Economic aspects of Terrestrial Impact Structures

English Abstract:

Impact structures on Earth have played a significant role in the creation and preservation of economic deposits, including metal ores and hydrocarbons. In Canada, well-known structures include Sudbury, renowned for its world-class Cu-Ni sulfides and associated platinum group element deposits; Manicouagan for facilitating a ~6000 MW hydroelectric generating capability; and Steen River for multizone oil and gas potential, along with numerous buried craters within the Williston Basin (e.g., Viewfield, Sakatchewan). Key processes associated with economic deposit development include (1) fusion of crustal rocks to create a melt body that fractionates and so concentrates immiscible and/or dense phases that are rich in metals; (2) creation of fractured, permeable rock volumes to act as reservoirs for hydrocarbons; (3) creation of basins that can preferentially accumulate hydrocarbons; (4) formation of traps and seals through generation of impact melt sheets and/or impermeable frictionally-fused fault systems; (5) creation of hot rock-water hydrothermal systems that can precipitate economic volumes of metals (e.g., within the Onaping Formation at Sudbury). Critical to exploiting the economic potential of impact craters is to understand their internal structure, especially in terms of syn- to post-impact tectonics. Many of the larger surviving craters on Earth have been modified since their formation, making the distinction between impact-generated features and subsequent overprinting effects challenging. This presentation will review examples of terrestrial impact structures exhibiting economic potential; both proven and pending. Key structural controls will be reviewed as a guide to exploration rationale for both metals and hydrocarbons, as well as other uses (e.g., waste storage).