Table Of Content

B U.S. Department of the Interior Bureau of Land Management L M BLM Alaska Technical Report 57 BLM/AK/ST-07/008+3091+940 January 2007 Mineral Assessment of the Delta River Mining District Area, East-central Alaska Peter E. Bittenbender, Kirby W. Bean, Joseph M. Kurtak, and James Deininger Jr. A l a s k a US DBUERPEAARUT OMFE LNANTD O MFA TNHAGEE MNETNETR IOR Mission Statement The Bureau of Land Management sustains the health, diversity and productivity of the public lands for the use and enjoyment of present and future generations. Authors Peter E. Bittenbender is a senior geologist in the Division of Energy and Minerals, Branch of Solid Min- erals, working in the Juneau - John Rishel Mineral Information Center, Bureau of Land Management, Juneau, Alaska. Kirby W. Bean is a geologist in the Division of Energy and Minerals, Branch of Solid Minerals, working in the Juneau - John Rishel Mineral Information Center, Bureau of Land Management, Juneau, Alaska. Joseph M. Kurtak is a senior geologist in the Division of Energy and Minerals, Branch of Solid Minerals, working in the Alaska State Offi ce, Bureau of Land Management, Anchorage, Alaska. James Deininger Jr. is a senior geologist in the Resources Branch of the Central Yukon Field Offi ce, Bureau of Land Management, Fairbanks, Alaska. Cover BLM geologist Jeff Borhauer evaluates the placer potential on McCumber Creek in the Delta River Mining District study area (Photo by Joseph M. Kurtak). Technical Reports Technical Reports issued by BLM-Alaska present results of research, studies, investigations, literature searches, testing, or similar endeavors on a variety of scientifi c and technical subjects. The results pre- sented are fi nal, or are a summation and analysis of data at an intermediate point in a long-term research project, and have received objective review by peers in the authorʼs fi eld. To request a copy of this or another BLM-Alaska scientifi c report, or for more information, please contact: BLM-Alaska Public Information Center 222 W. Seventh Ave., #13 Anchorage, AK 99513 (907) 271-5960 Juneau - John Rishel Mineral Information Center 100 Savikko Road, Mayfl ower Island Douglas, AK 99824 (907) 586-7751 Most BLM-Alaska scientifi c reports are also available for loan or inspection at Alaska Resources Li- brary and Information Services in Anchorage, (907) 27-ARLIS, and other major libraries in Alaska; USDI Resources Library in Washington, D.C.; the BLM National Business Center Library in Denver; and other select locations. A bibliography of scientifi c reports is online at www.blm.gov/ak. Related publications are also listed at www.blm.gov/ak/jrmic. Mineral Assessment of the Delta River Mining District Area, East-central Alaska By Peter E. Bittenbender Kirby W. Bean Joseph M. Kurtak James Deininger Jr. BLM-Alaska Technical Report 57 January 2007 U.S. Department of the Interior Bureau of Land Management Alaska State Offi ce 222 W. 7th Ave., #13 Anchorage AK 99513 Table of Contents List of Figures..........................................................................................................................................................v List of Tables.........................................................................................................................................................viii Abbreviations/Acronyms/Designations and Units of Measure..........................................................................xv Abstract....................................................................................................................................................................1 Introduction.............................................................................................................................................................2 Acknowledgments..................................................................................................................................................7 Purpose of Program..............................................................................................................................................9 Authorities...........................................................................................................................................................10 Priorities.............................................................................................................................................................10 Methodology.......................................................................................................................................................10 Location, Access, and Physiography....................................................................................................................11 Location..............................................................................................................................................................11 Access..................................................................................................................................................................11 Physiography......................................................................................................................................................13 Drainages.......................................................................................................................................................14 Elevations.......................................................................................................................................................14 Vegetation......................................................................................................................................................14 Glaciers..........................................................................................................................................................14 Climate...........................................................................................................................................................14 Land Status............................................................................................................................................................16 Previous Studies.....................................................................................................................................................20 Mining History.......................................................................................................................................................31 General Geology.....................................................................................................................................................38 Isotopic Age Dating................................................................................................................................................45 Magmatic Ages....................................................................................................................................................46 Alteration and excess argon ages.......................................................................................................................51 Airborne Geophysical Survey...............................................................................................................................52 Deposit Types.........................................................................................................................................................55 Mafic-ultramafic-hosted Ni-Cu-PGE deposits....................................................................................................56 Bird’s Beak....................................................................................................................................................64 Bird’s Foot.....................................................................................................................................................67 BOS................................................................................................................................................................69 i Mini U Landslide...........................................................................................................................................72 Boot Flap........................................................................................................................................................74 Dunite Diatreme.............................................................................................................................................77 Lower Crash...................................................................................................................................................79 West Crash.....................................................................................................................................................81 Crash..............................................................................................................................................................83 Notar...............................................................................................................................................................85 East Peak South Ridge...................................................................................................................................87 East Peak........................................................................................................................................................89 East Canyon...................................................................................................................................................91 East Broxson Gold.........................................................................................................................................93 North Rainy....................................................................................................................................................95 Hail Creek......................................................................................................................................................98 Foley’s..........................................................................................................................................................100 White Band..................................................................................................................................................102 Ann Fork......................................................................................................................................................104 East Rainy....................................................................................................................................................106 Rainy Breccia...............................................................................................................................................110 Marsha..........................................................................................................................................................112 