GEOLOGY AND MINERAL DEPOSITS OF SOUTHEASTERN ALASKA

428 Pages·2011·37.94 MB·English

DEPARTMENT OF THE INTERIOR
Ray Lyman Wilbur, Secretary
U. S. GEOLOGICAL SURVEY
George Otia Smith. Director
m 800
GEOLOGY AND MINERAL DEPOSITS
OF SOUTHEASTERN ALASKA
BY
A. F. BUDDINGTON
AND
THEODORE CHAPIN
!. .! » * ! ! *. ' *
- -. !
' A «!
« » O » » * « * ^ * * "
«>V *9 * 0 « «9 >« 0 t «O * 'V *
UNITED STATES
GOVERNMENT PRINTING OFFICE
WASHINGTON: 1929
ADDITIONAL COPIES
OF THIS PUBLICATION MAT BE PROCURED FROM
THE SUPERINTENDENT OF DOCUMENTS
U. 8. GOVERNMENT PRINTING OFFICE
WASHINGTON, D. C.
AT
85 CENTS PEE COPY (Paper covers
CONTENTS
Introduction..---------. ___________________________ _______________
Scope of report ___.__-_-____-__________-_--__-___-_________
Nature of the field work ____ ______________________________
Responsibility of authorship... ______________________________
Acknowledgments. _ _ ________________________________________
Earlier explorations and surveys, by Theodore Chapin.___ _________
Notes on history of mining development- _____-______----__--____
Geography _.
Location and extent___-_______-___________________---_____--__
Population and settlements... -..___ ____________---_--______
Transportation _ ______ -__________-______________-___________
Climate.---. ----_----_-_-----_--------_---------------_--____
Vegetation and timber supply, by Theodore Chapin .
Agricultural land--__--__-___________.___ _ __-____---_-_______
Water power _ ____________________________________________
Outline of geology _________ _______________________ ________
Main structural features. _________ _________________________
Bedrock geology ___.____-_____--____.-._ __._.___--_________
Physiographic history.. _ ___________________ __________________
Topography __________
General features ________ _______ __ .IVL^i'i'JiLi. _> ___._
Pleistocene glaciation_______ ___________________________________
Height of the ice surface________-_________-_.___--_________
Direction of flow.- ________ __ _ _________________________
Valleys. ___..__ ______________ _______ ______ ___
Fiords_________ _ .. ____ . _______ __ ______
Cirques- .. . ___ __ ___ _ ___ _
Modern glaciers.... _ ... __ _________________________________
Marine erosion. __ ________________________ _________
Sea-cut benches and platforms.______________________. -_-__--___
Karst topography __ __
Relation of topography to structure __ _____ _ __ _ ____________
The rocks __ _ _ _ _ ______._. __ ... _. _
Stratigraphic column, by Theodore Chapin and A. F. Buddington___
General lithology _ ___!-. _ _____ __ __________.____-__--__.__
Volcanic rocks____________________________________________
Graywacke------_---_--_--_--_-__-__-_---___------_-_-.__
Sandstone __ __-__-___-__-________________---_--_____
Limestone-________--_____________________________________
Conglomerate. _________________________________________
Intraformational conglomerate.------.--..-,---------------.
Slate. ___________________________________
Chert_.____. ____-____---__ ...__-_-.__._. .._______......
