GSA Annual Meeting in Phoenix, Arizona, USA - 2019

Paper No. 11-2
Presentation Time: 8:30 AM


MAMMONE, Nicholas M1, BEKKER, Andrey1 and CHAMBERLAIN, Kevin2, (1)Dept. of Earth and Planetary Sciences, Univ. of California, Riverside, 900 University Avenue, Riverside, CA 92521, (2)Dept. of Geology and Geophysics, Univ. of Wyoming, Laramie, WY 82071

Paleogeography is a critical component to providing a backdrop for environmental changes, yet it remains controversial for the early Paleoproterozoic. The Snowy Pass Supergroup (SPS), a Paleoproterozoic supracrustal succession on the SE Wyoming craton (WC), has been historically correlated with the Huronian Supergroup (HS) of the Superior craton (SC) based on similar lithostratigraphic patterns, suggesting deposition in the same basin. This study presents LA-ICP-MS U-Pb detrital zircon age data for the SPS, further constraining the paleogeography of these cratons. Lithostratigraphically correlative units of the SPS and HS show similar, primarily Archean, age modes at ~2.55, 2.7, and 2.85 Ga throughout both supergroups (HS data are from Craddock et al., 2013). Notably, the ~2.55 Ga mode, which is mostly absent in the lower SPS and HS, emerges as a significant mode in the upper SPS starting with the Lookout Schist (and the correlative Bar River Fm, HS). Correlation between the HS and SPS breaks in the upper SPS at the Nash Fork Fm, which bears unique modes at ~2.1 and ~2.2 Ga, whereas deposition of the HS was terminated before ~2.22 Ga when the Nippissing dikes intruded. The Paleoproterozoic link between the WC and SC is clear, but the debate as to whether the Hearne or Kola-Karelia craton was east of the WC is still ongoing. Detrital zircon data for the Paleoproterozoic Red Creek Quartzite (RCQ) on the SW WC exhibits an even more pronounced ~2.55 Ga mode, potentially linking this laterally extensive mode to the ~2.50–2.55 Ga MacQuoid Orogen on the NW Hearne craton. Additionally, the appearance of a globally unique ~2.3 Ga mode in the Lookout Schist of the upper SPS (also seen in tuff layers of the upper HS) and its steady decrease upsection hints at likely sourcing from the ~2.3 Ga Arrowsmith Orogen on the W Rae craton. The paleogeographic position of the Rae and Hearne cratons is disputed, but similarities in tectonostratigraphy of supracrustal successions on both of these cratons (Rainbird et al., 2010) and zircon Hf isotope records (Regan et al., 2017) suggest a Paleoproterozoic linkage. The ~2.55 and ~2.3 Ga age modes present in the SPS and RCQ suggest that these cratons were east of the WC between ~2.45 and 2.32 Ga and that the Arrowsmith Orogeny changed the provenance to, and eventually ended deposition in, the intracratonic SPS and HS basins.