Ann Creek....................................................................................................................................................114 Glacier Lake.................................................................................................................................................118 Emerick........................................................................................................................................................123 Upper Glacier...............................................................................................................................................129 Odie..............................................................................................................................................................131 Canwell Glacier............................................................................................................................................134 Cony Mountain.............................................................................................................................................138 Cony East.....................................................................................................................................................142 JS..................................................................................................................................................................144 GR 28-1........................................................................................................................................................146 Magnetite Cirque..........................................................................................................................................148 GR 28-20......................................................................................................................................................150 GR 28-19......................................................................................................................................................152 Miller Gulch Dikes.......................................................................................................................................154 Quartz Creek Head.......................................................................................................................................157 Summit Hill..................................................................................................................................................160 Antler...........................................................................................................................................................162 Fish Lake......................................................................................................................................................164 LFF...............................................................................................................................................................168 Eb No. 4.......................................................................................................................................................170 BM-75..........................................................................................................................................................172 Tres Equis....................................................................................................................................................174 WEG.............................................................................................................................................................176 Norel.............................................................................................................................................................178 Dunite Hill....................................................................................................................................................180 Amphi...........................................................................................................................................................182 Skarn Deposits..................................................................................................................................................185 Maclaren Glacier Lode.................................................................................................................................189 GR 14-19......................................................................................................................................................191 Green Wonder..............................................................................................................................................193 GR 14-12......................................................................................................................................................196 GR 14-8........................................................................................................................................................198 Moneta Porcupine........................................................................................................................................200 Rainy Creek Skarn.......................................................................................................................................202 West Rainy Skarn.........................................................................................................................................204 GR 14-4........................................................................................................................................................206 ii GR 14-16......................................................................................................................................................207 West Bowl....................................................................................................................................................208 Picrite Hill Skarn..........................................................................................................................................210 North Ann Creek..........................................................................................................................................212 GR 28-5........................................................................................................................................................213 West DAT....................................................................................................................................................214 Northland Mines...........................................................................................................................................217 Chisna Ridge................................................................................................................................................220 Volcanogenic Massive Sulfide Deposits............................................................................................................222 Miyaoka.......................................................................................................................................................224 West Hayes Glacier......................................................................................................................................228 East Hayes Glacier.......................................................................................................................................230 Roberts No. 1...............................................................................................................................................232 Roberts No. 2...............................................................................................................................................236 Placer Deposits.................................................................................................................................................241 Gulch (Active Stream) Placers.....................................................................................................................245 Alluvial Placers...........................................................................................................................................245 Bench Placers...............................................................................................................................................247 Tertiary Gravel Placers.................................................................................................................................248 Ptarmigan Creek...........................................................................................................................................253 Pillsbury.......................................................................................................................................................255 Ober Creek...................................................................................................................................................256 Savage Creek Tributaries.............................................................................................................................258 McCumber Creek Tributary.........................................................................................................................260 McCumber Creek.........................................................................................................................................262 Morningstar Creek.......................................................................................................................................266 McCumber Creek (Upper)...........................................................................................................................269 Pegmatite Creek...........................................................................................................................................271 Gunnysack Creek.........................................................................................................................................272 Broxson Gulch.............................................................................................................................................273 Broxson Gulch (Upper East Fork)................................................................................................................275 No Name Creek............................................................................................................................................277 Broxson Gulch (Lower East Fork)...............................................................................................................280 Specimen Creek (Lower).............................................................................................................................282 Specimen Creek (Upper)..............................................................................................................................284 