Geoscience Map 2011-01: Geology, Geochronology, Lithogeochemistry and Metamorphism of the Holberg-Winter Harbour Area, Northern Vancouver Island (Parts of NTS 092L/05, 12, 13; 102I/08, 09 & 16) 1:50 000 scale
View Geoscience Map 2011-1 (PDF, 6.8 MB)
Geoscience Map 2011-1 (1:50 000-scale) is the first in a series of five new geological maps (Geoscience Maps 2011-1 to 2011-5) of northern Vancouver Island which together provide a revised Early Mesozoic stratigraphic framework and Mesozoic-Tertiary plutonic history for southern Wrangellia. Geoscience Map 2011-1 describes the geology, geochronology, lithogeochemistry and metamorphism of the Holberg - Winter Harbour area (parts of NTS 092L/05, 12, 13; 102I/08, 09 and 16). The map area is underlain by a folded and faulted sequence of Late Triassic to Middle Jurassic volcanic and sedimentary rocks of the Vancouver and Bonanza groups intruded by granitoids of the Early to Middle Jurassic Island Plutonic Suite. The deformed Triassic-Jurassic rocks are unconformably overlain by Cretaceous marine clastics and cut locally by Tertiary dikes and minor intrusions. Middle Jurassic intrusions of the Island Plutonic Suite (e.g. Hushamu Creek and Goodspeed River plutons) are spatially and genetically associated with important calc-alkaline Cu-Au-Mo porphyry-style mineralization similar to the deposit at the former Island Copper mine, as well as coeval high-sulphidation, base- and precious-metal epithermal prospects hosted by rhyolitic flows and pyroclastic rocks in the Pemberton Hills – Mount McIntosh area. Major northwesterly-trending structures along Holberg Inlet and the Stranby River, the Holberg-Stranby fault system, separate well-mineralized, Middle Jurassic intrusions and the broadly coeval Holberg volcanic unit of the Bonanza Group from their Early Jurassic counterparts to the west. Radical changes in lowermost Jurassic stratigraphy are also evident across this structural corridor: a thick, predominantly subaerial, volcanic-volcaniclastic sequence (Le Mare Lake volcanic unit) west of the Holberg-Stranby faults largely correlates with a more condensed succession of intercalated, marine sedimentary and volcaniclastic strata (Nahwitti River siltstone-wacke unit) east and north of the fault zone. Regional metamorphism is generally characterized by very low-grade mineral assemblages (prehnite-pumpellyite to zeolite facies) except in the vicinity of faults and intrusive contacts where the rocks may reach upper greenschist to amphibolite grade, respectively.
All publications of the BC Geological Survey are available digitally, free of charge, from this website.
For questions or more information on geology and minerals in British Columbia contact BCGS Mailbox or call toll free (B.C. residents only).