Phyllite, schist, and gneiss _ ___._...___..-______-_-__--____
nz
IV COXTEBTTS 4
The rocks Continued. Page *
Wales group, by Theodore Chapin and A. F. Buddington_________ 45
Wrangell-Revillagigedo belt of metamorphic rocks.________________ 49
Character and distribution________________________________ 49
Ketchikan district.._______________________________________ 52
Vicinity of Wrangell Island...._____________________________ 57 4
Le Conte Bay___________________________________________ 59
Thomas Bay....____________________________ 60 A
Port Houghton__ ____________________________ 66
Hobart and Windham Bays______-____-__-______________--_ 68 *
Holkham Bay and Tracy Arm__________________________.._ 68
Juneau district..... ____________--___-____-_-. 70
Schistose greenstone and phyllite between Port Houghton and
Juneau... . __>-______________________--_____-_-_ 71
Age ....... . __.___._____._____________.__---- 73 _,
Ordovician rocks._____________________________________________ 74
Prince of Wales and neighboring islands.____________________ 74 \
Character and occurrence.______________________________ 74
Fossils..------.__-_--____-_--_____-_.-_--__-_-----_ 75
Kuiu Island-_---_-__-__-_-_--__-_-_-_-___-_-_-_--___.--_- 77
Silurian rocks__---__-_-_-_-_-_---.______-___..___-___..__.--__ 79 *
Distribution._____________________________________________ 79
Lower Silurian slate and graywacke____-____-_-___-_-___-___ 81
Volcanic rocks and conglomerate__-___-_-_____---_-_-___---_ 82 '^
Limestone and conglomerate._______-___-______-__-___.---- 83
Shale_________--_--_---__..____.___._--_______-__._-_.-- 88
Sandstone and graywacke._________________________________ 88
Dikes....-._-..______________.___.---._______ 90
Age and correlation______________________________.________ 90
Devonian rocks________________-_______-__________-_---__---_ 94 *
Distribution and character.________________________________ 94
Middle Devonian rocks-___________________________________ 94
Southern Ketchikan district, by Theodore Chapin_______. 94 .4-
Northern Ketchikan district_-_--_-____-------___----. 101
Middle (?) and Upper Devonian rocks of northern part of
Kupreanof Island_-_--------_--__i--____-_--__-___----__ 106
Upper Devonian rocks of other parts of southeastern Alaska, >*
by Theodore Chapin______________________.____________- 107
Carboniferous rocks.--_-____--___-_-__--__-_____--__-_-___-_-- 109 *
Distribution and character.________________________________ 109
Mississippian rocks______-_-______--___-____--__--__------ 110 .
Distribution and character_____-_-___-___-------_-_--_- 110
Age and correlation.___________._.._.______________-___ 110
Pennsylvanian (?) rocks, by Theodore Chapin.________-__--__ 117
Permian rocks____-_.__-_--________-----___---------__---- 118
Character and occurrence._____-___-______--_--_-__-_-_ 118
Age and correlation____-^__________-______-_-___---__- 121
Lower division of the Permian___________-_-_______--.- 122
Upper division of the Permian_________________---_-__- 127
Triassic rocks (Upper Triassic)_________-----__-__----_-_-_----- 130
Distribution. _ ______-________--_____________---_---_-_---- 130
Character and stratigraphic relations______-___i-______-__--_ 131
Gravina and Revillagigedo Islands, by Theodore Chapin....... 132
Screen Islands._________-__________-_-_-____-----__-__---_ 134
t CONTENTS
** The rocks Continued.
Triassic rocks (Upper Triassic) Continued.
Keku Strait...... _.__--._.-..__---_-.--.-------.-_-.----- 134
Admiralty Island ______________________-______--_--------- 137
Volcanic rocks with Pseudomonolis-bearing beds _ ____________ 138
t Volcanic rocks of Kuiu and Hound Islands. __________________ 142
Age and correlation, by Theodore Chapin ____________________ 144
* Jurassic (?) rocks_________________. ___________________________ 156
Distribution and character. ________________________________ 156
* Sedimentary division________________________________-_-___ 157
Juneau district _ _____________________________________ 157
Seymour Canal-Fanshaw-Kupreanof area _ ____-_____-_-- 158
Kupreanof- Mitkof-Etolin Islands area ___________________ 163
Chichagof Island_____--_____---__-__-__-_------_------ 164
»' Felsite volcanic rocks. __.__-______-_-___-___-___-_---------- 165
Greenstone volcanic rocks. __________ __ ___________________ 165
* Distribution.. ________________________---_---.-_------ 165
Ketchikan district, by Theodore Chapin_ __,________-___-- 167
Age and correlation____________________. ______________ 168
Upper Jurassic or Lower Cretaceous intrusive rocks. ______________ 173
* General character. ________________________________________ 173
Border zone east of the Coast Range batholith.. _ _____________ 175
Coast Range batholith__----_______---_-_____-_-_---_---_-_ 177
^ Wrangell-Revillagigedo belt of metamorphic rocks--___-_-_---_ 181
Prince of Wales-Chichagof belt... _______ ... ________ 183
Kuiu-Heceta belt. ________________________________________ 186
Dall-Baranof belt._... ._.._...._- _ ....... ___ ..__._____ 186
Rock types_-_-_______-___________-_____________-_-_------ 188
Ultrabasic group. _-_________---_-_______-_-_---_-----. 188
* General features............ _________________ 188
Dunite.. ___________________________ 190
___-_________-_.______. ________________ 192
_-_-___-___-_____-_____-_-_- _ ______ 193
Hornblendite... __ _ ___ - ____ - _______ 194
Gabbro--.____ _ .-.__ ____________________ 199
Gabbro-diorite ___________________________ 201
Diorite __ ___ _________________________ 202
Monzodiorite. ____-_________-_-_-_-_____-___-_-_-_-_-_ 204
Syenite. ______________________________ 206
Quartz diorite. ______ ___ ._ __ ._ __ __ __ _________ 207
Granodiorite _ ___-_-___-____--_---_-_----__-_-_------ 214
Quartz monzonite_---_-_-___-_---_---_---_-_-_-------- 220
Granite _______________________________ 222
Pegmatite and aplite________-_-_______-___-___-------- 223
Malchite dikes. ________ _ _____________ ___ _ 229
Lamprophyre dikes _ _________________________________ 229
Structure of the intrusive rocks___-_-___-____-____-___---_-_ 231
Origin of variations in intrusive rocks_________ _______________ 235
Differentiation in place________________-_-_-_---_-_--_- 236
Successive intrusions-------------.-.------------------ 239
VI CONTENTS
The rocks Continued.
