Creighton Mine
Creighton Mine is an underground nickel, copper, and platinum-group elements (PGE) mine. It is presently owned and operated by Vale Limited (formerly known as INCO) in the city of Greater Sudbury, Ontario, Canada. Open pit mining began in 1901, and underground mining began in 1906. The mine is situated in the Sudbury Igneous Complex (SIC) in its South Range geologic unit. The mine is the source of many excavation-related seismic events, such as earthquakes and rock burst events. It is home to SNOLAB, and is currently the deepest nickel mine in Canada. Expansion projects to deepen the Creighton Mine are currently underway. History Discovery and development The deposits at Creighton mine were the first mineralized deposits discovered in the Sudbury Igneous Complex (SIC) mining camp. They were discovered by Albert Salter in 1856 due to deflections in his compass readings. Production at Creighton Mine began in 1901 under the Canadian Copper Company, and later the International Nickel Company (INCO). The mine was an open-pit mine from 1901 to 1908, and was transitioned to an underground mine in 1906. In 1969, the 7138-foot No. 9 shaft was completed, making it the deepest continuous mine shaft in the Western Hemisphere. Brazil's Vale announced a $19.4 billion takeover of INCO, which was approved in 2007. The company was known as Vale S.A. (Vale) from 2009 onwards. The Creighton settlement Creighton Mine employed 94 men in 1902, and built accommodations for the men and their families. In 1903, school classes and religious services were being held in one of the company cabins for the miner's families. As the workforce at the mine increased, the company constructed more single family homes with running water and electricity. As development continued, the company began to include rent, hydro, and employees club deductions on the company pay cheques. In 1986, INCO announced that the company would be "getting out of the landlord business" due to the expense of maintaining the settlement to modern standards. The community of Creighton was closed on June 30, 1988. Geology The Creighton Mine lies within the Sudbury Igneous Complex. Formation of the Sudbury Igneous Complex The Sudbury Igneous Complex (SIC) is an impact melt structure, formed by the collision of a meteor 1.85 billion years ago. The bolide impact created a crater 200 to 250 km across and melted the pre-existing rock, which partially filled in the crater. Today, the SIC is approximately 3 km thick, and has an elliptical footprint of approximately 60 km by 27 km. An important geological unit within the SIC is the Sudbury Breccia, which is an impactite interpreted to have been formed during the impact crater modification or excavation. Copper, nickel, and PGE rich sulfides settled to the base of the molten Sudbury Breccia, and formed veins and stockworks of mineralization in the footwall (the non-igneous rocks underlying the SIC). Pre-existing weaknesses in the footwall play a crucial role in the distribution of these sulfide-rich structures. This results in a spatial association between the sulfide-rich ore deposit