Marine Sediment Cores from the northern Prince Gustav Channel: A Record of the Holocene Climatic Optimum Confirms Trans-Peninsula Warmth ~6000 yr BP

Lichtenstein, S.J.¹, Drake, A.J.¹, Domack, E.¹, Camerlenghi, A.², Gilbert, R.³, Brachfeld, S.⁴, Leventer, A.⁵

¹ Department of Geology, Hamilton College, Clinton, New York, USA
² Istituto Nazionale di Oceanografia e di Geofisica Sperimentale, Sgonioco (TS) Italy
³Department of Geography, Queens University, Kingston, Ontario, CANADA
⁴Byrd Polar Research Center, Ohio State University, 108 Scott Hall, 1090 Carmack Road, Columbus, OH 43210
⁵Department of Geology, Colgate University, 13 Oak Drive, Hamilton, NY 13346

Contact e-mail: edomack@hamilton.edu

Two marine geological investigations were conducted within the northern Prince Gustav Channel on the eastern side of the Antarctic Peninsula (NBP '00-03 & NBP '01-07). Within the channel lies the Vega Drift, a sediment system that accumulates sediment derived from circulation within the Erebus and Terror Gulf, NW Weddell Sea. We present paleoenvironmental proxies of grain size, total organic carbon, magnetic susceptibility, ice rafted debris and sedimentary structures from Kasten Cores (KC) 36, 37, and 38, and Jumbo Piston Core (JPC) 38, taken from three locations within the drift. The upper portions of all four cores consist of bioturbated diatomaceous mud/ooze with intervals of laminated diatom ooze. Sedimentary structures contained within the four cores showed similarities including seasonal laminations of diatomaceous ooze, bioturbation indicated by mottled structures, and co-variant fluctuations in ice rafted debris. JPC 38 extends to 20 mbsf and displays similar sedimentary characteristics as the kasten cores until a depth of 7.8 meters. Below this depth very thin laminations of ooze and mud dominate and resemble classic varves. At 15.2 meters, the laminations disappear, the sediment becomes very clay rich, and ice rafted debris increases. This change in sediment character is unlike anything observed on the western side of the Antarctic Peninsula and likely represents the response of local glaciers with elevated ELA's to a middle Holocene warming event. This climatic optimum is interpreted to have induced extensive melt-water plume formation and increased iceberg calving leading to the observed changes in sediment facies. Such a change in sediment regime has not yet expressed itself within modern sediments of the drift despite over 40 years of regional warming. However the melt facies are similar to sediment now being deposited within fjords along the southern coast of James Ross Island. Four in-situ molluscs from site 38 have been radiocarbon dated. The ages range from an uncorrected ¹⁴C age of 1890 yr. BP (calibrated 640 yr.BP) at 244 cm, to an uncorrected ¹⁴C age of 7290 yr. BP (calibrated 6950 yr.BP) at 1661 cm. Using the curve for the calibrated ages of these samples, we can infer the timing of the major facies changes observed within JPC 38. The change from inter-laminated diatomaceous ooze and mud to continuous laminations occurred approximately 2940 yr.BP. The shift from varves to the homogeneous clay-rich section occurred approximately 6415 yr.BP. Ikiate crystals (calcium carbonate hexahydrate), which are an unusual occurrence on the Antarctic Peninsula, were also found at multiple depths in KC 37 and JPC 3.

*Calibrated using Delta-R of 826 +/- 50

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This work was supported by the National Science Foundation Office of Polar Programs Research Experience for Undergraduates. We thank Captain Joseph Borkowski III, the crew of the Nathaniel B. Palmer, and the staff of Raytheon Polar services for giving us the opportunity to conduct this research.