Upper Jurassic or Lower Cretaceous intrusive rocks Continued.
Origin of variations in intrusive rocks Continued. Page
Summary of relations of variants__________________ 242
Field relations____________________ ._ 242
Order of crystallization._________________________ 244
Rate of cooling and mineralizers____________________ 248
Ultrabasic rocks______._______________- ___________ 248
Gabbro, diorite, and alkalic-siliceous rocks _______________ 250
Age____________________________________ 252
Lower Cretaceous (?) rocks.________..________--_-_--__---_----_ 253
Distribution and character___--__________-__-_-_---__-.--__ 253
Gravina Island, by Theodore ChapiD______________________ 254
Rocky Bay, Etolin Island_________________-_-_--__-_-____ 255
Point Hamilton and vicinity.______________________________ 256
Pybus Bay________________________________ 257
Age and correlation_______________________________________ 258
Tertiary rocks.___-___-_________-_____________.-__-----__---_. 260
Eocene rocks_-__-__-______________________-______------__ 260
Distribution and character______________-.______-_______ 260
Basal conglomerate and sandstone.___________________ 262
Conglomerate of lava cobbles and rhyolitic flows, breccia,
and tuff _______________________________ 263
Basaltic and andesitic lava flows and associated rocks. _____ 266
Origin________________________..___...___ 267
Age.......--..___-___-_____-_-._- -_---_- .-_ 267
Pliocene (?) deposits___________.__________________________ 269
Lituya Bay_-____._______________________ 269
Suemez Is]and-__________-__________-_____---_--_---_- 270
Intrusive rocks___________________________________________ 271
Distribution_________:_________________ 271
Dikes... ____________________________________________ 271
Diabase....-____ ________ _ 273
Dacite porphyry___________.__________________________ 273
Olivine gabbro-________________________.______________ 274
Analcite gabbro.._______________-_-____------_------__ 274
Granite porphyry_____________________________________ 275
Quaternary rocks______________________________.._-_----------- 275
Glacial deposits----_______________________________-------- 275
Marine deposits and terraces_________________-_-_____-_--__ 276
Basalt and tuff..........._________________.----_. 278
Delta and current deposits____________________-____--_--___ 279
Relations between formations__-___-_____-----------___-------- 281
Wales group (Ordovician, Silurian, and Devonian)____________ 281
Middle and Upper Devonian, by Theodore Chapin_________>_. 283
Devonian and Carboniferous._______________________------_ 284
Paleozoic and Upper Triassic.______________________----_--_ 284
Unconformity within the Upper Triassic_____________________ 285
Jurassic (?), Lower Cretaceous (?), and older formations.______ 285
Upper Jurassic or Lower Cretaceous intrusive rocks and Mesozoic
orogeny._______________________________________________ 287
Tertiary and older formations.______________-____-___-----_ 288
Quaternary ______________________________________________ 289
Summary ________________________________________________ 289
» CONTENTS VH
I* Page
Structure. _------__.___-.______________________ 289
* General features_____-_-------__---_____---__-_--___________-_ 289
Jurassic (?) rocks of the Hyder district..... 292
Coast Range batholith and Wrangell-Revillagigedo belt of meta-
^ morphic rocks-____--_-----______-_-__---______-_-_--_-_____ 292
Juneau synclinorium-_________________________________________ 298
P- Duncan anticlinorium__________.__________________________ 299
Keku-Gravina synclinorium._________________________________ 300
^ Gravina synclinorium, by Theodore Chapin___.._________.. 300
Rocky Bay area, Etolin Island.-..__-_-_.______--__-_._-_ 302
Keku synclinorium_______________________________________ 302
Frederick Sound axis of cross folding__________________________ 303
Prince of Wales-Kuiu anticlinorium.________________________ 304
i General features_-_-______-___-_______________________ 304
Kuiu anticlinorium____________________________________ 307
P North coast of Prince of Wales Island---__-__---_-_----___-_ 307
Shakan Bay syncline__________-____-______-_-_____________ 308
Kosciusko-Tuxekan-Heceta synclinorium-_________________ 308
Maurelle Islands____________________________ 309
t San Fernando anticlinorium______________________ _______ 310
Kashevarof anticlinorium______________-___________________ 310
