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Geology of the central part of the Callaghan Creek pendant, Southwestern B.C.

University of British Columbia

Callaghan Creek pendant, about 85 k north of Vancouver, B.C., is one of many northwesterly trending volcanic and volcanic-sedimentary pendants within the southern part of the Coast Plutonic complex. Rocks within this pendant have been correlated tentatively with the Gambier Group on the basis of lithologic similarities with type sections of the Gambier rocks to the south. A crystal tuff unit in the Callaghan Creek sequence has been cut by what are thought to be genetically related hornblendite dykes for which a single K-Ar date on hornblende of 124 ± 4 m.y. was obtained. Five major rock units were recognized in the Callaghan Creek pendant. Compositions range from a rhyodacite to more abundant andesites. Generally, these rock units dip steeply to the east, strike northerly to northwesterly, and appear to form a homoclinal succession with tops to the east. The envisaged depositional environment is of explosive volcanism in an arc environment characterized by calc-alkaline volcanism which probably extended along the length of the Coast Plutonic complex during Jurassic and Early Cretaceous time. Plutonic rocks, ranging in composition from quartz diorite to granodiorite and diorite, surround the Callaghan Creek pendant. Pleistocene to Tertiary rocks overlie and locally intrude the pendant and plutonic rocks. Seven mineral occurrences were recognized in the mapped area of the Callaghan Creek pendant, three of which, the Manifold, Warman and Discovery zones, are in production by Northair Mines Limited (N.P.L.). Minor production has come from three of the more southerly occurrences; the Silver Tunnel, Millsite and Tedi Pit zones of Van Silver Explorations Limited (now in receivership). The Manifold, Warman and Discovery zones of Northair Mines and the Tedi Pit mineral occurrences of Van Silver Explorations show various structural and textural features indicating that a significant portion of the sulphides may have concentrated prior to regional metamorphism (greenschist facies) and emplacement of Coast Plutonic rocks. An apparent stratigraphic control, association with dacitic volcanics, local intercalations with exhalites (carbonate and cherte) combined with textural data and systematic variations in assay values suggest that these occurrences are volcanogenic in origin but have suffered considerable mobilization during subsequent metamorphism.

Text

2010-03-05

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http://hdl.handle.net/2429/21538

Geological Sciences

University of British Columbia

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