Projects per year
Abstract
Recent advances in radiometric dating have enabled independent investigation
into monsoon variations. In this study, summer monsoon pedogenesis proxies (CaCO3 and magnetic susceptibility) have been analysed by optically stimulated luminescence (OSL) age for five loess-palaeosol sections over the Chinese Loess Plateau. The use of CaCO3 is complicated by the multiple influences on its variation. However, changes in magnetic susceptibility can be used as a proxy for summer monsoon induced pedogenesis. The data suggest that the summer monsoon in north-central China is not prone to high frequency shifts, although abrupt transitions occur. The overall patterns show general decreasing trends from c. 50 to 18 ka. However, between 9 and 6 ka, magnetic susceptibility increases abruptly and dramatically at the sites. These findings suggest that the Holocene ‘optimum’ in the region may be a more recent phenomenon than previously suggested, and that this summer monsoon intensity increase significantly post-dates the insolation peak occurring at 11.5 ka. An apparent close correspondence to ice volume is suggested to be a consequence of forcing via atmospheric circulation. Independently dated records that employ high sampling resolution can be used to test this hypothesis, together with suggestions over the apparent lag between insolation forcing and monsoon response.
into monsoon variations. In this study, summer monsoon pedogenesis proxies (CaCO3 and magnetic susceptibility) have been analysed by optically stimulated luminescence (OSL) age for five loess-palaeosol sections over the Chinese Loess Plateau. The use of CaCO3 is complicated by the multiple influences on its variation. However, changes in magnetic susceptibility can be used as a proxy for summer monsoon induced pedogenesis. The data suggest that the summer monsoon in north-central China is not prone to high frequency shifts, although abrupt transitions occur. The overall patterns show general decreasing trends from c. 50 to 18 ka. However, between 9 and 6 ka, magnetic susceptibility increases abruptly and dramatically at the sites. These findings suggest that the Holocene ‘optimum’ in the region may be a more recent phenomenon than previously suggested, and that this summer monsoon intensity increase significantly post-dates the insolation peak occurring at 11.5 ka. An apparent close correspondence to ice volume is suggested to be a consequence of forcing via atmospheric circulation. Independently dated records that employ high sampling resolution can be used to test this hypothesis, together with suggestions over the apparent lag between insolation forcing and monsoon response.
Original language | English |
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Title of host publication | Monsoon Evolution and Tectonic-Climate Linakge in Asia |
Editors | Peter D. Clift, Ryuji Tada, Hongbo Zheng |
Publisher | Geological Society of London Special Publication |
Pages | 87-108 |
Number of pages | 21 |
Volume | 342 |
ISBN (Print) | 1-86239-310-3 |
DOIs | |
Publication status | Published - 27 Sept 2010 |
Projects
- 1 Finished
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Investigating the East Asian monsoon through geochronological, geochemical and magnetic fabric etc in China
Stevens, T. (PI) & Lu, H. (CoI)
1/09/08 → 31/08/09
Project: Research