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Ministry of Energy Mines and Responsible for Core Review

114P-O Geological Legend

 

Tatshenshini-Yakutah

INTRUSIVE ROCKS

Og

Oligocene intrusive rocks of the Tkope Suite, undifferentiated (114PE).

eTg

Eocene intrusive rocks of the Seward Plutonic Suite (Dodds and Campbell, 1992), undifferentiated; mainly tonalite and granodiorite.
KTg Late Cretaceous to Eocene granitoid rocks of the Coast Mountains, undifferentiated (114P/E and 104M).
KTb Pyroxene gabbro.
JKg Late Jurassic and Early Cretaceous granitoid rocks of the Saint Elias plutonic suite (Campbell and Dodds, 1983), undifferentiated (114P/W and 114O).
JKgd Dominantly granodiorite.
JKg Dominantly diorite.
PMg Undifferentiated greenstone, gabbro and diorite of presumed Paleozoic and/or Triassic age.  Several different units represented.  Includes greenstone, gabbro and diabase of the "Squaw-Datlasaka Ranges gabbro-diabase sills" division of Campbell and Dodds (1983), of presumed late Paleozoic or Mesozoic age (114P/E).
QUARTERNARY DEPOSITS
Qg Glacial ice cover.
Qal Extensive areas of unconsolidated glacial till and poorly sorted alluvium.

STRATIFIED ROCKS OVERLYING ALEXANDER, WRANGELLIA AND TAKU TERRANES

Nv Volcanic rock ranging from basalt to rhyodacite flows, tuff and hypabyssal equivalents, correlated with the Wrangell Lavas of Miocene age (114P).
eTs Undifferentiated nonmarine sandstone, siltstone, shale, claystone, conglomerate and breccia of Paleocene and Eocene age.  (May be correlated in part with the Amphitheatre Formation of Eisbacher, 1976) (114P).
eTv Undifferentiated volcaniclastic rocks of Paleocene and Eocene Age (114P).
JKD Undifferentiated turbiditic shale, siltstone, and sandstone of the Dezadeash Group (114P/E).

CHUGACH TERRANE AND TARR INLET SUTURE ZONE (114O)

KVm Metamorphic rocks of suspected Valdez Group protolith (argillite and greywacke).  Includes biotite schist and granitoid gneiss.
PK Sheared greenstone, tuff, wacke, argillite, and chert of presumed Paleozoic or Mesozoic age.  Correlated with rocks of the Tarr Inlet suture zone (Brew and others, 19??); thus may belong to Chugach or Wrangellia terranes.
PMsv Moderately to highly deformed greenstone; minor argillite, chert, marble, diorite, serpentinite; of presumed Mesozoic or Paleozoic age.

ALEXANDER TERRANE (114O and 114P, west of the Denali/Duke fault system)

uTrT

Pillow basalt, basaltic sills, and calcareous argillite and siltstone of the Tats Group (Includes related strata in the Mount Henry Clay area that may in part be older).

PMgm

Paleozoic or Mesozoic greenstone and marble complex (114O).

Pma

Amphibole schist of probable mafic volcanic protolith (114O).

Pms

Undivided schist, gneiss, and marble of presumed Paleozoic age (114O).

SPs1

Undifferentiated Silurian to Mississippian (Pennsylvanian-Permian?) rocks.  Includes metamorphosed sandstone, shale, limestone, conglomerate, and minor intermediate to mafic tuff and flows.  Mainly west of the Tatshenshini and Tkope rivers.

SPs2

Undifferentiated metamorphosed siliciclastic and calcareous sedimentary rocks and greenstone, extensively hornfelsed in places.  East of the Tatshenshini and Tkope rivers.

IPs

Metamorphosed quartz-rich sandstone and siltstone and shale of known and suspected Ordovician age; interbedded with SPs2.

Oc

Mainly Ordovician limestone, thin bedded to massive, may contain thinly-bedded chert or calcareous siltstone.

Os

Early to Middle Ordovician shale, argillite, and cherty argillite.

COsb

Silty carbonate and phyllite with interlayered submarine basalt flows and sills of presumed Early Ordovician and Cambrian age.

WRANGELLIA, TAKU(?) or ALEXANDER TERRANES (Assignment Uncertain)

PTrv

Pillow basalt and related marble and sedimentary rocks of known and suspected Late Triassic age (correlated in part with the Nikolai Greenstone, McCarthy Formation, and Chitiztone and Nizina limestones of the Wrangellia terrane.

PMvs

Amphibolite, greenstone, minor greenschist, and rare metagreywacke and argillite of presumed Paleozoic or Mesozoic age.

NISLING TERRANE(?) (Assignment Uncertain)

Msm

Biotite schist, minor amphibole and granitoid gneiss and marble of Mesozoic or older age. 

PMgn

Undifferentiated gneissic rocks of presumed Paleozoic or Mesozoic age (114P).

Geological base and legend are derived from:

Campbell, R.B. and Dodds, C.J. (1983): Geology, Tatshenshini River Map Area (114P): Geological Survey of Canada, Open File 926, Scale, 1:125,000.

Campbell, R.B. and Dodds, C.J. (1983): Geology, Yakutat Map Area (114O): Geological Survey of Canada, Open File 927, Scale, 1:125,000.

Mihalynuk, M.G., Smith, M.T., MacIntyre, D.G., Timmerman, J., Deschenes, M. and Schiarizza, P. (1993): Yakutat Map Area, Northwestern British Columbia, (NTS 114O/9, 10, 14, 15 & 16); BC Ministry of Energy, Mines and Petroleum Resources, Open File 1993-12, 5 sheets.

Mihalynuk, M.G., Smith, M.T., MacIntyre, D.G., Deschenes, M. (1993): Tatshenshini Project, Northwestern British Columbia, (NTS 114P/11, 12, 13, 14; 114O/9, 10, 14, 15 & 16); Part B: Stratigraphic and Magmatic Setting of Mineral Occurrences; in Geological Fieldwork, 1992, BC Ministry of Energy, Mines and Petroleum Resources, Paper 1993-1, pages 189-202.

Mihalynuk, M.G., Smith, M.T., MacIntyre, D.G., Deschenes, M., Timmerman, J. and Schiarizza, P. (1993): Northwest Tatshenshini River Map Area, Northwestern British Columbia, (NTS 114P/11, 12, 13, & 14); BC Ministry of Energy, Mines and Petroleum Resources, Open File 1993-13, Sheet 1 of 6.

Smith, M.T., Mihalynuk, M.G. and MacIntyre, D.G. (1993): Tatshenshini Project, Northwestern British Columbia (114P/11, 12, 13, 14; 114O/9, 10, 14, 15, & 16), Part C: Deformation and Structural Styles; in Geological Fieldwork, 1992, BC Ministry of Energy, Mines and Petroleum Resources, Paper 1993-1, pages 203-216.

For more detailed information for this area refer to the British Columbia Ministry of Energy, Mines and Petroleum Resources; geochemical variable maps - B.C. RGS 18 (GSC OPEN FILE 1645); Assessment Report Index Map - 114P - TATSHENSHINI; bedrock geological mapping - Index of Bedrock Mapping, 1983; mineral and placer claim maps - contact the Mineral Titles Branch, Victoria

See TATSHENSHINI/YAKUTAT MAP AREA (114O-P) Summary Sheet for an overview of the map area and additional regional references.

Positions of all geological contacts are approximate. In the case of an apparent disagreement between an occurrence’s geological location on the map and its stratigraphic setting given in the MINFILE documentation, the latter should be given priority.