Unraveling the Chukchi Shelf sediments: insights into past ice sheet extent and gas migration

Abstract

Marine geophysical methods are utilized to image sedimentary deposits on shelf areas and continental slopes, offering insights into permafrost existence, gas migration, and the historical dynamics of ice sheets. This study focuses on the depositional history of outer Chukchi Shelf sediments and adjacent Chukchi Borderland, investigating glacial periods' impact on the sea floor, specifically a potential ice sheet along the Beringia continental margin. Reprocessed seismic data from 2011, part of a tectonic study on the Chukchi Shelf, reveals a glacial unconformity and distinctive seafloor structures indicative of multiple ice masses. Along the Beringian margin, varying thicknesses of glacial deposits, reaching 450m in certain areas, hint at the extent of an ice sheet and ice stream dynamics. Additionally, seismic data highlights migration structures of rising methane, suggesting its release into the water column, though typical gas seepage surface features are absent. The absence of large-scale marine permafrost on the Chukchi Shelf is indicated by seismic velocities. Overall, these findings provide crucial information for further geological exploration of this previously understudied continental margin, shedding light on its glacial history and potential methane outgassing.