9-1 Source to Sink Sedimentation across the Great Unconformity in the Northern Great Basin, USA

Session: Sedimentary Systems and Provenance in the Western Cordillera (Posters)

Presenting Author:

Authors:

Abstract:

The Great Unconformity is an iconic gap in the rock record of North America separating Archean and Proterozoic crystalline and metamorphic basement from overlying Paleozoic sedimentary rocks. In a source-to-sink framework, sediment removed from the continental interior must have been delivered to marginal basins, providing an opportunity to test different models of genesis against the sedimentary record. In one model, the Great Unconformity was generated via Cryogenian Snowball Earth glacial erosion. This model predicts Cryogenian erosion focused on the Stenian and Middle Cryogenian sedimentary successions on the margins due to heightened ice flow and large escarpments caused by sea level fall. Alternatively, it has been proposed that erosion was driven by mantle upwelling under Laurentia following the rifting of the supercontinent Rodinia and focused on the erodibility contrast between basement and sedimentary rock cover. In this model, erosion would be concentrated on the sedimentary cover of the continental interior and would have continued through the Ediacaran and into the Cambrian with a gradual influx of older basement sources towards the top of the succession. Here, we present new U-Pb LA-ICPMS detrital zircon data, petrographic analysis, and sequence stratigraphic interpretations from measured stratigraphic sections spanning an east to west transect across northern Utah to track the delivery of sediment to the basin and test between these mechanisms. We document stratigraphic evidence for deposition in outer shelf to slope settings through the Ediacaran, including channelized deposits in turbidites and an overall prograding margin. A shift in provenance from dominantly Mesoproterozoic to Paleoproterozoic sources is interpreted as erosion down through Stenian and Tonian cover to older, less easily erodible basement. Local incision to basement occurred during Cryogenian rifting and Ediacaran channelization of the platform margin, but the major shift in detrital zircon provenance occurred in latest Ediacaran to Cambrian strata. Our results are consistent with a progressive Neoproterozoic removal of a sedimentary carapace covering the craton.

Geological Society of America Abstracts with Programs. Vol. 58, No. 3, 2026

© Copyright 2026 The Geological Society of America (GSA), all rights reserved.