Mineral Assessment of the Delta River Mining District Area, East-central Alaska BLM

696 Pages·2007·13.75 MB·English

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U.S. Department of the Interior
Bureau of Land Management L
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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.
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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:
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Anchorage, AK 99513
[phone]
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100 Savikko Road, Mayfl ower Island
Douglas, AK 99824
[phone]
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
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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
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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
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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
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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
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