Rainy Creek (West Fork).............................................................................................................................286 Rainy Creek..................................................................................................................................................288 Phelan Creek (Lower)..................................................................................................................................293 Miller Mine..................................................................................................................................................295 Gakona Glacier.............................................................................................................................................298 Chistochina River, West Fork......................................................................................................................299 Treasure Gulch.............................................................................................................................................301 Chistochina Glacier......................................................................................................................................303 Slate Creek...................................................................................................................................................307 Miller Gulch.................................................................................................................................................312 Round Wash.................................................................................................................................................316 Big Four Creek.............................................................................................................................................318 Ruby Gulch..................................................................................................................................................322 Quartz Creek................................................................................................................................................324 Bedrock Creek..............................................................................................................................................326 Limestone Creek..........................................................................................................................................328 Kraemer Creek.............................................................................................................................................330 Chisna River (Lower)...................................................................................................................................331 Chisna River.................................................................................................................................................334 Dempsey.......................................................................................................................................................338 iii Daisy Creek..................................................................................................................................................339 Red Bear.......................................................................................................................................................340 Chistochina River East Tributary.................................................................................................................342 Alder Creek..................................................................................................................................................344 Gunn Creek..................................................................................................................................................346 Dan Creek....................................................................................................................................................348 Gulkana River East Tributary.......................................................................................................................349 Phelan Creek (Upper)...................................................................................................................................351 Eureka Creek................................................................................................................................................354 Delta River...................................................................................................................................................356 Delta River-Garrett Creek............................................................................................................................358 Maclaren River (East Fork)..........................................................................................................................360 Boulder Creek..............................................................................................................................................362 One-Mile Creek............................................................................................................................................363 Other Deposit Types.........................................................................................................................................365 Ptarmigan.....................................................................................................................................................367 Tourmaline...................................................................................................................................................371 Hajdukovich Gold........................................................................................................................................374 Gunnysack....................................................................................................................................................376 Compass Creek.............................................................................................................................................379 GR 20-5........................................................................................................................................................381 GR 20-4........................................................................................................................................................383 GR 14-18......................................................................................................................................................384 Broxson Ridge Magnetite.............................................................................................................................388 GR 14-20......................................................................................................................................................393 GR 14-15......................................................................................................................................................395 Ghezzi..........................................................................................................................................................396 South Ann Copper........................................................................................................................................400 Joe Claims....................................................................................................................................................402 Red Knob.....................................................................................................................................................404 Eagle’s Nest.................................................................................................................................................406 GR 2-4..........................................................................................................................................................408 Verona Pick..................................................................................................................................................409 Verona Cirque..............................................................................................................................................411 GR 2-12........................................................................................................................................................415 GR 2-13........................................................................................................................................................417 Minya Moly..................................................................................................................................................418 GR 28-6........................................................................................................................................................419 GR 28-8........................................................................................................................................................421 Chistochina Airstrip.....................................................................................................................................424 Coppertone...................................................................................................................................................426 GR 28-27......................................................................................................................................................428 Azurite..........................................................................................................................................................430 Greenstone...................................................................................................................................................433 Tv Bas..........................................................................................................................................................435 LTLW...........................................................................................................................................................436 Landmark Gap Copper.................................................................................................................................439 Chitti Stain...................................................................................................................................................441 GR 13-9........................................................................................................................................................444 GR 13-6........................................................................................................................................................446 GR 