Vicinity of San Alberto and Bucareli Bays......__--____._. 311
r Southern half of Prince of Wales Island and adjacent islands,
by Theodore Chapin____________________ _____ 311
Dolomi-Sulzer anticlinorium, by Theodore Chapin__________ 314
Dall anticlinorium-_____________ _______________._ 314
Chichagof-Glacier Bay anticlinorium-_________ ___________ 315
Freshwater Bay syncline________.___-___________ 315
* Sitka Mesozoic belt____________________________________ 315
Mineral deposits.________________.____________ 316
Types of deposit_____________________________ 316
. Metalliferous deposits.___________________________ 320
Ores and associated minerals__________-___________________ 320
Gold___________________________ __________________ 320
Copper______________________________ 322
p- Iron__________________________________ 325
Silver and lead___________________________ 327
* Zinc_________________________________ 328
Nickel...____________________________________ 329
Molybdenum__________________________ 329
Tungsten.____________________________ 330
Antimony-______ _ 331
Y Titanium...___________________________ 331
Arsenic.-______________________________ 331
h Bismuth..____________________________ 332
Gypsum.._____________.______________ 332
* Garnet_______________________________ 332
Barite_______________________________ 333
Graphite. ______________________________ 333
^ Mica.________________________________ 334
Sillimanite, cyanite, and andalusite__________________ 335
^ Quartz... ____.___ _....__...___ 335
Carbonates. ______________ __________ 335
CONTENTS
Mineral deposits Continued.
Metalliferous deposits Continued.
Ores and associated minerals Continued. Page
Epidote____ ______.._____________________ 336
Pyroxene. _ ___________________________ 336
Amphibole------______-----___-__________ 337 -«
Albite. __________-____.___-____.___________ 337
Chlorite-_________.__________________________________ 337 *
Apatite______________________________ 337
Tourmaline....__________________________ 338 *
Lithologic and stratigraphies association of ore deposits-_______ 338
Wales group, by Theodore Chapin_____________________ 338
Wrangell-Revillagigedo belt of metamorphic rocks _ _______ 339
Ordovician and Silurian graywacke and slate_____________ 340
Silurian greenstone and limestone...--_________________ 340 -4
Middle Devonian rocks, by Theodore Chapin.___________ 341
Upper Devonian rocks, by Theodore Chapin_____________ 341 *
Mississippian rocks, by Theodore Chapin ________________ 341
Permian rocks, by Theodore Chapin_____________________ 342
Triassic rocks, by Theodore Chapin _____________________ 342
Jurassic (?) greenstone and slate._______________________ 342
Jurassic (?) graywacke and slate________--____-__-______ 343
Upper Jurassic or Lower Cretaceous intrusive rocks.______ 344
Gold________________________-_.______ 345
Gold-silver-lead._____________________ 347
Molybdenum________ ___________________________ 347
Nickel-copper____________________________ ___ 348
Copper and copper-palladium...._________________ 351
Iron.._____________________________ 351
Chromium. ______________________________________ 353
Lower Cretaceous (?) rocks____________________ ____ 353
Tertiary rocks______________________________________ 353
Quaternary deposits_________________________ 354
Belts of mineralization___________________________________ 356
Eastern border belt__________________________________ 357
Central Coast Range batholith______________________ 358
Western belt of schist and gneiss._______-_____________ 360
Zinc___-___________________________ 361
Silver-lead..________________________ 362
Gold____-___________________________._______. 362
Graphite.__________________________ 363
Garnet..____________________________ 363
Juneau gold belt______________________ 364
Funter Bay-Hawk Inlet belt.._________________ 366
Prince of Wales belt..._____..__.___________ 366
Copper____________________________ 368
Gold___- ______________ _ _ ____-_-___ 370
Chichagof gold belt___.____________________._ 371
Sitka belt___-________________________________ 373
Genetic relations of the metalliferous deposits_______________ 373
Character of country rock__________-_-___---_-__------- 374
o Type of associated igneous rock and type or stage of mag-
matic differentiation____________________--__-------_ 375
Mode of occurrence of igneous mass______________------_ 382
ILLUSTRATIONS IX
Mineral deposits Continued.
