Stratigraphy and sedimentology, Horsethief Creek Formation, northern Dogtooth Mountains, British Columbia
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AbstractIn the northern Dogtooth Mountains, the exposed Precambrian rocks are represented by the Horsethief Creek Formation, 700o+ ft. thick, contorted and faulted, consisting of four members in the following upward sequence: Feldspathic Grit Member, Lower Slate Member, Limestone Member, and Upper Shale Member. The Feldspathic Grit Member is interpreted as mainly delta-front elastic deposits and is recognized over the total study area. Available evidence suggests the sediments were derived from the east. The Lower Slate Member is mainly slate, interpreted as marine, with upper parts probably equivalent in age to parts of the Limestone Member. The Limestone Member consists of carbonate and elastic rocks varying from supratidal to probably "deeper" water deposits. Slumped units and close lateral relationship of shallow and "deeper" water deposits suggest minor penecontemporaneous tectonism. The Upper Shale Member is mainly dolomitic elastic rocks, and is recognizable with certainty only in eastern parts of the area. At Rogers Pass, and in areas where metamorphic minerals higher in grade than chlorite occur, identification of the members is hazardous. Locally, garnetiferous rocks occur, but most of the area contains rocks probably representing the biotite zone. The sequence of members is recognizable in homotaxial rocks throughout the southern Canadian Cordillera. Local absence of this sequence may be due to facies changes, and/or erosion at the sub-Cambrian unconformity. The base of the Cambrian Hamill Group is sharply defined in some places and apparently gradational in others.
Bibliography: p. 92-97.