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| Titel |
Sedimentary organic matter and carbonate variations in the Chukchi Borderland in association with ice sheet and ocean-atmosphere dynamics over the last 155 kyr |
| VerfasserIn |
S. F. Rella, M. Uchida |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 8, no. 12 ; Nr. 8, no. 12 (2011-12-06), S.3545-3553 |
| Datensatznummer |
250006239
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| Publikation (Nr.) |
 copernicus.org/bg-8-3545-2011.pdf |
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| Zusammenfassung |
| Knowledge on past variability of sedimentary organic carbon in the Arctic
Ocean is important to assess natural carbon cycling and transport processes
related to global climate changes. However, the late Pleistocene
oceanographic history of the Arctic is still poorly understood. In the
present study we show sedimentary records of total organic carbon (TOC),
CaCO3, benthic foraminiferal δ18O and the coarse grain
size fraction from a piston core recovered from the northern Northwind Ridge
in the far western Arctic Ocean, a region potentially sensitively responding
to past variability in surface current regimes and sedimentary processes
such as coastal erosion. An age model based on oxygen stratigraphy,
radiocarbon dating and lithological constraints suggests that the piston
core records paleoenvironmental changes of the last 155 kyr. TOC shows
orbital-scale increases and decreases that can be respectively correlated to
the waxing and waning of large ice sheets dominating the Eurasian Arctic,
suggesting advection of fine suspended matter derived from glacial erosion
to the Northwind Ridge by eastward flowing intermediate water and/or surface
water and sea ice during cold episodes of the last two glacial-interglacial
cycles. At millennial scales, increases in TOC might correlate to a suite of
Dansgaard-Oeschger Stadials between 120 and 45 ka before present (BP)
indicating a possible response to abrupt northern hemispheric temperature
changes. Between 70 and 45 ka BP, closures and openings of the Bering Strait
could have additionally influenced TOC variability. CaCO3 content tends
to anti-correlate with TOC on both orbital and millennial time scales, which
we interpret in terms of enhanced sediment advection from the carbonate-rich Canadian
Arctic via an extended Beaufort Gyre during warm periods of the last two
glacial-interglacial cycles and increased organic carbon advection from the
Siberian Arctic during cold periods when the Beaufort Gyre contracted. We
propose that this pattern may be related to orbital- and millennial-scale
variations of dominant atmospheric surface pressure systems expressed in
mode shifts of the Arctic Oscillation. |
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