15799 PB15802 PB 15589 PBv15587 PBV15591 PBV15590 PBV15592 PBV15593 PBv15576 PBV15561 PBv15562 PBV15559 PBv15556 PBV15563 PBV15555 PBV15564 PBv15565 PBV15568 PBv15521 PBV15522 PBV15567 PBv15662 71S7 480 I- & * V * ^ ' ^0« ^ v !^HIa- T.I -^Pw! ll ;W®M. .A-* ^^iii^» <^>Tn, "WWW,* *** ♦. '.■ ?.• J"»+ VW/" V'« : V". .\' w /. ...V-"' > - <** r oK * e ■ jy <* *' .. ,o\c^!^ ^ o v" .£ *U* -7 €-' S h * ^«v HI- ^ 'W °'1«^ ** "V^-"/ I ° " ° » . c <..'•-* J *<'•>* .0-