ch2 (档265 mb).ppt

SUDBURY MINING CAMP To date, the Sudbury mining camp has produced in excess of 16 billion pounds of nickel, 15 billion pounds of copper, 85 million ounces of silver, 17 million ounces of platinum, and 3 million ounces of gold and remains, to this day, Canada’s principal producer of platinum. Currently, there are 35 producing mines in the Sudbury Camp. GEOLOGY OF THE SUDBURY REGION The Sudbury region is dominated by a large 60 km long by 30 km wide elliptical depression known as the Sudbury Structure which lies at the junction of three unique geological-structural provinces: the granitic gneissic basement rocks of the Archean Superior Province to the north, the supracrustal metasediments and metavolcanics of the Early-Proterozoic Southern Province to the south, and the Middle-Proterozoic Grenville Front Tectonic Zone. GEOLOGY OF THE SUDBURY STRUCTURE The Sudbury Structure constitutes the largest known concentrations of nickel-copper-PGE bearing sulfide minerals in the world. Due to its economic importance, the structure is one of the most intensively studied and documented regions of the Canadian Shield. Stratigraphically, from top to bottom, the Sudbury Structure consists of the Whitewater Group of sediments, the underlying Sudbury Igneous Complex (“SIC”), and brecciated footwall rocks surrounding the SIC. The Whitewater Group Infilling the central depression of the Sudbury Structure are the Whitewater Group sediments that consist of, from top to bottom: the Chelmsford Formation greywacke, the Onwatin Formation manganese-rich slate, and the Onaping Formation volcaniclastic/breccia sequence. The Sudbury Igneous Complex Underlying the Whitewater Group is the Sudbury Igneous Complex (“SIC”). The SIC consists of a lower zone of augite-bearing norite; a thin middle layer (Transition Zone) consisting of norite grading upwards into quartz gabbro; and an upper zone of micropegmatite/granophyre. At the base of the lower zone is a discontinuous zone o