Preliminary Geology of the Gataga Mountain Area
BCMEMPR Open File 1996-03
Scale 1:50 000
View Open File (PDF, 4.27 MB)
Open File 1996-03 presents the geology and mineral occurrences of the Gataga Mountain area (94L/10, 11, 14, 15) in northeastern British Columbia. The geology map at 1:50 000 scale includes a legend, geological cross sections, and references as well as fossil identification, mineral occurrence, lithogeochemical analysis tables.
The oldest strata in the area are units of the Lower Cambrian Gog Group. The lower unit consists of siliciclastics and carbonates, including quartzite, quartz sandstone, siltstone, slate, limestone and dolostone; the upper unit of volcanic and volcaniclastic rocks including ash and lapilli tuff, agglomerate, basalt flows and flow breccias and volcanic wacke and siltstone. Lower to Middle Cambrian strata include Gog and younger rocks. The Middle Cambrian unit is mainly conglomerate with lesser siltstone, limestone and volcanics. The younger unit consists dominantly of siltstone, slaty siltstone, slate, and micaceous sandstone. Two units of Kechika Group are of Cambrian age; the older is dominated by siliciclastics, including slate, slaty siltstone, and micaceous sandstone; the younger contains mainly carbonates, including limestone, dolostone and dolomitic limestone. The Upper Cambrian to Lower Ordovician strata of the Kechika Group are mainly slate, calcareous slate with local limestone lenses. Road River Group strata include Middle to Late Ordovician recessive carbonaceous graptolitic slate to siltstone, cherty slate, argillite and chert; Lower Silurian to Middle Devonian rocks of the ‘Silurian Siltstone’ unit, and undivided rocks. The Silurian Siltstone consists of mostly of siltstone to dolomitic siltstone, slate and silty slate. Earn Group rocks are of Middle Devonian to Early Mississippian age. Carbonaceous slate, siltstone, cherty slate, cherty argillite and chert predominate.
The fabric of the geology trends northwest due to a series of moderate to very tight overturned folds and northwest trending thrust faults. The thrusts are northeast-verging and dip relatively steeply toward the southwest. Structural detachment is most important in the Kechika and Ordovician Road River shales. Earn lithologies are also relatively incompetent. Major thrust carry Cambrian or uppermost Proterozoic strata in their hanging immediate wall, and there are several major thrusts. Very large, northeasterly overturned folds can be recognized.
The Kechika Basin is part of a metallogenic province characterized by sedimentary exhalative lead-zinc-barite deposits. Devono-Mississippian Earn Group rocks have the highest mineral potential in the area and many stratiform barite occurrences were located. One occurrence was within the Ordovician Road River Group. Rocks in the map area are a northward extension of the structural panel that hosts the Driftpile Creek and other stratiform barite and barite-sulphide deposits. Other occurrences of interest include a zone of lead-rich veinlets in Earn rocks and zinc and barite-rich crosscutting breccia in chert and limestone of the uppermost Road River Group. There are also quartz vein occurrences in carbonates containing copper sulphides or tetrahedrite.
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