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The AAPG/Datapages Combined Publications Database
Houston Geological Society Bulletin
Abstract
Abstract: Onset of a Small But Significant Regional Climate Change
Documented in High-resolution Late Holocene Sediment Cores from
the Maritime Western Antarctic Peninsula
The glaciomarine environment of the Antarctic Peninsula
region is one of the fastest warming places on earth.
However, late Holocene paleoclimate reconstructions in this
region are separated by large distances and details of past changes
remain uncertain. This study focuses on a marine sediment core
collected in 2007 from the deep Central Bransfield Basin in 1,980 m
of water and provides a central tie for other published studies in
this region. The core lithology is dominantly diatomaceous mud
with some turbidites. Radiocarbon and cesium dates have been
used to create an age model that spans the interval 3600 cal yr BP
to present. This chronostratigraphic framework was used to
establish five units which are grouped into two super-units, based
upon: detailed facies descriptions, laser particle size analysis,
x-ray radiographic analysis, multi-sensor core logger data,
elemental and isotopic data. The two super-units that have been
recognized are a lower super-unit (3559-1600 cal yr BP) and an
upper super-unit (1600 cal yr BP present). The upper super-unit
signature is described by elevated δ13C coupled with decreasing
δ15N values, lower magnetic susceptibility values and less
frequent facies changes. This signature is interpreted as an
increase in primary productivity, and a potential mechanism for
this small but significant change may be an increase in surface
water temperature and/or shortening of the sea-ice season. The
five units that are recognized are comparable with known climatic
transitions across the western Antarctic Peninsula: the
Mid-Holocene Climatic Optimum
, the Neoglacial, the Medieval
Warm Period, the Little Ice Age, and rapid recent warming. The
super-unit boundary coincides with an early onset of the
Medieval Warm Period (1600 cal yr BP) which is typically at 1200
cal yr BP. These changes in the Bransfield Basin have been
compared to other published records from the Bransfield Basin,
Firth of Tay, Maxwell Bay, and Palmer Deep. These comparisons
highlight the diachronous nature of climate change across the
Mid-Holocene Climatic
Optimum
to Neoglacial boundary. There
is evidence across the region for the onset of change at about
1600 cal yr BP, although the exact timing remains uncertain.