13-3........................................................................................................................................................447 Summary..............................................................................................................................................................449 Select References..................................................................................................................................................455 iv Appendix A - Summary Information for Mines, Prospects, and Mineral Occurrences................................484 Abbreviations and descriptions.........................................................................................................................484 Table A-1. Summary information for mines, prospects, and occurrences in the Delta River Mining District study area..........................................................................................................................................................487 Appendix B – Analytical Results........................................................................................................................513 Sampling and Analytical Procedures................................................................................................................513 Sampling methods........................................................................................................................................513 Analytical methods.......................................................................................................................................513 Reporting methods.......................................................................................................................................514 Abbreviations...............................................................................................................................................514 Placer and sluice concentrate sample evaluation.............................................................................................517 Table B-1. Results of placer and sluice concentrate sample evaluations........................................................518 Table B-2. Analytical results for samples from mines, prospects, occurrences, and reconnaissance investigations....................................................................................................................................................519 Analytical methods and detection limits for samples from mines, prospects, occurrences, and reconnaissance investigations, Table B-2..............................................................................................................................590 Table B-3. Whole rock analyses for selected rock chip samples......................................................................591 Analytical methods and detection limits for whole rock samples, Table B-3..............................................602 Table B-4. Full suite PGE analyses for selected rock chip samples................................................................603 Analytical methods and detection limits for PGE samples, Table B-4........................................................608 Table B-5. REE and other trace element analyses for selected rock chip samples..........................................609 Analytical methods and detection limits for REE samples, Table B-5........................................................616 Table B-6. Latitude and longitude coordinates for BLM samples...................................................................617 Table B-7. Analytical results for reanalyzed USGS stream sediment samples................................................635 Sampling and analytical procedures for USGS stream sediment samples, Table B-7.................................648 Appendix C – Isotopic Age Date Discussion and Data.....................................................................................650 Discussion of individual samples......................................................................................................................650 Area West of Delta River.............................................................................................................................651 Area from Rainbow Mountain to Cony Mountain.......................................................................................652 Gulkana Glacier to Chistochina Glacier area...............................................................................................656 - Calc-alkaline Suite.....................................................................................................................................656 Gulkana Glacier to Chistochina Glacier area...............................................................................................658 - Alkalic Suite..............................................................................................................................................658 Area East of Summit Lake...........................................................................................................................661 Summary of isotopic age dating analysis..........................................................................................................675 List of Figures Figure 1. Location of the Delta River Mining District study area in East-central Alaska..........3 Figure 2. Jeff Borhauer with gold................................................................................................8 Figure 3. Junction of Alaska (to left) and Richardson highways at Delta Junction..................12 Figure 4. Paxson and the junction of Richardson (to right) and Denali highways....................13 Figure 5. Land status map of the Delta River study area..........................................................17 Figure 6. Map showing the locations of previous studies in the Delta River area....................21 v Figure 7. Mining camp on Slate Creek in early 1900's.............................................................31 Figure 8. Richardson Highway in 1923.....................................................................................32 Figure 9. Chistochina miners - probably around 1910..............................................................34 Figure 10. Tectonostratigraphic terranes in the Delta River study area....................................39 Figure 11. Location map of isotopic age date samples from the Delta River study area..........49 Figure 12. Location of the BLM airborne geophysical survey in the Delta River study area...53 Figure 13. Mafic-ultramafic complexes in the southern Delta River study area.......................57 Figure 14. View to west-northwest of the Bird's Beak and Bird's Foot occurrences................65 Figure 15. Ultramafic magmatic breccia at the North Rainy occurrence..................................96 Figure 16. Ultramafic clasts in ultramafic matrix in the North Rainy breccia..........................96 Figure 17. Magmatic layering in feldspathic peridotite at the East Rainy prospect................107 Figure 18. Sketch map of the East Rainy prospect..................................................................109 Figure 19. Sampling a sulfide lens at the Marsha occurrence.................................................113 Figure 20. Aerial view to west-northwest of the Ann Creek prospect....................................114 Figure 21. Glacier Lake prospect............................................................................................119 Figure 22. Sketch map of the Glacier Lake prospect..............................................................121 Figure 23. Sketch map of the Emerick prospect......................................................................125 Figure 24. Nevada Star drilling at the Canwell prospect, 2002...............................................136 Figure 25. View to east - northeast of the Cony Mountain and Cony East occurrences.........139 Figure 26. View to the west - northwest of the Cony Mountain occurrence...........................139 Figure 27. View to west - northwest of Cony Mountain occurrence......................................141 Figure 28. Arial view to west of the iron-stained lens at the GR 28-20 occurrence...............151 Figure 29. Layering defined by compositional variations in Fish Lake gabbro......................166 Figure 30. View to the south of the Tres Equis occurrence....................................................175 Figure 31. Skarn occurrences in the southern Delta River study area.....................................187 Figure 32. Geologist investigating the Green Wonder occurrence.........................................193 Figure 33. Polished hand sample from the Green Wonder occurrence...................................194 Figure 34. Geologist sampling the Moneta Porcupine occurrence..........................................201 Figure 35. Examining the Rainy Creek Skarn.........................................................................203 Figure 36. Mineralized outcrop at the West Rainy Skarn occurrence.....................................205 Figure 37. Iron-stained, sulfide-bearing rock of the Picrite Hill Skarn occurrence................211 Figure 38. Specular hematite in mineralized rock at the West DAT prospect........................215 Figure 39. Sampling at the Northland Mines prospect............................................................218 Figure 40. Aerial view of the main Miyaoka occurrence........................................................225 Figure 41. Sketch map of "outcrop #6" at the Miyaoka prospect............................................226 Figure 42. Photo of rusty outcrops (arrows) at the West Hayes Glacier occurrence..............229 Figure 43. View to south-southwest of the Roberts No. 1 occurrence....................................233 Figure 44. Tightly folded massive sulfide layer at the Robert's No. 1 occurrence..................234 Figure 45. Folded fold at the Roberts No. 2 occurrence.........................................................237 Figure 46. Sketch map of the Roberts No. 2 occurrence.........................................................239 Figure 47. Miners using sluice boxes to recover gold from shallow gulch placers on Slate Creek in the early 1900’s..........................................................................................................242 Figure 48. Placer occurrences in the Delta River study area...................................................243 Figure 49. Gulch and high-bench placer deposits in Miller Gulch.........................................245 Figure 50. Placer mining operations in the outwash plain of the Chistochina Glacier...........246 Figure 51. Placer mine site in low-bench gravels (arrows) on the Chisna River....................247 vi

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Figure 55. Junction of McCumber and Morningstar creeks. The studies provide important geoscience, mining engineering, and mineral economic information that In 1950 Mrs. Ruth A. Branson is listed as the owner of the
