The Sudbury Basin and Nickel Mines Douglas Vance, Department of Geosciences, East Tennessee State University Abstract The Sudbury Basin is located in Ontario just north of Lake Huron. The basin was created by an almost two billion year old meteorite impact that also caused impact volcanism. The magma that partially filled the basin is rich in metal ores. The basin remained hidden until the late 1800’s but was discovered because of the mass erosion over the millions of years and the orogenies that distorted the appearance of the crater impact. The first settlers on the Canadian Pacific Railroad discovered copper and nickel ores around the border of the basin in Soon after, people started moving in and working the mine rich land. Over the years, Sudbury grew to become an important part of Canada’s economic system. Now one of the world leaders in nickel production, a company called Vale has guaranteed mining in Sudbury for the next few decades as well as helped to reduce the damage done to the environment by acid rain. Overall, the Sudbury Basin, also known as the Sudbury Astrobleme, will be a focus of study and mining for a very long time. Introduction Sudbury was founded in 1883 to serve as a simple railroad town for the Canadian Pacific Railway. It was built on the banks of Ramsey Lake which is located to the north of Lake Huron and the Georgian Bay. The first patent to mine was issued to Thomas and William Murray in The International Nickel Company and the United States created a strong trade for nickel in the late early 1900’s. The cities booms and busts were directly related to wars involving North America. Pollution became an issue because acid rain was devastating the region by blackening rocks and killing vegetation. The smelting process separates sulfur from the ores and it combines with oxygen to form sulfur dioxide. This is then released into the atmosphere. When the sulfur dioxide combines with water it forms sulfuric acid which in turn falls to the ground as acid rain. In 1972 INCO decided to build a superstack (Figure 1) about 1250 feet tall to reduce the impact of acid rain on the region. Formation of the Basin 1.85 billion years ago a 4 to 10 km diameter meteorite struck the area Large amounts of rock were thrown into the air that partially liquefied as a matrix and fell back to the ground as fallback breccia (Figure 2) The impact weakened the crust allowing magma partially filled the basin The magma differentiated into a nickel rich norite layer and basic micropegmatite layers The basin was then filled in by shallow marine sediments that lithified into slate and sandstone Shatter cones are rocks that show the shock waves that resulted from the impact and are scattered around the edge of the basin (Figure 3) Figure 4 Sudbury Basin structure and cross section Deformation of the Basin The Penokean Orogeny took place shortly after the impact event It caused south to north compression of the basin This orogeny is also responsible for the sedimentary rocks in the area outside of the Whitewater Group because of the formation of the Huronian ocean basin The Grenville Orogeny about 1 billion years ago caused southeast to the northwest compression which gave the basin its current shape Erosion would take over as no real depositional environments would affect the area until the Quaternary ice age Another meteorite struck the east edge of the basin about 37 million years ago This deformed the eastern edge and created Lake Wanapitei Figure 4 shows the current structure of the Sudbury Basin Economic Impact Sudbury produced about 75% of the world’s nickel in the 1950’s By the 1980’s Sudbury was only producing about 20% of the world’s nickel Today mining employs about 6,000 people in Sudbury INCO was purchased by Vale in 2006 for 18 billion U.S. dollars INCO at that time was the world’s second largest nickel producer behind a Russian company called Norilsk Nickel Vale now employs 4,000 workers, runs 6 mines, 1 mill, and a smelter One of the largest mining operations in the world A new mine called Totten Mine will be the first in 40 years (Figure 5) Opens in 2016 Will employ 200 full time workers and produce 2,000 tons of nickel, copper, and other metals every day for the next 20 years Figure 5 Totten Mine at Copper Cliff Discussion The Sudbury Basin is one of the most interesting geologic areas I have researched. The Sudbury nickel deposits have beneath the surface for almost two billion years and have only been explored and exploited for the past 100 years. This area has tested the scientific method over and over due to its complex structure. The impact theory is now confirmed due to the strong ties with other obvious impact structures such as breccia and shatter cones. The deformation of the basin during the Grenville Orogeny is also evident due to the compression and location of Grenvillian aged rocks. This process is interesting because the effects of the orogeny can be seen in the Appalachians of the United States. Finally, the history and economics of the city are the clear indication of how important this location is. The nickel mines have created Greater Sudbury and will continue to push it into the future. Conclusion Sudbury started as a simple railroad town in 1883 and mining began a year later when a mining patent was issued to Thomas and William Murray. The United States created strong ties with INCO in the early 1900’s which would decide the ups and downs for Sudbury through the cold war. Pollution issues were addressed as INCO built the superstack in 1972 and regulations were set in place to reduce acid rain. The basin was formed by a meteorite impact 1.85 billion years ago. The impact caused an extrusive lopolith. The magma lithified into a nickel and copper rich norite layer and a micropegmatite layer. The basin was crushed and reshaped by the Penokean and Grenville Orogenies to give the basin its current appearance. Vale is now Sudbury’s leading mining company and with their new Totten mine opening in 2016, mining will continue to power the cities economy for at least the next 20 years. Figure 1 INCO Superstack Figure 2 Sudbury Breccia Figure 3 Shatter Cones Micropegmatite and Norite Slate and Sandstone Granite and Gneiss