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Geology Seminar Series - Dr. Camille Partin - Unlocking the tectonic and geochemical history of the Paleoproterozoic Belcher Group, Nunavut

Wed., Mar. 22, 2023 4:00 p.m. - Wed., Mar. 22, 2023 5:00 p.m.

Location: Zoom

You are invited to a URegina Geology Department Seminar Series talk:

Topic: Unlocking the tectonic and geochemical history of the Paleoproterozoic Belcher Group, Nunavut

Date and Time: Wednesday, March 22, 2023 at 4:00 PM

Zoom Link: https://uregina-ca.zoom.us/j/97728332215?pwd=L1hrNE5kejhpZlNJc2NnaXRpVkcxQT09

( Meeting ID: 977 2833 2215- - - - Passcode: 097240)

Presenter: Dr. Camille Partin, Dept. of Geological Sciences, University of Saskatchewan

Abstract:

The Paleoproterozoic Belcher Group was deposited from ca. 2015 to 1830 Ma during several notable transitions in Earth history. During this period in geological time major changes in atmospheric and oceanic O2 were occurring, as well as the amalgamation of the Nuna supercontinent. The Belcher Group largely escaped significant deformation during the Trans-Hudson orogen and experienced only prehnite-pumpellyite grade metamorphism, which is atypical for Paleoproterozoic sedimentary-volcanic basins. As a result, the Belcher Group preserves an excellent geological record of the Orosirian Period. Recent geochemical studies have shown that the Belcher Group and other contemporaneous successions record a crash in primary productivity in the oceans that accompanied a decline in atmospheric O2 that has been called the Deoxidation Event. This event occurred in the backdrop of major global orogenic events, which would be expected to promote increases in O2 based on trends seen in the Phanerozoic record.
The Belcher Group also plays an important role in understanding the dynamics of the Trans-Hudson orogen as it relates to the western Superior craton margin. Deposition of the Belcher Group initially began in a marginal marine environment with continental flood basalts, which then transitioned to tidal and near-shore settings. This transition reflects rifting and the development of a passive margin on the western Superior craton margin. The latter stages of deposition were influenced by convergent plate processes leading up to the Trans-Hudson orogen. A deeper water, offshore marine environment followed that included the extrusion of pillow basalt and volcaniclastic rocks during development of a syn-orogenic foredeep basin. The uppermost unit of the Belcher Group records molasse sedimentation in a fluvial to shallow marine environment. Recent interpretation of geophysical transects suggest that the Belcher Group was part of the development of critical wedge and an orocline in the Hudson Bay re-entrant.
New provenance analysis of the Belcher Group using coupled detrital zircon U-Pb and Hf isotope data has allowed us to delineate sedimentary sources that change greatly up-stratigraphy. Abundant literature data has allowed us to identify specific blocks within the Superior craton that were exposed and eroded during the deposition of the lower Belcher Group. A change in provenance from dominantly Archean to dominantly Paleoproterozoic sources occurred in concert with a change in paleoslope during the deposition of the upper Belcher Group. We identify provenance sources during the closing stages of the Manikewan Ocean from ca. 1850 to 1830 Ma that include intra-oceanic arc terranes and the Sugluk block.
The Belcher Group has 185 million years of stories to tell. This talk will discuss some recent research advances as well as community initiatives of the Belcher Islands Archipelago.