Journal of Tropical Oceanography ›› 2020, Vol. 39 ›› Issue (6): 77-92.doi: 10.11978/2019090CSTR: 32234.14.2019090

• Marine Geology • Previous Articles     Next Articles

The source of glycerol dibiphytanyl glycerol tetraethers and temperature reconstruction since 8.2 ka in the central Okinawa Trough

LIU Lei1,3(), XU Lanfang1, GUAN Hongxiang1(), SUN Zhilei2, WANG Libo2, MAO Shengyi1, LIU Lihua1, WU Nengyou2   

  1. 1. Key Lab of Renewable Energy and Gas Hydrate, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, China
    2. Qingdao Institute of Marine Geology, China Geological Survey, Qingdao 266071, China
    3. University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2019-09-18 Revised:2020-03-10 Online:2020-10-10 Published:2020-04-16
  • Contact: GUAN Hongxiang E-mail:sc170130@mail.ustc.edu.cn;guanhx@ms.giec.ac.cn
  • Supported by:
    National Natural Science Foundation of China(41473080);Qingdao National Laboratory for Marine Science and Technology(QNLM2016ORP0210)

Abstract:

The wide occurrence of isoprenoid glycerol dibiphytanyl glycerol tetraethers (isoGDGTs) and its sensitivity to temperature in marine environments proved to be suitable for paleo-climate studies. The Okinawa Trough (OT), under the control of multiple climate patterns and various sediment origins, is a natural laboratory for paleo-climate study since the Holocene. Here, we studied isoGDGTs composition and characteristics, applied outspread tetraether index of tetraethers consisting of 86 carbons (TEXH86 index), tried to identify the source of isoGDGTs, and quantificationally discussed sea surface temperature (SST) of the central OT for the past 8.2 ka BP. By calculating the Methane Index and the branched isoprenoid tetraether (BIT) indexes, we found isoGDGTs mainly came from Thaumarchaeota, and are suitable for TEXH86 appliance. TEXH86 SST of column C14 revealed a range of 21.6-27.2 °C during 8.2 ka BP. Changes in SSTs of the central OT were primarily controlled by the western tropical Pacific Ocean and low-latitude winter insolation. The warming TEXH86 SSTs in the central OT were decoupled from the descending East Asian summer monsoon intensity in the last 8.2 ka BP. The widely recorded cold event at 7.4-6.6 ka BP was magnified in GDGTs related SST. We attributed it to the well-known Kikai-Akahoya tephra (~7.3 ka BP).

Key words: Isoprenoid glycerol dibiphytanyl glycerol tetraethers (isoGDGTs), TEXH86 proxy, sea surface temperature, the central Okinawa Trough

CLC Number: 

  • P532