Century-to-millennial scale climatic variability in Lake Malawi revealed by isotope records

被引:36
作者
Barker, Philip A. [1 ]
Leng, Melanie J.
Gasse, Francoise
Huang, Yongsong
机构
[1] Univ Lancaster, Dept Geog, Lancaster Environm Ctr, Lancaster LA1 4YB, England
[2] British Geol Survey, NERC, Isotope Geosci Lab, Keyworth NG12 5GG, Notts, England
[3] Univ Nottingham, Sch Geog, Nottingham NG7 2RD, England
[4] Univ Aix Marseille 3, CNRS, UMR 6635, CEREGE, F-13545 Aix En Provence 04, France
[5] Brown Univ, Dept Geol Sci, Providence, RI 02912 USA
基金
英国自然环境研究理事会;
关键词
isotopes; oxygen; diatoms; deuterium; palmitic acid; Malawi; palaeoclimate;
D O I
10.1016/j.epsl.2007.06.010
中图分类号
P3 [地球物理学]; P59 [地球化学];
学科分类号
0708 ; 070902 ;
摘要
Diatom-based oxygen isotope data (delta O-18(diatom)) from Lake Malawi show multi-centennial scale wet-dry intervals spaced approximately every 2.3 ka throughout a 25 ka sequence. The delta O-18(diatom) record is supported by a lower resolution deuterium (delta D-pa)isotope curve derived from palmitic acid. We interpret these isotope data in terms of major shifts in precipitation and evaporation moderated by seasonal controls on the host organisms. Dry periods marked by relatively positive isotope values, represent the extension of abrupt Holocene events noted from northern and equatorial Africa to 10-15 degrees S. These events in Lake Malawi correspond to cool episodes in Greenland, thereby demonstrating teleconnections generated by meridional temperature gradients. Sea surface temperatures are likely to be the primary transmitter of deglacial climate changes, although trade wind strength and direction is critical in controlling precipitation patterns in tropical regions. Conversely, the global hydrological cycle, driven by low latitude regions represents an important positive feedback amplifying deglacial processes. (C) 2007 Published by Elsevier B.V.
引用
收藏
页码:93 / 103
页数:11
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