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TitlePreliminary interpretations of detailed mapping in the Chilcotin Group, Chasm Provincial Park, British Columbia
AuthorFarrell, R -E; Simpson, K A; Andrews, G D M; Russell, J K; Anderson, R G
SourceGeological Survey of Canada, Current Research (Online) no. 2008-13, 2008, 13 pages,
PublisherNatural Resources Canada
Mediaon-line; digital
File formatpdf (Adobe Acrobat Reader)
ProvinceBritish Columbia
AreaChasm Provincial Park
Lat/Long WENS-121.5000 -121.3333 51.2500 51.1667
Subjectsstratigraphy; bedrock geology; Eocene; Miocene; igneous rocks; sedimentary rocks; sedimentary facies; basalts; lava flows; breccias; sandstones; clastics; clastic facies; pillow breccias; pillow lavas; emplacement; Chilcotin Group; Cache Creek Group; Kamloops Group; Deadman River Formation; Paleozoic; Permian; Cenozoic
Illustrationslocation maps; photographs; stratigraphic sections; logs
ProgramSouthern Cordillera TGI-3, Targeted Geoscience Initiative (TGI-3), 2005-2010
Released2008 06 04
AbstractWithin Chasm Provincial Park, the Chilcotin Group basalt overlies rocks of the Permian Cache Creek Group, the Eocene Kamloops Group, and the Miocene Deadman River Formation. Detailed mapping of the Chilcotin Group has identifi ed a variety of subaqueous and subaerial volcanic and sedimentary facies. Within the coherent rocks, three distinct facies have been described, 1) plagioclase-phyric basalt (Pp), 2) aphyric columnar-jointed basalt (Ac), and 3) aphyric massive basalt (Am). All coherent facies are interpreted as subaerial, fl at-lying basalt lavas. Clastic facies include pillow-fragment breccia (Pf) and sandstone-to-breccia (Sb). The presence of intact pillows, pillow fragments, and hyaloclastite within the pillow-fragment breccia facies provides evidence for a local subaqueous environment. The sandstone-to-breccia units occur between the coherent lava units and are interpreted as paleosols that represent volcanic hiatuses during emplacement of the Chilcotin Group lavas.