Regional Geology of The Quesnell Terrane, Southern British Columbia
1994. "Regional Geology of The Quesnell Terrane, Southern British Columbia", Selected Mineral Deposits of British Columbia, Canada: I. Porphyry Ore Deposits Of Southern British Columbia II. Mineral Deposits Of Northern Vancouver Island, C.R. Stanley, W.J. McMillan, Andre Panteleyev
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The Copper Mountain and Afton/Ajax alkalic porphyry copper-gold camps and Highland Valley calc-alkalic porphyry copper-moybdenum camp occur within Quesnellia, a northerly trending Mesozoic tectonostratigraphic terrane in central British Columbia. This terrane consists of a volcanic arc and overlying set of sedimentary packages that developed on a deformed oceanic sediment/volcanic complex (Harper Ranch and Okanagan subterranes) and was located somewhere offshore of North America during the early Mesozoic (Monger et al., 1992). The principal unit making up Quesnellia in southern British Columbia is the Late Triassic Nicola Group, a predominantly subaqueous island arc assemblage composed of volcanic and sedimentary rocks that have been intruded by early Jurassic alkalic, calc-alkalic and zoned mafic (Alaska-type) plutons and batholiths (Preto, 1977, 1979).
The Nicola Group occurs as a north-trending belt approximately 25 km wide approximately 7.5 km thick, extending from the U.S. border to north ofKamloops Lake (Schau, 1968; Preto, 1972; Preto, 1979; Mortimer, 1987). It is composed predominantly of augite-phyric andesites and intermediate-to-felsic pyroclastic rocks with subordinate amounts of greywacke, argillite and reefal limestone. The Nicola Group is broken into three blocks by two sub-parallel fault systems (the eastern one defined by the Boundary Fault, Princeton Graben, Summers Creek, Allison Lake and Quilchena Faults, Nicola Horst, Cherry Creek Fault and Kamloops Graben; the western one defined by the Coquihalla, Murray Lake, Fig Lake, Lornex, Guichon Creek and Deadman River Faults; Monger, 1989b; Monger and McMillan, 1989). The eastern fault system defines a zig-zag pattern of fault intersections and forms several 'rhombochasmic' horst and
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Selected Mineral Deposits of British Columbia, Canada: I. Porphyry Ore Deposits Of Southern British Columbia II. Mineral Deposits Of Northern Vancouver Island
km 0 Depart from the Delta Town and Country Inn. Zero your odometer at the Inn. Turn right onto River Road (Highway # 17). Cross the overpass and take the freeway on-ramp onto Highway # 99 south toward Seattle.
km 8 Take Exit # 20 (Highway # 10) east toward Langley and Hope. The road climbs a hill from the Fraser River delta late Holocene (< 8000 years before present) Salish Sediments (shoreline sand and clayey silt; river gravel, sand, silt and clay; peat bogs and swamps) through Pleistocene Vashon Drift (Fraser Glaciation) and pre-Vashon deposits from the Olympia and Highbury non-glacial intervals and the Semiahmoo and Westlynn Glaciations (tills, glaciofluvial, glaciolacustrine, glaciomarine and deltaic sediments), onto early Holocene (10,000 to 8000 years before present) glacial retreat and melt-out deposits of the Sumas Drift, Ft. Langley Formation and Capilano Sediments (Armstrong, 1990).
Lacustrine (principally oxbow lake) environments of these units near Maple Ridge, British Columbia are the only good local source of fire clay. These are valuable deposits because of their low Ca concentrations, relative to Na and K, and true clay mineralogy. Other clay deposits within British Columbia are predominantly glacial, and thus generally contain only un-weathered clay-sized particles instead of clay minerals. Furthermore, the overall quartz diorite composition of the country rocks that underlie the Fraser River drainage basin generally results in Ca-rich bricks which form a generally undesirable white precipitate over time.
km 32 Highway# 10 turns left toward Fort Langley.
km 36 Highway # 10 turns right.
km39 Turn right onto Highway # 1 (the Trans-Canada Freeway) toward Hope. This freeway crosses the ‘Lower Mainland’, the agriculturally important Fraser River delta (here consisting predominantly of Ft. Langley Formation glacial and deltaic sediments; Armstrong, 1990), which narrows to a significant defile at the town of Hope.
Km 51 In clear weather, Mt. Baker (3285 m), a Cascade andesite stratovolcano is in view directly ahead. This most-northerly United States Cascade volcano last erupted in 1843 during the waning stages of its third cycle of volcanism (approximately 50, 31–34 and 17 million years ago). It is now considered to be dormant, although minor fumarolic activity has occurred within and immediately adjacent to its 90 m wide summit crater since 1975 (Armstrong, 1990). Mt. Baker is considered to be a ‘coherent’ Cascade volcano (McBimey, 1968), meaning that it is dominated by relatively quiescent andesitic lava and phreatic ash eruptions, without