The Neoarchean, a turning point for geodynamic and magmatic processes within the Superior craton?

Abstract

The Neoarchean is generally considered to have been the final era of major crust formation and may have been characterized by the onset of modern plate tectonics. The Neoarchean may also have been the time interval during which subduction processes prevailed and became global. Evidence from individual cratons around the world suggests that this transition in geodynamic processes may have included diachronous and episodic major changes (i.e., turning points) and a more gradual evolution at the global scale, possibly largely driven by the secular cooling of the mantle and increasing stability of the lithosphere. The Superior craton, Canada, is the largest and best-preserved Archean craton in the world, making it an ideal location in which to investigate the occurrence (or absence) of turning points in the Neoarchean. This contribution examines the changes in geodynamic and magmatic processes that occurred during the Neoarchean, using geochemical data and new insights garnered from isotopic surveys from the southern part of the Superior craton. We summarize current understanding of the evolution of the youngest (southern) part of the Superior craton that led to the stabilization (cratonization) of this continental lithosphere and how this evolution aligns with local and global geodynamic processes.

The Ordovician meteorite event in North America: Age of the Slate Islands impact structure, northern Lake Superior, Ontario, Canada

“…The ages are contemporaneous with the Kenoran orogeny in northern Minnesota and southwest Ontario (Adetunji et al., 2023; Gower & Clifford, 1981; Nunes & Thurston, 1980). Syenite of this timeframe is also associated with extensive gold deposits in Canadian greenstone belts (Chown et al., 2002; Corfu & Noble, 1992; Duke, 2021; Mathieu et al., 2023; Robert, 2001). The Slate Islands have been explored for gold since the early 20th century and are considered particularly favorable for mineralization (Sage, 1983, 1991).…”