Weathering histories of Chinese loess deposits based on uranium and thorium series nuclides and cosmogenic {sup 10}Be
- Scripps Institution of Oceanography, La Jolla, CA (United States)
- Institute of Geology, Beijing (China); and others
The long, continuous deposition of dust in the Chinese loess plateau offers an unique opportunity to study the nature of soil weathering in a wide range of climatic conditions. In this paper we report on measurements of concentrations of U- and Th-series nuclides and of major cations in 150 loess and paleosol samples from five sites, going back 2.5 Ma. Using the results for {sup 10}Be concentrations in these soils, we determined the absolute amounts of water added to several soil units and obtained: (1) first-order leaching constants for U and several cations and (2) the compositions of the soils contributing to the dust-source regions and of the dust at deposition. Further, based on analyses of {sup 230}Th in soils deposited in the past ca. 140 ka, we determined when the soils weathered in the source regions. We conclude that most of the weathering in the dust-source regions may have occurred during the interglacials. 34 refs., 8 figs., 2 tabs.
- OSTI ID:
- 576328
- Journal Information:
- Geochimica et Cosmochimica Acta, Vol. 61, Issue 24; Other Information: PBD: Dec 1997
- Country of Publication:
- United States
- Language:
- English
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