T11 Precambrian Linkages across Laurentia: Looking for Geological, Geophysical, and Paleogeographic Connections and Controversies Associated with the Growth and Tectonic Evolution of Laurentia from the Neoarchean to the Neoproterozoic I

Sunday, 22 September 2019
8:00 AM - 12:00 PM
Room 229B, North Building

INSIGHTS INTO THE EARLY PALEOPROTEROZOIC PALEOGEOGRAPHY FROM DETRITAL ZIRCON GEOCHRONOLOGY OF SUPRACRUSTAL SUCCESSIONS ON THE SOUTHERN MARGIN OF THE WYOMING CRATON

Paper number: T11-3
Program: Technical Sessions
Time: 8:30 AM – 8:45 AM

Authors

Abstract

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.

Geological Society of America Abstracts with Programs. Vol. 51, No. 5

doi: 10.1130/abs/2019AM-337629

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