Insights into the Geographic Sequence of Deglaciation in the Weddell Sea Embayment by Provenance of Ice-Rafted Debris


Contact
gerhard.kuhn [ at ] awi.de

Abstract

The geochemical and geochronological fingerprint of rock debris eroded and carried by ice streams may be used to identify the provenance of iceberg-rafted debris (IRD) in the marine sediment record. During ice retreat following glacial maxima, it has been shown that there is an increase in IRD accumulation in marine sediments underlying the western limb of the Weddell Gyre. Here we present IRD provenance records from sediment core PS1575-1 in the NW Weddell Sea, and interpret these records in terms of the geographic sequence of ice sheet retreat in the Weddell Sea embayment during the most recent deglaciation. We first characterize the source areas of eroded debris around the Weddell Sea Embayment, using published mapping of the embayment and new material from: 1. Till in modern moraines at the edges of ice streams, including the Foundation Ice Stream, the Academy Glacier, and the Recovery Glacier; and 2. Subglacial till and proximal glaciomarine sediment from existing cores located along the front of the Filchner and Ronne Ice Shelves, collected on past expeditions of the RV Polarstern. The analyses on these samples include 40Ar/39Ar hornblende and biotite thermochronology and U-Pb zircon geochronology on individual mineral grains, and K-Ar thermochronology, Nd isotopes, and clay mineralogy on the clay grain size fraction. Results so far indicate that samples along the front of the Filchner and Ronne Ice Shelves record the geochemical and geochronological fingerprint that would be expected from tracing ice flow lines back to the bedrock terranes. The Ronne (west), Hughes (central), and Filchner (east) sectors have distinguishable provenance source signatures, and further subdivision is possible. In core PS1575-1, downcore IRD provenance changes reflect iceberg output and ice sheet retreat from the different sectors of the embayment through the last deglaciation. The detrital provenance method of interpreting the geographic sequence of ice retreat can equally be applied to previous deglaciations of the Weddell Sea Embayment.



Item Type
Conference (Poster)
Authors
Divisions
Primary Division
Programs
Primary Topic
Peer revision
Not peer-reviewed
Publication Status
Published
Event Details
American Geophysical Union, Fall Meeting 2017, 11 Dec 2017 - 15 Dec 2017, New Orleans.
Eprint ID
46224
Cite as
Williams, T. , Hemming, S. R. , Licht, K. , Agrios, L. , Brachfeld, S. , van de Flierdt, T. , Hillenbrand, C. D. , Ehrmann, W. , Zhai, X. , Cai, Y. , Corley, A. D. and Kuhn, G. (2017): Insights into the Geographic Sequence of Deglaciation in the Weddell Sea Embayment by Provenance of Ice-Rafted Debris , American Geophysical Union, Fall Meeting 2017, New Orleans, 11 December 2017 - 15 December 2017 .


Share

Research Platforms

Campaigns


Actions
Edit Item Edit Item