Late Quaternary paleoenvironment of the Ross Sea continental shelf, Antarctica

Abstract

ABSTR ACT. Based on sedimentological a nd micropaleontological work on three sediment cores coll ected at about 167° E in the western Ross Sea, Antarctica, and accelerator mass spectrometer 14C ages of organic carbon, we have reconstructed environmental changes in the area during the late Quaternary. Since 38 ka BP a t latest, this area was a m a rine environment with low productivity. A grounded ice sheet advanced and loaded the sediments before about 30-25 ka BP. After 25 ka BP, th e so uth ernmost site (76°46' S) was covered by floating ice (shelf ice ), preventing deposition of coarse terrigenous materials and maintaining a supply of di atom tests a nd organic carbon until 20 ka BP. The northernmost site (74°33' S ) was in a marin e environment with a mod erate productivity influenced by shelf ice/ice sheet after about 20 ka BP. Since about 10 ka BP' a sedimentary environment similar to the present-day one has prevailed over this area.

Record of the early Holocene warming in a laminated sediment core from Cape Hallett Bay (Northern Victoria Land, Antarctica)

“…For example, highly laminated sediments characterize the drift area of the Pacific margin of the Antarctic Peninsula (Pudsey and Camerlenghi, 1998;Lucchi et al, 2002), Palmer Deep and Gerlache Strait (Leventer et al, 2002;Goodridge, 1999Goodridge, -2000, the MacRobertson Shelf (Harris, 2000), the George V continental shelf (Wilkes Land Margin: Domack and Anderson, 1983;Domack, 1988;Brancolini and Harris, 2000;Presti et al, 2003), and outer slope areas of the Ross Sea embayment (Bonaccorsi et al, 2000). In the inner shelf of the Ross Sea, laminated sediments are reported by Nishimura et al (1998) (north of Ross Island), Leventer et al (1993) Harbour) and Colizza et al (2003) (Wood Bay area). In general, the preservation of parallel lamination in marine sediment is considered a proxy for anoxic conditions, that exclude the presence of a benthic community, or a very high sedimentation rate in areas characterized by upwelling or by favorable oceanographic conditions (Grigorov et al, 2002;Cofaigh and Dowdswell, 2001).…”

Pre-LGM open-water conditions south of the Drygalski Ice Tongue, Ross Sea, Antarctica

“…The age of the base unit fitted well with other radiocarbon ages obtained from superficial muddy units of other cores of the western Ross Sea. Just south of the Drygalski Ice Tongue, the onset of open marine conditions is dated back to 9.5-9.9 kyr BP (following Nishimura et al 1998.…”

“…Just south of the Drygalski Ice Tongue, the onset of open marine conditions is dated back to 9.5–9.9 kyr bp (following Nishimura et al . 1998, Domack et al . 1999, Cunningham et al .…”

Drastic changes in Depositional Environments at the Ross Sea Continental Margin since the Mid-Pleistocene: More evidence for West Antarctic Ice Sheet collapse

“…Thus, studying the sedimentation pattern in this region is critical in elucidating paleoceanographic changes and historical ice sheet dynamics. Recent geological investigations underscore the significance of comprehending past interactions between the ocean and ice sheets in the Ross Sea sector (Nishimura et al, 1998;Jacobs et al, 2002;Chow and Bart, 2003;Bart and Owolana, 2012;McKay et al, 2012b;Halberstadt et al, 2016;Anderson et al, 2019;McKay et al, 2019;Silvano et al, 2020), particularly in light of the retreating West Antarctic Ice Sheet (WAIS) (Pattyn and Morlighem, 2020). The ANDRILL 1-B core revealed 28 glacial-interglacial cycles between 5 to 1 Ma, with several hiatuses in sediment record; probably representing periods of glacial erosion (Naish et al, 2009).…”