Sedimentary record of the western Amundsen Sea Embayment

DOI

The Amundsen Sea Embayment (ASE) drains approximately 35% of the West Antarctic Ice Sheet (WAIS) and is one of the most rapidly changing parts of the cryosphere. In order to predict future ice-sheet behaviour, modellers require long-term records of ice-sheet melting to constrain and build confidence in their simulations. Here, we present detailed marine geological and radiocarbon data along three palaeo-ice stream tributary troughs in the western ASE to establish vital information on the timing of deglaciation of the WAIS since the Last Glacial Maximum (LGM). We have undertaken multi-proxy analyses of the cores (core description, shear strength, x-radiographs, magnetic susceptibility, wet bulk density, total organic carbon/nitrogen, carbonate content and clay mineral analyses) in order to: (1) characterise the sedimentological facies and depositional environments; and (2) identify the horizon(s) in each core that would yield the most reliable age for deglaciation. In accordance with previous studies we identify three key facies, which offer the most reliable stratigraphies for dating deglaciation by recording the transition from a grounded ice sheet to open marine environments. These facies are: i) subglacial, ii) proximal grounding-line, and iii) seasonal open-marine. In addition, we incorporate ages from other facies (e.g., glaciomarine diamictons deposited at some distance from the grounding line, such as glaciogenic debris flows and iceberg rafted diamictons and turbates) into our deglacial model. In total, we have dated 78 samples (mainly the acid insoluble organic (AIO) fraction, but also calcareous foraminifers), which include 63 downcore and 15 surface samples. Through careful sample selection prior to dating, we have established a robust deglacial chronology for this sector of the WAIS. Our data show that deglaciation of the western ASE was probably underway as early as 22,351 calibrated years before present (cal 44 yr BP), reaching the mid-shelf by 13,837 cal yr BP and the inner shelf to within c.10-12 km of the present ice shelf front between 12,618 and 10,072 cal yr BP. The deglacial steps in the western ASE broadly coincide with the rapid rises in sea-level associated with global meltwater pulses 1a and 1b, although given the potential dating uncertainty, additional, more precise ages are required before these findings can be fully substantiated. Finally, we show that the rate of ice-sheet retreat increased across the deep (up to1,600 m) basins of the inner shelf, highlighting the importance of reverse slope and pinning points in accelerated phases of deglaciation.

Further relevant data sets: Hillenbrand et al. (2010), doi:10.1594/PANGAEA.715974, Ehrmann et al. (2010), doi:10.1594/PANGAEA.755199

Supplement to: Smith, James A; Hillenbrand, Claus-Dieter; Kuhn, Gerhard; Larter, Robert D; Graham, Alastair G C; Ehrmann, Werner; Moreton, Steven Grahame; Forwick, Matthias (2011): Deglacial history of the West Antarctic Ice Sheet in the western Amundsen Sea Embayment. Quaternary Science Reviews, 30(5-6), 488-505

Identifier
DOI https://doi.org/10.1594/PANGAEA.754968
Related Identifier https://doi.org/10.1016/j.quascirev.2010.11.020
Metadata Access https://ws.pangaea.de/oai/provider?verb=GetRecord&metadataPrefix=datacite4&identifier=oai:pangaea.de:doi:10.1594/PANGAEA.754968
Provenance
Creator Smith, James A ORCID logo; Hillenbrand, Claus-Dieter ORCID logo; Kuhn, Gerhard ORCID logo; Larter, Robert D ORCID logo; Graham, Alastair G C ORCID logo; Ehrmann, Werner; Moreton, Steven Grahame ORCID logo; Forwick, Matthias ORCID logo
Publisher PANGAEA
Publication Year 2011
Funding Reference German Research Foundation https://doi.org/10.13039/501100001659 Crossref Funder ID 5472008 https://gepris.dfg.de/gepris/projekt/5472008 Priority Programme 1158 Antarctic Research with Comparable Investigations in Arctic Sea Ice Areas
Rights Creative Commons Attribution 3.0 Unported; https://creativecommons.org/licenses/by/3.0/
OpenAccess true
Representation
Language English
Resource Type Supplementary Publication Series of Datasets; Collection
Format application/zip
Size 76 datasets
Discipline Earth System Research
Spatial Coverage (-118.164W, -74.136S, -111.624E, -71.814N); Amundsen Sea
Temporal Coverage Begin 2006-01-24T05:46:00Z
Temporal Coverage End 2006-03-10T20:11:00Z