Nickel Sulfide Ores and Impact Melts

Origin of the Sudbury Igneous Complex

Peter C. Lightfoot

• Publisher: Elsevier
• Year: 2016
• ISBN:
  9780128041055
• Topic: Physical Sciences
• Subtopic: Geology & Earth Sciences

Nickel Sulfide Ores and Impact Melts: Origin of the Sudbury Igneous Complex presents a current state of understanding on the geology and ore deposits of the Sudbury Igneous Complex in Ontario, Canada. As the first complete reference on the subject, this book explores the linkage between the processes of meteorite impact, melt sheet formation, differentiation, sulfide immiscibility and metal collection, and the localization of ores by magmatic and post-magmatic processes.

The discovery of new ore deposits requires industry and government scientists and academic scholars to have access to the latest understanding of ore formation process models that link to the mineralization of their host rocks. The ore deposits at Sudbury are one of the world's largest ore systems, representing a classic case study that brings together very diverse datasets and ways of thinking.

This book is designed to emphasize concepts that can be applied across a broad range of ore deposit types beyond Sudbury and nickel deposit geology. It is an essential resource for exploration geologists, university researchers, and government scientists, and can be used in rock and mineral analysis, remote sensing, and geophysical applications.

• Provides the only reference book to focus entirely on the Sudbury Igneous Complex
• Brings together an understanding of ore deposit and impact melts as a basis for future exploration
• Authored by a leading expert on the geology of the Sudbury Igneous Complex with 35 years of experience working on nickel sulfide ore deposits

Chapter 1

Sudbury – an introduction to the ore deposits and the impact structure

Introduction to Sudbury

Three facts about the Sudbury Structure place it among the crown jewels of planetary geoscience: (1) It is one of the largest, oldest, and best-preserved impact structures on planet Earth; (2) it was and remains the birthplace of important geoscience controversies in igneous petrogenesis, ore deposit geology, and impact cratering; and (3) it is home to Canada’s largest mining camp with more than 100 years of mining activity on deposits of high-grade nickel sulfide ores. Quite how these three themes and the many strands of science and discovery that underpin them have evolved into a holistic understanding of the geology of Sudbury make it a classic study in Earth Sciences.

Wagner’s views on continental drift, and the theory of plate tectonics were at the root of a revolution in Earth Sciences in the 20th century (Wegener, 1929), but the sudden and catastrophic events that change the planet in seconds to years rather than millions of years are at the crux of a shift in geoscience emphasis away from progressive (albeit rapid) change to sudden and profound shifts in the configuration of planet Earth. The Sudbury Structure is a case study in rapid change. Its formation was triggered by an impact event that lasted a fraction of a second followed by a crustal readjustment period likely lasting much less than 250,000 years. Exploration and mining activities over a period of more than 100 years in the Anthropocene underpin our current three-dimensional understanding of the geology of the shallow part of the Sudbury Structure above ∼3 km depth. The path to our current understanding has triggered many epiphanies and quite a few global revolutions in the Earth Sciences. Living in the footprint of an astrobleme, one has a privileged opportunity to understand the complex geology as an outcome of a catastrophic event that happened on a short time scale relative to the slow motion of plate tectonics and mantle plumes. This book is written to explain the importance of geoscience, exploration, and discovery as it relates to not just ore deposits, but the further understanding of the Sudbury impact structure.

The City of Sudbury, located in Northeastern Ontario, Canada, is one of the world’s principal sites of global nickel production; it is a city with a mineral industry that has evolved through almost 130 years. Since the discovery of the ore deposits, over 11.1 million metric tons of nickel and 10.8 million metric tons of copper together with by-products of cobalt, silver, gold, and platinum group elements (PGE) have been mined from the ore deposits (modified after Mudd, 2010). This wealth has been and continues to be generated from seven major mine complexes and 21 smaller ore deposits around the outer margin of the SIC which comprises part of the Sudbury Structure; the principal mines are owned and operated by international mining companies (Vale, Glencore, KGHM) and smaller mining companies (eg, Wallbridge). The high-grade ore deposits of the SIC are among the largest known historically mined and future resources of Ni–Cu–PGE sulfides, and comprise the foundation of the economic wealth of one of the largest mining camps in the world. The economic wealth generated at Sudbury in terms of just nickel and copper value at current metal prices (± March 2015 nickel price) is close to 215 billion US dollars. The Sudbury Nickel Camp has underpinned the growth of the economy of Canada and Ontario, inspired contributions to the science of magmatic ore deposit geology (Naldrett, 2004), triggered the development of exploration technologies such as airborne geophysics and down-hole electromagnetic geophysical tools (Polzer, 2000; King, 2007), and provided a foundation for the development of mining technologies to handle the challenges of extraction of mineral from deep mines, the process technology for sulfide ores, and the foundation for the future growth of a global service center in the City of Sudbury in Northeastern Ontario.

The Sudbury Nickel Camp is second in the world in terms of contained Ni in sulfide deposit (contained metal in historic production and unmined reserves and resources), behind that of the Noril...