COLLABORATIVE RESEARCH: Calibrating the Cryogenian in the Yukon

COLLABORATIVE RESEARCH: Calibrating the Cryogenian in the Yukon

Francis MacDonald.1148499, Harvard University;

Mark Schmitz.1148058, Boise State University

ABSTRACT

The Snowball Earth hypothesis has galvanized broad interest in Neoproterozoic geology; however, the hypothesis remains controversial largely due to uncertainty about the timing, duration, and initiation mechanism of global glaciation. With previous and preliminary studies, we have demonstrated that the age of Sturtian glacial deposits in the Yukon is indistinguishable from the age of the Franklin large igneous province (LIP), which was emplaced on the eastern margin of Laurentia, in the tropics, in an ideal position for being chemically weathered. This is intriguing, because basalt is more weatherable than average continental crust, and it has been proposed that Snowball Earth events were initiated by an increase in weatherbility and a concomitant increase in CO2 consumption. However, the age range and error bars on the Franklin LIP are still too large to determine if the volcanism was long- or short-lived, and if the glaciation occurred during, before or after the main pulse of volcanism. With the proposed research PIs intend to constrain the timing and duration of the Sturtian glaciation and the Franklin LIP in the Yukon with high resolution U-Pb ID-TIMS dating of magmatic zircons and LA-ICPMS dating of detrital zircons that bracket the glacial deposits.