Rock magnetic and grain size evidence for intensified Asian atmospheric circulation since 800,000 years BP Related to Tibetan uplift

Citation
Xm. Fang et al., Rock magnetic and grain size evidence for intensified Asian atmospheric circulation since 800,000 years BP Related to Tibetan uplift, EARTH PLAN, 165(1), 1999, pp. 129-144
Citations number
53
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Earth Sciences
Journal title
EARTH AND PLANETARY SCIENCE LETTERS
ISSN journal
0012-821X → ACNP
Volume
165
Issue
1
Year of publication
1999
Pages
129 - 144
Database
ISI
SICI code
0012-821X(19990115)165:1<129:RMAGSE>2.0.ZU;2-#
Abstract
Paleomagnetic, rock magnetic, and grain size studies of a thick loess seque nce in the West Qin Ling (mountain range) show that loess deposition there began about 800 ka. The data reveal a progressively increasing coarse grain size fraction upwards into the Holocene. The averages of these coarse size fractions are higher than in the central Loess Plateau, which was apparent ly farther from the source area, and slightly lower than those of the weste rn Loess Plateau and the eastern Tibetan Plateau, which were therefore clos er to the source area. The coarsening and source area location suggest (1) that Asian air circulation may have changed and intensified at about 800 ka resulting in dust deposition in West Qin Ling; (2) that dust-carrying wind s were driven not only by the Asian winter monsoon, but included also the w esterlies and a winter monsoon caused by the Tibetan Plateau High, and (3) that intensification of all these air circulation systems continues to the present. Increased elevation of the Tibetan Plateau so that it reached into the cryosphere by about 800 ka and a subsequent persistent uplift of the p lateau may have been the mechanisms to trigger a change and intensify the a ir circulation system. Moreover, this circulation shift and intensification , simultaneous with a shift in Milankovitch periodicity, may have contribut ed to large global climate changes such as the 15% increase in global ice v olume at ca. 800 ka. (C) 1994 Published by Elsevier Science B.V. All rights reserved.