Major lithologies and alteration of the Ajax East orebody, a sub-alkalic copper-gold porphyry deposit, Kamloops, south-central British Columbia
Published:January 01, 1994
K.V. Ross, K.M. Dawson, C.I. Godwin, L. Bond, 1994. "Major lithologies and alteration of the Ajax East orebody, a sub-alkalic copper-gold porphyry deposit, Kamloops, south-central 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 Ajax East pit, in the Afton mine district, on the southwestern side of the sub-alkalic Iron Mask batholith, was developed on copper-gold mineralization located 600 m east of the Ajax West pit. Porphyry-style mineralization, mainly pyrite and chalcopyrite, is located at the intersection of two dioritic phases of the Iron Mask pluton.
Pit mapping at 1:750 scale and logging of representative drill core sections in 1992 resulted in the recognition of nine major lithologies and a revised chronological order: (I) Nicola volcanics. (2) picrite, (3) hybrid diorite, (4) pegmatitic hybrid diorite, (5) Sugarloaf diorite, (6) pyroxene gabbro, (7) monzonite dykes, (8) syenite dyke and (9) quartz-eye latite dykes.
Intense albitization in the Sugarloaf diorite is related both spatially and temporally to mineralization. Potassic alteration is most intensely developed in the relatively mafic hybrid diorite and Nicola volcanic units and is also related to mineralization.
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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