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B U.S. Department of the Interior Bureau of Land Management L M BLM Alaska Technical Report 57 BLM/AK/ST-07/008+3091+940 January 2007 Mineral Assessment of the Delta River Mining District Area, East-central Alaska Peter E. Bittenbender, Kirby W. Bean, Joseph M. Kurtak, and James Deininger Jr. A l a s k a US DBUERPEAARUT OMFE LNANTD O MFA TNHAGEE MNETNETR IOR Mission Statement The Bureau of Land Management sustains the health, diversity and productivity of the public lands for the use and enjoyment of present and future generations. Authors Peter E. Bittenbender is a senior geologist in the Division of Energy and Minerals, Branch of Solid Min- erals, working in the Juneau - John Rishel Mineral Information Center, Bureau of Land Management, Juneau, Alaska. Kirby W. Bean is a geologist in the Division of Energy and Minerals, Branch of Solid Minerals, working in the Juneau - John Rishel Mineral Information Center, Bureau of Land Management, Juneau, Alaska. Joseph M. Kurtak is a senior geologist in the Division of Energy and Minerals, Branch of Solid Minerals, working in the Alaska State Offi ce, Bureau of Land Management, Anchorage, Alaska. James Deininger Jr. is a senior geologist in the Resources Branch of the Central Yukon Field Offi ce, Bureau of Land Management, Fairbanks, Alaska. Cover BLM geologist Jeff Borhauer evaluates the placer potential on McCumber Creek in the Delta River Mining District study area (Photo by Joseph M. Kurtak). Technical Reports Technical Reports issued by BLM-Alaska present results of research, studies, investigations, literature searches, testing, or similar endeavors on a variety of scientifi c and technical subjects. The results pre- sented are fi nal, or are a summation and analysis of data at an intermediate point in a long-term research project, and have received objective review by peers in the authorʼs fi eld. To request a copy of this or another BLM-Alaska scientifi c report, or for more information, please contact: BLM-Alaska Public Information Center 222 W. Seventh Ave., #13 Anchorage, AK 99513 (907) 271-5960 Juneau - John Rishel Mineral Information Center 100 Savikko Road, Mayfl ower Island Douglas, AK 99824 (907) 586-7751 Most BLM-Alaska scientifi c reports are also available for loan or inspection at Alaska Resources Li- brary and Information Services in Anchorage, (907) 27-ARLIS, and other major libraries in Alaska; USDI Resources Library in Washington, D.C.; the BLM National Business Center Library in Denver; and other select locations. A bibliography of scientifi c reports is online at www.blm.gov/ak. Related publications are also listed at www.blm.gov/ak/jrmic. Mineral Assessment of the Delta River Mining District Area, East-central Alaska By Peter E. Bittenbender Kirby W. Bean Joseph M. Kurtak James Deininger Jr. BLM-Alaska Technical Report 57 January 2007 U.S. Department of the Interior Bureau of Land Management Alaska State Offi ce 222 W. 7th Ave., #13 Anchorage AK 99513 Table of Contents List of Figures..........................................................................................................................................................v List of Tables.........................................................................................................................................................viii Abbreviations/Acronyms/Designations and Units of Measure..........................................................................xv Abstract....................................................................................................................................................................1 Introduction.............................................................................................................................................................2 Acknowledgments..................................................................................................................................................7 Purpose of Program..............................................................................................................................................9 Authorities...........................................................................................................................................................10 Priorities.............................................................................................................................................................10 Methodology.......................................................................................................................................................10 Location, Access, and Physiography....................................................................................................................11 Location..............................................................................................................................................................11 Access..................................................................................................................................................................11 Physiography......................................................................................................................................................13 Drainages.......................................................................................................................................................14 Elevations.......................................................................................................................................................14 Vegetation......................................................................................................................................................14 Glaciers..........................................................................................................................................................14 Climate...........................................................................................................................................................14 Land Status............................................................................................................................................................16 Previous Studies.....................................................................................................................................................20 Mining History.......................................................................................................................................................31 General Geology.....................................................................................................................................................38 Isotopic Age Dating................................................................................................................................................45 Magmatic Ages....................................................................................................................................................46 Alteration and excess argon ages.......................................................................................................................51 Airborne Geophysical Survey...............................................................................................................................52 Deposit Types.........................................................................................................................................................55 Mafic-ultramafic-hosted Ni-Cu-PGE deposits....................................................................................................56 Bird’s Beak....................................................................................................................................................64 Bird’s Foot.....................................................................................................................................................67 BOS................................................................................................................................................................69 i Mini U Landslide...........................................................................................................................................72 Boot Flap........................................................................................................................................................74 Dunite Diatreme.............................................................................................................................................77 Lower Crash...................................................................................................................................................79 West Crash.....................................................................................................................................................81 Crash..............................................................................................................................................................83 Notar...............................................................................................................................................................85 East Peak South Ridge...................................................................................................................................87 East Peak........................................................................................................................................................89 East Canyon...................................................................................................................................................91 East Broxson Gold.........................................................................................................................................93 North Rainy....................................................................................................................................................95 Hail Creek......................................................................................................................................................98 Foley’s..........................................................................................................................................................100 White Band..................................................................................................................................................102 Ann Fork......................................................................................................................................................104 East Rainy....................................................................................................................................................106 Rainy Breccia...............................................................................................................................................110 Marsha..........................................................................................................................................................112 