Holocene climate change in the Bransfield Basin, Antarctic Peninsula: evidence from sediment and diatom analysis

Abstract We present the first study from the Bransfield Basin that extends through the Holocene, recording the variable climate history back to the decoupling of the ice sheet from the continental shelf ~10 650 calendar years before present (cal yr bp ). Detailed sediment analysis reveals three stra...

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Bibliographic Details
Published in:Antarctic Science
Main Authors: Heroy, David C., Sjunneskog, Charlotte, Anderson, John B.
Format: Article in Journal/Newspaper
Language:English
Published: Cambridge University Press (CUP) 2007
Subjects:
Geology
Ecology, Evolution, Behavior and Systematics
Oceanography
Antarc*
Antarctic
Antarctic Peninsula
Antarctic Science
Antarctica
Deception Island
Ice Sheet
Ice Shelf
Online Access:http://dx.doi.org/10.1017/s0954102007000788
https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0954102007000788
Description
Summary:Abstract We present the first study from the Bransfield Basin that extends through the Holocene, recording the variable climate history back to the decoupling of the ice sheet from the continental shelf ~10 650 calendar years before present (cal yr bp ). Detailed sediment analysis reveals three stratigraphic units in PC-61 concomitant with three sedimentary environments, similar to sedimentary facies reported elsewhere: 1) subglacial, 2) glacial proximal/sub-ice shelf, and 3) open marine. These interpretations are based on a variety of sedimentological criteria, supported by ten AMS radiocarbon dates and detailed diatom analysis. We note two significant volcanic ash layers (tephra) at 3870 and 5500 cal yr bp from nearby Deception Island. Based on diatom assemblage analysis, we identify five separate climate regimes, highlighting a significantly shorter Mid-Holocene Climatic Optimum than reported by other studies (6800–5900 cal yr bp ). This period is marked by the highest Eucampia antarctica var. antarctica and Fragilariopsis curta abundance, total diatom abundance, sediment accumulation rates, and low magnetic susceptibility. We also identify a less pronounced Neoglacial period relative to other studies, which includes an increase of Cocconeis/Rhizosolenia spp. assemblage related to unstable surface water conditions. Such observations probably reflect important regional variations in atmospheric or ocean circulation patterns.

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