Paleoproterozoic Huronian basin: product of a Wilson cycle punctuated by glaciations and a meteorite impact

Abstract

The Huronian Supergroup (∼2.4–2.2 Ga) comprises up to 12 km of mainly sedimentary supracrustal rocks. The oldest Huronian unit, the Livingstone Creek Formation, is chemically and mineralogically immature. Significant chemical weathering and deposition of U-rich quartz pebble conglomerates followed deposition of the Livingstone Creek Formation and extrusion of the overlying, rift-related lavas of the Thessalon Formation. Much of the succeeding Huronian comprises climatically(?)-controlled tripartite cycles, each of which begins with glaciogenic diamictites, followed by mudstones and cross bedded arenaceous units. Huronian deposition is interpreted as the result of a partial Wilson cycle, involving rifting and development of a southward-facing passive margin. The ∼2.4 Ga Murray and Creighton granites have been considered by others to be co-eval with an early orogenic episode (Blezardian). Expected unconformities are, however, lacking and these granites, together with co-eval volcanic rocks and abundant soft sediment deformation structures are considered to be due to anorogenic processes during Huronian basin subsidence. The main deformation of the Huronian is probably related to the Penokean orogeny (∼1.89–1.8 Ga). Geochemical investigations have contributed to paleoclimatic and provenance studies and have helped to define basin-wide metasomatic events. A large impact at ∼1.85 Ga likely played an important role in formation of the Sudbury Igneous Complex (SIC) and deposition of fallback breccias of the Onaping Formation (basal Whitewater Group in the Sudbury basin). Overlying sedimentary rocks of the Whitewater Group are considered to be a fortuitously-preserved portion of a widespread flysch apron that spread across the southern margin of the Superior Province as a foreland basin fill, in response to the closure phase of the Wilson cycle during the Penokean orogeny. Geochronological data suggest that these events occurred during the Penokean orogeny.