Provenance changes of eolian dust at Lingtai section in the Chinese Loess Plateau since 7 Ma and its implication for desert development in East Asia Y. Isozaki1, R. Tada1, Y. Sun2, K. Nagashima3, H. Zheng4, S. Toyoda5, and A. Tani6 1Department of Earth and Planetary Science, University of Tokyo, Tokyo, Japan 2Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, China 3Japan Agency for Marine-Earth Science and Technology, Yokosuka, Japan 4School of Ocean and Earth Science, Tongji University, Shanghai, China 5Department of Applied Physics, Okayama University of Science, Okayama, Japan 6Department of Earth and Space Science, Osaka University, Osaka, Japan
Abstract. It is suggested that the uplift of Himalaya-Tibetan Plateau enhanced
interior aridity in East Asia and resulted in development of middle latitude
gobi and sandy deserts and accumulation of the eolian sediments in the
Chinese Loess Plateau. Therefore, estimation of the provenance for eolian
sediments in the Chinese Loess Plateau is critical to reconstruct the
environmental changes in East Asia and their relation to the
Himalaya-Tibetan Plateau uplift.
We recently developed a new provenance tracing method by using a combination
of Electron Spin Resonance (ESR) signal intensity and Crystallinity Index
(CI) of quartz, and demonstrated that fine fraction of the surface sediments
from nine major deserts in East Asia could be distinguished one another on
the ESR signal intensity versus CI diagram. Here, we measured ESR signal
intensity and CI of quartz in fine fractions of samples covering the last 7 Ma
obtained from Lingtai section in the central Chinese Loess Plateau, and
compared the results with those of the surface samples from nine major
deserts in East Asia.
The results suggest that the provenance of fine fraction of the eolian
sediment in Lingtai section changed at 4.3, 2.1, 1.4, 1.1, 0.8 and 0.4 Ma.
During 7 to 4.3 Ma, the dust might be have been supplied from Precambrian to
Paleozoic metamorphic and granitic rocks and granite exposed in the present
central to eastern part of the Tian Shan Mountains. The contribution from
the Taklimakan desert appeared at 4.3 Ma, increased drastically at 1.1 Ma,
and persisted till 0.8 Ma, whereas the main source of detrital material to
the Taklimakan desert might have changed from eastern part of the Kunlun and the Altyn
Mountains to western part of the Kunlun and the Tian Shan Mountains. During
0.8 to 0.4 Ma, contribution from the Badain Juran desert gradually
increased. Finally, contribution from the Tengger desert appeared from 0.4
to 0 Ma. Together with tectonic evidences from literatures, the provenance
changes from 4.3 to 0.8 Ma seem to reflect uplift of the Tian Shan and the
Kunlun Mountains and consequent formation of the Taklimakan desert, whereas
the change at 0.4 Ma may reflect uplift of the Qilian Mountains although
formation of mountain glaciers could be an alternative possibility. These
provenance changes will provide important constraints not only on the
development of arid areas and evolution of monsoon but also on the uplift
and erosion of mountains in East Asia.
Citation: Isozaki, Y., Tada, R., Sun, Y., Nagashima, K., Zheng, H., Toyoda, S., and Tani, A.: Provenance changes of eolian dust at Lingtai section in the Chinese Loess Plateau since 7 Ma and its implication for desert development in East Asia, Clim. Past Discuss., 4, 335-374, doi:10.5194/cpd-4-335-2008, 2008.