Laminated sediments as high resolution paleoclimate archives in the Bering Sea (SO202-INOPEX)
Abstract
During the RV Sonne expedition SO202-INOPEX, sediment cores containing laminated sequences were collected from the Bowers Ridge, the Umnak Plateau and from the Bering Sea continental slope. The extensive occurrence of laminated sediments throughout the Bering Sea suggests that dysoxic conditions were comparatively widespread in this region. Previous work [e.g 1] shows that the laminations formed roughly during the Boelling-Alleroed and early Holocene. To constrain the precise timing of the laminite formation, a detailed age model was generated by means of AMS 14C dating of planktic and benthic foraminifers, mollusks and wood fragments. However, the establishment of an exact 14C-based age model is apparently complicated by water mass ventilation changes along Termination I. In order to better constrain past reservoir age changes, we used prominent tephra layer for core-core correlation and we correlated physical property and high resolution XRF data from our sediment cores with Greenland ice core records. Our radiocarbon dates of the laminated sequences are largely consistent with preliminary layer counting and suggest the occurrence of annually varved sequences during the Boelling-Alleroed and earliest Holocene. X-ray images and ultra-high resolution micro-XRF major element data reveal unprecedented details within the laminated sequences that reach up to 450 cm thickness at the northern Bering Sea slope. The study of these laminated sediments offers the unique opportunity to document interannual and decadal-scale climate variability during the transition from glacial to interglacial times with a time resolution rarely found in ocean sediments. This provides the baseline for better understanding of climate transfer mechanisms on the Northern Hemisphere. A further major goal of our study is to decipher the mechanisms responsible for the dysoxic conditons and why these are apparently restricted to millennial-scale warm intervals during the termination and the earliest Holocene. [1] Cook et al., 2005, Deep Sea Res. II 52, 2163-2173
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFMPP52A..07K
- Keywords:
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- 4901 PALEOCEANOGRAPHY / Abrupt/rapid climate change