CONTINENTAL-SCALE GLACIATION DURING THE PALEOPROTEROZOIC: DETRITAL ZIRCON EVIDENCE FROM THE SNOWY PASS SUPERGROUP, WYOMING

The sedimentologic, stratigraphic, and geochronologic similarities between the Paleoproterozoic Huronian Supergroup of the southern Superior Province and the Snowy Pass Supergroup of the southern Wyoming Province are well established. Both successions are interpreted to have been deposited in the same epicontinental or continental margin basin on the Superia Supercontinent; each succession also contain glaciogenic diamictites. In the Snowy Pass Supergroup (~2.4-2.1 Ga) glaciogenic strata are evident in the Vagner and Headquarters formations. Here we present detrital zircon data (z=838) for the Vagner (s=4) and Headquarters (s=2) to determine if these units were locally sourced from the Wyoming Province and thus limited in scale, or if a Superior Province source and continental-scale glaciation is evident. Detrital zircon U-Pb data was obtained from the University of Arizona Laserchron Center. The Superior and Wyoming source areas were characterized using published detrital zircon age data (n>1200 zircons) for each region. Our new data was analyzed using the Detrital Zircon Unmix routine in Isoplot. Each of our six diamictite samples have a prominent unimodal age peak of ~2.7 Ga, and the Unmix routine indicates a greater than 95% contribution from a Superior craton source area. Our data indicates that the Superior and Wyoming provinces were connected during the Vagner and Headquarters glaciations. Moreover, glacial transport of more than 1000 km from the Superior Province is evident. Thus, this is the first direct establishment of continental-scale glaciation during the Paleoproterozoic, which is on par with the extent of the Neoproterozoic, Late Paleozoic, and Quaternary glaciations.