P. Schiarizza


The Andrea Creek map area is located in northern British Columbia, about 100 km east of Dease Lake. It covers about 200 square kilometres and encompasses the transition between the Stikine Ranges of the Cassiar Mountains to the north and the Spatsizi Plateau to the south. Open File 2011-07 presents a 1:25 000-scale geologic map of this area based on fieldwork conducted in 2010. The map features new subdivisions of the Permo-Triassic Kutcho assemblage, a heterogeneous package of schists derived from felsic and mafic volcanic and volcaniclastic rocks and associated felsic and mafic intrusions, which hosts the Kutcho Creek Cu-Zn volcanogenic massive sulphide occurrence (MINFILE 104I 060). The Kutcho assemblage is part of the King Salmon allochthon, which also includes a structurally underlying unit of metabasalt and serpentinite assigned to the Cache Creek Complex, and a Triassic-Jurassic metasedimentary succession that overlies the Kutcho assemblage across an erosional unconformity. The latter succession includes a local conglomerate unit containing clasts derived from the Kutcho assemblage, and overlying limestone, slate, siltstone and sandstone correlated with the regionally extensive Late Triassic Sinwa and Early to Middle Jurassic Inklin formations. The allochthon is bounded to the south by the north-dipping King Salmon thrust fault, and to the north by the Nahlin fault. Jurassic chert-pebble conglomerate of the Bowser Lake Group occurs in the footwall of the King Salmon fault, and serpentinized ultramafic rocks of the Cache Creek complex crop out on the north side of the Nahlin fault. The northwest-striking Kutcho fault truncates the King Salmon allochthon near the northeast edge of the map area, and juxtaposes it against undated plutonic rocks, mainly granodiorite and quartz diorite, which are part of the Quesnel terrane.

Operating funds for the 2010 mapping program were provided by the BC Geological Survey, a private-public partnership agreement with Kutcho Copper Corporation, the Geological Survey of Canada (EDGES component of the GEM program) and a partnership agreement with the University of Victoria.

Details and descriptions of the geologic units and structures within this map area can be found in:
Schiarizza, P. (2011): Geology of the Kutcho assemblage between Kutcho Creek and the Tucho River, northern British Columbia (NTS 104I/01); in Geological Fieldwork 2010, British Columbia Ministry of Energy and Mines,Paper 2011-1, pages 99-117