Determination of Antarctic Ice Sheet stability over the last ∼500 ka through a study of iceberg-rafted debris

• Published in: Paleoceanography
• Main Authors: Teitler, Lora, Warnke, Detlef A., Venz, Kathryn A., Hodell, David A., Becquey, Sabine, Gersonde, Rainer, Teitler, Winston
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2010
• Subjects: 01 - Climate Change and Earth-Ocean Atmosphere Systems; Antarctic; East Antarctic Ice Sheet; West Antarctic Ice Sheet; Antarc*; Ice Sheet; Iceberg*; South Atlantic Ocean
• Online Access: http://eprints.esc.cam.ac.uk/2080/; http://eprints.esc.cam.ac.uk/2080/1/Hod__AGU_2008PA001691.pdf; http://europa.agu.org/?uri=/journals/pa/pa1001/2008PA001691/2008PA001691.xml&view=article; https://doi.org/10.1029/2008PA001691

We have analyzed ice‐rafted debris (IRD) from the South Atlantic Ocean (∼43°S, 9°E) in order to investigate Antarctic Ice Sheet history during the late Pleistocene; the cores examined for this study include piston core TN057‐6‐PC4 and Ocean Drilling Program Leg 177 drill core Site 1090 (177‐1090). Over the last 500 ka at this distal location, IRD arrived during both glacials and interglacials. IRD is present even during warmer intervals, is greatest during colder intervals, and is absent only during terminations and a few other brief intervals. Four different methods are used to normalize the IRD counts, which are then compared to support our interpretation. Several other high‐quality climate proxies from this location also aid our interpretations. We conclude that sea surface temperatures are the primary control on the delivery of IRD to this site. During cold times more icebergs survived to reach this distal location. During warm times only a few of the largest icebergs could travel this far. Garnets found in these sediments suggest a likely East Antarctic origin for the IRD; the presence of garnets even during warm intervals further strongly supports that the iceberg source must be the East Antarctic Ice Sheet (EAIS). Therefore, the EAIS must have continued to reach the ocean at least in some part of its margin throughout the last 500 ka. On the other hand, we cannot specifically trace any IRD to the West Antarctic Ice Sheet (WAIS), so WAIS persistence cannot be tested. A particular radiolarian, identified as Dictyocoryne profunda (Ehrenberg) (sensu Boltovskoy (1998)), shows up in the examined size fraction generally only during warm phases. We suggest that D. profunda is a sensitive indicator of warm water temperatures and that it deserves further study.