Ann Creek....................................................................................................................................................114 Glacier Lake.................................................................................................................................................118 Emerick........................................................................................................................................................123 Upper Glacier...............................................................................................................................................129 Odie..............................................................................................................................................................131 Canwell Glacier............................................................................................................................................134 Cony Mountain.............................................................................................................................................138 Cony East.....................................................................................................................................................142 JS..................................................................................................................................................................144 GR 28-1........................................................................................................................................................146 Magnetite Cirque..........................................................................................................................................148 GR 28-20......................................................................................................................................................150 GR 28-19......................................................................................................................................................152 Miller Gulch Dikes.......................................................................................................................................154 Quartz Creek Head.......................................................................................................................................157 Summit Hill..................................................................................................................................................160 Antler...........................................................................................................................................................162 Fish Lake......................................................................................................................................................164 LFF...............................................................................................................................................................168 Eb No. 4.......................................................................................................................................................170 BM-75..........................................................................................................................................................172 Tres Equis....................................................................................................................................................174 WEG.............................................................................................................................................................176 Norel.............................................................................................................................................................178 Dunite Hill....................................................................................................................................................180 Amphi...........................................................................................................................................................182 Skarn Deposits..................................................................................................................................................185 Maclaren Glacier Lode.................................................................................................................................189 GR 14-19......................................................................................................................................................191 Green Wonder..............................................................................................................................................193 GR 14-12......................................................................................................................................................196 GR 14-8........................................................................................................................................................198 Moneta Porcupine........................................................................................................................................200 Rainy Creek Skarn.......................................................................................................................................202 West Rainy Skarn.........................................................................................................................................204 GR 14-4........................................................................................................................................................206 ii GR 14-16......................................................................................................................................................207 West Bowl....................................................................................................................................................208 Picrite Hill Skarn..........................................................................................................................................210 North Ann Creek..........................................................................................................................................212 GR 28-5........................................................................................................................................................213 West DAT....................................................................................................................................................214 Northland Mines...........................................................................................................................................217 Chisna Ridge................................................................................................................................................220 Volcanogenic Massive Sulfide Deposits............................................................................................................222 Miyaoka.......................................................................................................................................................224 West Hayes Glacier......................................................................................................................................228 East Hayes Glacier.......................................................................................................................................230 Roberts No. 1...............................................................................................................................................232 Roberts No. 2...............................................................................................................................................236 Placer Deposits.................................................................................................................................................241 Gulch (Active Stream) Placers.....................................................................................................................245 Alluvial Placers...........................................................................................................................................245 Bench Placers...............................................................................................................................................247 Tertiary Gravel Placers.................................................................................................................................248 Ptarmigan Creek...........................................................................................................................................253 Pillsbury.......................................................................................................................................................255 Ober Creek...................................................................................................................................................256 Savage Creek Tributaries.............................................................................................................................258 McCumber Creek Tributary.........................................................................................................................260 McCumber Creek.........................................................................................................................................262 Morningstar Creek.......................................................................................................................................266 McCumber Creek (Upper)...........................................................................................................................269 Pegmatite Creek...........................................................................................................................................271 Gunnysack Creek.........................................................................................................................................272 Broxson Gulch.............................................................................................................................................273 Broxson Gulch (Upper East Fork)................................................................................................................275 No Name Creek............................................................................................................................................277 Broxson Gulch (Lower East Fork)...............................................................................................................280 Specimen Creek (Lower).............................................................................................................................282 Specimen Creek (Upper)..............................................................................................................................284 