The Pleistocene vermicular red earth in South China signaling the global climatic change: The molecular fossil record

Abstract

The trace molecular fossils identified in the Pleistocene vermicular red earth by using the gas chromatography-mass spectrometry (GC/MS) analysis include n -alkanes, n -alkanoic acids, n -alkanols and n -alkan-2-ones. The variations of the n -alkane parameters appear to bear significant climate information, in striking contrast to the oxygen-bearing molecules ( n -alkanoic acids and n -alkanols) believed to be more easily reworked by post-depositional processes. Of importance in paleoclimate reconstruction are the ratios of C 27 /C 31 n -alkane indicative of the replacement of woody plants by grassy vegetation, and C 15—21 /C 22—33 n -alkane representative of the relative abundance between microorganisms and higher plants. The profile trends of the two n -alkane ratios are comparable to the marine oxygen isotope record among stages 4—20. These molecular fossil records implicate that the Pleistocene vermicular red earth widespread in South China was formed in coupling to the global climatic change and could be an important climate carrier.