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.[1] 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.[2] 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.[3]

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.[8] The bolide impact created a crater 200 to 250 km across and melted the pre-existing rock, which partially filled in the crater.[8] Today, the SIC is approximately 3 km thick, and has an elliptical footprint of approximately 60 km by 27 km.[8]

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.[9] 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).[9][8] Pre-existing weaknesses in the footwall play a crucial role in the distribution of these sulfide-rich structures.[9] This results in a spatial association between the sulfide-rich ore deposit locations and the lithological contact between the footwall and the Sudbury Breccia.[9] The contact between the SIC and the footwall is marked by "broad haloes of metalliferous hydrous silicate minerals",[9] thought to be created by the early process of magmatic-hydrothermal fluid alteration and the late process of metamorphic fluid alteration.[9]

Geology of the Creighton Mine

The Creighton Mine property is home to the South Range geologic unit, which contains the main orebody of the mine.[9] The major mineralization occurs as platinum-group mineral (PGM)-rich intrusions within the footwall.[10] Sulfide-rich base metal intrusions also contribute to the mine's mineralization.[10] The amphibole within the ore body shifts from ferro-hornblende to ferro-tschermakite amphibole.[9] This, along with the calcium and tantalum variations and an age of titanite of 1.616 billion years, has been interpreted to reflect an "increasing temperature-pressure gradient towards shear zones that were active during the Mazatzalian orogeny".[9] It is also believed that the sulfides of this deposit were re-mobilized during this event.

Ore minerals

86% of the precious metal mineralogy at the mine consists of PGE sulfarsenides, 9% is sperrylite, 5% is michenerite, and 0.1% is electrum.[10] These minerals are generally found hosted by pentlandite and pyrrhotite.[10] Michenerite, however, is found near or hosted by silicate minerals.[10] Euhedral zoning with an " irarsite (IrAsS) core, an outer layer of hollingworthite (RhAsS), and a PGE-rich Ni cobaltite rim (CoAsS)"[10] is common of the PGE sulfarsenides found at the mine.[10] Osmium bearing rhenium sulfides also have documented occurrences at Creighton Mine.[10]

place	Greater Sudbury
state/province	Ontario
country	Canada
pushpin map	CAN ON Greater Sudbury#Ontario#Canada
pushpin label	Creighton Mine
mapframe	yes
mapframe-zoom	13
mapframe-wikidata	yes
coordinates	46.46389°N, -81.17472°W
pushpin map caption	Location of the mine within Ontario
subdivision type	Province
products	Nickel, Copper, Platinum, Palladium, Gold, Silver
type	Underground, originally open pit
opening year	1901
owner	Vale Limited
official website	vale.com

History

Discovery and development

The Creighton settlement

Geology

Formation of the Sudbury Igneous Complex

Geology of the Creighton Mine

Ore minerals

Production

Mining methods

Production levels

Seismic events

Ground control

SNOLAB

Creighton deepening project

Environmental projects and concerns

Diesel to electric

Groundwater treatment

Underground greenhouse

See also

References