Rainy Creek (West Fork).............................................................................................................................286 Rainy Creek..................................................................................................................................................288 Phelan Creek (Lower)..................................................................................................................................293 Miller Mine..................................................................................................................................................295 Gakona Glacier.............................................................................................................................................298 Chistochina River, West Fork......................................................................................................................299 Treasure Gulch.............................................................................................................................................301 Chistochina Glacier......................................................................................................................................303 Slate Creek...................................................................................................................................................307 Miller Gulch.................................................................................................................................................312 Round Wash.................................................................................................................................................316 Big Four Creek.............................................................................................................................................318 Ruby Gulch..................................................................................................................................................322 Quartz Creek................................................................................................................................................324 Bedrock Creek..............................................................................................................................................326 Limestone Creek..........................................................................................................................................328 Kraemer Creek.............................................................................................................................................330 Chisna River (Lower)...................................................................................................................................331 Chisna River.................................................................................................................................................334 Dempsey.......................................................................................................................................................338 iii Daisy Creek..................................................................................................................................................339 Red Bear.......................................................................................................................................................340 Chistochina River East Tributary.................................................................................................................342 Alder Creek..................................................................................................................................................344 Gunn Creek..................................................................................................................................................346 Dan Creek....................................................................................................................................................348 Gulkana River East Tributary.......................................................................................................................349 Phelan Creek (Upper)...................................................................................................................................351 Eureka Creek................................................................................................................................................354 Delta River...................................................................................................................................................356 Delta River-Garrett Creek............................................................................................................................358 Maclaren River (East Fork)..........................................................................................................................360 Boulder Creek..............................................................................................................................................362 One-Mile Creek............................................................................................................................................363 Other Deposit Types.........................................................................................................................................365 Ptarmigan.....................................................................................................................................................367 Tourmaline...................................................................................................................................................371 Hajdukovich Gold........................................................................................................................................374 Gunnysack....................................................................................................................................................376 Compass Creek.............................................................................................................................................379 GR 20-5........................................................................................................................................................381 GR 20-4........................................................................................................................................................383 GR 14-18......................................................................................................................................................384 Broxson Ridge Magnetite.............................................................................................................................388 GR 14-20......................................................................................................................................................393 GR 14-15......................................................................................................................................................395 Ghezzi..........................................................................................................................................................396 South Ann Copper........................................................................................................................................400 Joe Claims....................................................................................................................................................402 Red Knob.....................................................................................................................................................404 Eagle’s Nest.................................................................................................................................................406 GR 2-4..........................................................................................................................................................408 Verona Pick..................................................................................................................................................409 Verona Cirque..............................................................................................................................................411 GR 2-12........................................................................................................................................................415 GR 2-13........................................................................................................................................................417 Minya Moly..................................................................................................................................................418 GR 28-6........................................................................................................................................................419 GR 28-8........................................................................................................................................................421 Chistochina Airstrip.....................................................................................................................................424 Coppertone...................................................................................................................................................426 GR 28-27......................................................................................................................................................428 Azurite..........................................................................................................................................................430 Greenstone...................................................................................................................................................433 Tv Bas..........................................................................................................................................................435 LTLW...........................................................................................................................................................436 Landmark Gap Copper.................................................................................................................................439 Chitti Stain...................................................................................................................................................441 GR 13-9........................................................................................................................................................444 GR 13-6........................................................................................................................................................446 GR 