Geoscience BC's QUEST-Northwest Project is a multidisciplinary, integrated project designed to help focus mineral exploration in a highly prospective area of northwestern BC. The project's main activities include: two airborne magnetic surveys flown at line spacing of 250 metres, bedrock geological mapping and a geochemical program. The digital bedrock data set presents the field mapping results of the QUEST-Northwest Dease Lake Geoscience project - a partnership between Geoscience BC and the BC Geological Survey. The project completed regional scale bedrock geological mapping over a 1275 km2 area extending south west from the community of Dease Lake to the Tuya River, and coincides with the northwest corner of the QUEST-Northwest Block 1 airborne magnetic survey area (released through Geoscience BC in January).
The Dease Lake map sheet 104J/8 and the east half of Little Tuya River map sheet 104J/7 are underlain mainly by Paleozoic to Late Triassic sedimentary, volcanic and plutonic arc rocks of the Stikine Terrane, which locally host large Cu-Au porphyry deposits like Red Chris, Schaft Creek and Galore Creek. In the northeast part of the map these rocks are thrust imbricated with similar aged volcanic and sedimentary oceanic rocks of the Cache Creek Terrane along the north-dipping King Salmon Fault. Early to Middle Jurassic sedimentary rocks of the Takwahoni and Inklin formations of the Whitehorse Trough overlie the Stikine and Cache Creek terrane rocks respectively. Middle Jurassic granodiorite and an equi-dimensional Paleocene granite with associated molybdenum mineralization intrudes the Early Jurassic Takwahoni sedimentary rocks. Unconformably capping some of the highest peaks in the area are columnar basalts of the Miocene to Pliocene Tuya Formation. Preserved beneath these young basalts in the southwest corner of the map are lower Tertiary coal-bearing sediments of the Tanzilla Canyon Formation.
The map provides revised geology, geochemical analyses of alteration and mineralization and new isotopic dates for volcanic and plutonic rocks in the area which when integrated with regional exploration target models and the new airborne magnetic and geochemical data collected by Geoscience BC are expected to benefit the exploration community.