A multiproxy study of past environmental changes in the Sea of Okhotsk during the last 1.5 Ma

Long chain diols have been detected in a wide range of environments and have been used to reconstruct past environmental changes, however only a few long-term records exist to date. Here we reconstructed past environmental changes in the central Sea of Okhotsk over the last 1.5 million years, coveri...

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Bibliographic Details
Published in:Organic Geochemistry
Main Authors: Lattaud, Julie, Lo, Li, Zeeden, Christian, Liu, Ya-Jun, Song, Sheng-Rong, van der Meer, Marcel T. J., Damste, Jaap S. Sinninghe, Schouten, Stefan
Format: Report
Language:English
Published: PERGAMON-ELSEVIER SCIENCE LTD 2019
Subjects:
Geochemistry & Geophysics
Sea of Okhotsk
Mid-Pleistocene Transition
LDI
TEX86
U-37(K)'
Biogenic opal
Long-chain diols
ICE-RAFTED DEBRIS
MIDDLE PLEISTOCENE TRANSITION
HYDROGEN ISOTOPIC COMPOSITION
MILLENNIAL-SCALE VARIATIONS
TERRESTRIAL ORGANIC-MATTER
BRANCHED TETRAETHER LIPIDS
GLOBAL CLIMATE CHANGES
CHAIN DIOL PROXIES
LONG-TERM CHANGES
SURFACE TEMPERATURE
Okhotsk
Sea ice
Online Access:http://ir.gig.ac.cn/handle/344008/51076
https://doi.org/10.1016/j.orggeochem.2019.04.003
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Summary:Long chain diols have been detected in a wide range of environments and have been used to reconstruct past environmental changes, however only a few long-term records exist to date. Here we reconstructed past environmental changes in the central Sea of Okhotsk over the last 1.5 million years, covering the Mid-Pleistocene Transition (MPT). Sea surface temperatures (SST) reconstructed using the Long-Chain Diol Index (LDI) reflects glacial/interglacial changes. However, when compared with other organic paleothermometers (U-37(K)'( )and TEX86L) the LDI-SST is lower during interglacials and similar or higher during glacials, possibly suggesting a shift of diol production season during interglacials. The LDI-SST does not change in periodicity around the MPT as observed for the TEX86L, likely due to this seasonal shift. Diatom productivity, as recorded by 1,14-diols and biogenic opal content, increased during the main deglaciations with a succession from Proboscia diatoms to diatoms with a more heavily silicified shell, confirming that primary productivity in the central Sea of Okhotsk is driven by sea-ice progress and retreat. In contrast to the LDI-SST, the 1,14-diols record shows a change in periodicity around the MPT from 41- to 100-kyr cycle, suggesting an influence of orbital parameters on diatom productivity. In the central Sea of Okhotsk, the relative amount of C-32 1,15-diol (F-C32 (1,15)), a proxy for riverine input, correlates with sea-level change with more riverine-derived material reaching the core site when the Amur River mouth is closer at lower sea-levels. In agreement, F-C32 (1,15) shows a change in periodicity during the MPT, with the appearance of a 100-kyr cycle. Our results show that the long chain diols can provide important paleoceanographic information in subpolar environments over long time scales, but that temperature reconstructions can be severely impacted by changes in seasonality. (C) 2019 The Authors. Published by Elsevier Ltd.

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