13-3........................................................................................................................................................447 Summary..............................................................................................................................................................449 Select References..................................................................................................................................................455 iv Appendix A - Summary Information for Mines, Prospects, and Mineral Occurrences................................484 Abbreviations and descriptions.........................................................................................................................484 Table A-1. Summary information for mines, prospects, and occurrences in the Delta River Mining District study area..........................................................................................................................................................487 Appendix B – Analytical Results........................................................................................................................513 Sampling and Analytical Procedures................................................................................................................513 Sampling methods........................................................................................................................................513 Analytical methods.......................................................................................................................................513 Reporting methods.......................................................................................................................................514 Abbreviations...............................................................................................................................................514 Placer and sluice concentrate sample evaluation.............................................................................................517 Table B-1. Results of placer and sluice concentrate sample evaluations........................................................518 Table B-2. Analytical results for samples from mines, prospects, occurrences, and reconnaissance investigations....................................................................................................................................................519 Analytical methods and detection limits for samples from mines, prospects, occurrences, and reconnaissance investigations, Table B-2..............................................................................................................................590 Table B-3. Whole rock analyses for selected rock chip samples......................................................................591 Analytical methods and detection limits for whole rock samples, Table B-3..............................................602 Table B-4. Full suite PGE analyses for selected rock chip samples................................................................603 Analytical methods and detection limits for PGE samples, Table B-4........................................................608 Table B-5. REE and other trace element analyses for selected rock chip samples..........................................609 Analytical methods and detection limits for REE samples, Table B-5........................................................616 Table B-6. Latitude and longitude coordinates for BLM samples...................................................................617 Table B-7. Analytical results for reanalyzed USGS stream sediment samples................................................635 Sampling and analytical procedures for USGS stream sediment samples, Table B-7.................................648 Appendix C – Isotopic Age Date Discussion and Data.....................................................................................650 Discussion of individual samples......................................................................................................................650 Area West of Delta River.............................................................................................................................651 Area from Rainbow Mountain to Cony Mountain.......................................................................................652 Gulkana Glacier to Chistochina Glacier area...............................................................................................656 - Calc-alkaline Suite.....................................................................................................................................656 Gulkana Glacier to Chistochina Glacier area...............................................................................................658 - Alkalic Suite..............................................................................................................................................658 Area East of Summit Lake...........................................................................................................................661 Summary of isotopic age dating analysis..........................................................................................................675 List of Figures Figure 1. Location of the Delta River Mining District study area in East-central Alaska..........3 Figure 2. Jeff Borhauer with gold................................................................................................8 Figure 3. Junction of Alaska (to left) and Richardson highways at Delta Junction..................12 Figure 4. Paxson and the junction of Richardson (to right) and Denali highways....................13 Figure 5. Land status map of the Delta River study area..........................................................17 Figure 6. Map showing the locations of previous studies in the Delta River area....................21 v Figure 7. Mining camp on Slate Creek in early 1900's.............................................................31 Figure 8. Richardson Highway in 1923.....................................................................................32 Figure 9. Chistochina miners - probably around 1910..............................................................34 Figure 10. Tectonostratigraphic terranes in the Delta River study area....................................39 Figure 11. Location map of isotopic age date samples from the Delta River study area..........49 Figure 12. Location of the BLM airborne geophysical survey in the Delta River study area...53 Figure 13. Mafic-ultramafic complexes in the southern Delta River study area.......................57 Figure 14. View to west-northwest of the Bird's Beak and Bird's Foot occurrences................65 Figure 15. Ultramafic magmatic breccia at the North Rainy occurrence..................................96 Figure 16. Ultramafic clasts in ultramafic matrix in the North Rainy breccia..........................96 Figure 17. Magmatic layering in feldspathic peridotite at the East Rainy prospect................107 Figure 18. Sketch map of the East Rainy prospect..................................................................109 Figure 19. Sampling a sulfide lens at the Marsha occurrence.................................................113 Figure 20. Aerial view to west-northwest of the Ann Creek prospect....................................114 Figure 21. Glacier Lake prospect............................................................................................119 Figure 22. Sketch map of the Glacier Lake prospect..............................................................121 Figure 23. Sketch map of the Emerick prospect......................................................................125 Figure 24. Nevada Star drilling at the Canwell prospect, 2002...............................................136 Figure 25. View to east - northeast of the Cony Mountain and Cony East occurrences.........139 Figure 26. View to the west - northwest of the Cony Mountain occurrence...........................139 Figure 27. View to west - northwest of Cony Mountain occurrence......................................141 Figure 28. Arial view to west of the iron-stained lens at the GR 28-20 occurrence...............151 Figure 29. Layering defined by compositional variations in Fish Lake gabbro......................166 Figure 30. View to the south of the Tres Equis occurrence....................................................175 Figure 31. Skarn occurrences in the southern Delta River study area.....................................187 Figure 32. Geologist investigating the Green Wonder occurrence.........................................193 Figure 33. Polished hand sample from the Green Wonder occurrence...................................194 Figure 34. Geologist sampling the Moneta Porcupine occurrence..........................................201 Figure 35. Examining the Rainy Creek Skarn.........................................................................203 Figure 36. Mineralized outcrop at the West Rainy Skarn occurrence.....................................205 Figure 37. Iron-stained, sulfide-bearing rock of the Picrite Hill Skarn occurrence................211 Figure 38. Specular hematite in mineralized rock at the West DAT prospect........................215 Figure 39. Sampling at the Northland Mines prospect............................................................218 Figure 40. Aerial view of the main Miyaoka occurrence........................................................225 Figure 41. Sketch map of "outcrop #6" at the Miyaoka prospect............................................226 Figure 42. Photo of rusty outcrops (arrows) at the West Hayes Glacier occurrence..............229 Figure 43. View to south-southwest of the Roberts No. 1 occurrence....................................233 Figure 44. Tightly folded massive sulfide layer at the Robert's No. 1 occurrence..................234 Figure 45. Folded fold at the Roberts No. 2 occurrence.........................................................237 Figure 46. Sketch map of the Roberts No. 2 occurrence.........................................................239 Figure 47. Miners using sluice boxes to recover gold from shallow gulch placers on Slate Creek in the early 1900’s..........................................................................................................242 Figure 48. Placer occurrences in the Delta River study area...................................................243 Figure 49. Gulch and high-bench placer deposits in Miller Gulch.........................................245 Figure 50. Placer mining operations in the outwash plain of the Chistochina Glacier...........246 Figure 51. Placer mine site in low-bench gravels (arrows) on the Chisna River....................247 vi

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Figure 55. Junction of McCumber and Morningstar creeks. The studies provide important geoscience, mining engineering, and mineral economic information that In 1950 Mrs. Ruth A. Branson is listed as the owner of the
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