Metalliferous deposits Continued.
Genetic relations of the metalliferous deposits Continued. Page
Temperature and pressure____________________________ 383
Hy drothermal alterations in the igneous rocks ____________ 386
Conclusions ________________________________________ 389
Limestone.. __________________________________________________ 390
Building and ornamental stone________________________________ 393
Index.. ___________________________________-___-._ 395
ILLUSTRATIONS
Page
PLATE 1. Geologic map of a part of southeastern Alaska________ In pocket.
2. Generalized geologic map of southeastern Alaska..____ In pocket.
3. Coast Range topography, Hyder district: A, View near lower
part of Chickamin Glacier; B, View near head of Chickamin
Glacier._______________________________ 22
4. Mountains of Prince of Wales Island: A, Panorama from head
of Klakas Inlet; B, Panorama from head of Twelvemile Arm. 22
5. A, Cirque occupied by glacier 7^ miles N. 70° W. of Whiting
Point, Port Snettisham; B, Cirque occupied by lake, Kane
Peak, Kupreanof Island________________________________ 22
6. A, Rock ridge forming front edge-or lip of cirque occupied by
lake at head of Cann Creek, Lisianski Inlet, Chichagof Island;
B, Ridge between the heads of two cirques, Kane Peak,
Kupreanof Island______________________________ . 22
7. A, Glacial lake in valley of Cascade Creek in Coast Range near
Thomas Bay; B, Glaciated surface of quartz diorite showing
roches moutonne'es, Thomas Bay________________________ 22
8. A, Rounded top of mountain below level of Pleistocene glacia-
tion, Tracy Arm, Holkham Bay; B, Serrate peak of moun
tain above level of Pleistocene glaciation, near head of
Chickamin Glacier, Hyder district.______________________ 22
9. A, Tracy Arm, a fiord in southeastern Alaska; B, Glacier-
faceted headlands along fiord on east side of Baker Island __ 30
10. A, U-shaped glaciated valley with recent gorge in the bottom,
Bergs Creek, Wrangell district; B, Pass at head of Goat
Creek, Hyder district___________________________-______ 30
11. A, Baird Glacier and outwash plain, Thomas Bay; B, Trees
overthrown by advance of Baird Glacier in 1923___________ 30
12. A, Icebergs from Baird Glacier buried in outwash plain; B,
Pit lake being formed in outwash plain of Baird Glacier by
melting of iceberg____________________________________ 30
13. A, Dawes Glacier, Endicott Arm; B, North Dawes Glacier, at
the head of Endicott Arm______________________________ 30
14. A, Remnants of three uplifted wave-cut terraces in lime
stone, Keku Islets; B, Elevated wave-cut bench in limestone,
Cornwallis Peninsula, Kuiu Island...___________________ 30
15. A, Coastal plain along southwest coast of Annette Island; B,
Elevated wave-cut bench opposite Dolomi, Prince of Wales
Island. _______________________________ 38
X - ILLTJSTBATIONS
Page
PLATE 16. A, Closely folded limestone of the Wales group, Dall Island;
B, Greenstone schist of the Wales group, Port Johnson,
Price of Wales Island-_______________________ 38
17. A, Mount Calder, Prince of Wales Island; B, Silurian con
glomerate, Kuiu Island_______________________________ 86
18. A, Massive white Silurian (?) limestone, Dall Island; B, Flow
breccia of Middle Devonian age, Hessa Peninsula, Prince
of Wales Island....__________________._____ 86
19. A, Black chert of Mississippian age, Madre de Dios Island;
B, Fossiliferous massive white limestone of Pennsylvanian
age, Soda Bay, Prince of Wales Island__________________ 118
20. A, Permian limestone bluffs on northeast side of Saginaw Bay,
Kuiu Island; B, Overturned fold in graywacke and phyllite,
east side of Frederick Sound___________-________________ 118
21. Silicified stump and trunk of tree of Eocene age, Kuiu Island,
4 miles east-southeast of Point Camden__________________ 262
22. Structure sections in southeastern Alaska.__________________ 294
FIGURE 1. Diagrammatic structure section of Silurian and adjacent rocks
on east coast of Dall Island___________________________ 283
2. Structure section on Clover Bay, Prince of Wales Island.____ 313
3. Diagram showing relative amounts of different metals deposited
in lodes at six different positions on their parent batholiths__ 383