Rock Magnetic and Pedogenic Studies of the Paleoclimate Record of Loess Deposits

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Sequences of paleosols and loess units throughout the world have been interpreted as geologic records of terrestrial climate change. Of particular significance has been the discovery of a correlation between variations in the magnetic susceptibility in the Chinese loess sequence and the oxygen isotope record of the deep sea. Using an approach that combines rock magnetic measurements with a soil chemistry extraction procedure, we have obtained new data that challenges previous interpretations about the origin and nature of the magnetic susceptibility signal. In this proposal we request support for a comprehensive, interdisciplinary study of the rock magnetism and soil chemistry of paleosol/loess sequences in China and elsewhere. The goals of our study are 1) to complete our determination of the general characteristics of the magnetic susceptibility signal using a combination of rock magnetic and soil chemistry techniques, 2) to compare our rock magnetic analyses of the Chinese loess/paleosol sequence with similar analyses of loess/paleosols sequences in Alaska and New Zealand, and 3) to obtain complete soil descriptions and detailed profiles of soil chemistry and rock magnetic properties from selected loess and paleosols units. The work for this last objective will be done in close collaboration with Chinese colleagues.