IODP Exp 323 Site U1342 from the Bering Sea may indicate past changes in ocean ventilation and climate
Abstract
The Bering Sea represents a gateway between the North Pacific Ocean and the Arctic Ocean and may provide insights into past changes in circulation between the oceans. Changes in ocean circulation within the Bering Sea may be related to global climate cycles on orbital to sub-orbital timescales, but the role and nature of Bering Sea climate changes has never been studied in detail before long, continuous cores were drilled as part of the Integrated Ocean Drilling Program (IODP) Expedition 323. IODP Site U1342 is ideally situated to reconstruct changes in climate and ocean circulation. As the shallowest of the Exp 323 sites, it is located within the present-day oxygen minimum zone (OMZ), which may display changes in intensity and depth in response to variations in intermediate water ventilation and surface productivity. Alternations within the core between massive bioturbated sediments, dominated by fine-grained siliciclastic and diatom oozes that are sometimes laminated, attests to large changes in climate and OMZ conditions recorded at this site. We present new δ13C and δ18O records at IODP Site U1342 from benthic foraminifera species Uvigerina perigrina. Our results show variations in δ18O indicating the presence of all late Pleistocene marine isotope stages. Comparison of our δ18O record with the lithologic changes indicates that the low-density, diatom-rich (sometimes laminated) intervals at this site occur at higher frequencies than the 100K glacial cycles. These intervals are found predominantly in sediments deposited during interglacial times, although not during the warmest part of the interglacials. Additionally, our results show that δ13C values are generally lower in glacial intervals. Overall, future work at IODP Site U1342 will determine the history of past changes in ocean ventilation within the Bering Sea.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFMPP31B1863K
- Keywords:
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- 1050 GEOCHEMISTRY / Marine geochemistry;
- 1051 GEOCHEMISTRY / Sedimentary geochemistry;
- 1635 GLOBAL CHANGE / Oceans;
- 4900 PALEOCEANOGRAPHY