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The Geochemistry of the Early Cretaceous Red and Green Mudstones, Liupanshan Group, Liupanshan Area and Its Implications on the Climate

Zhang Wenfang, Dai Shuang, Liu Haijiao, Chen Shiqiang, Zhang Yongquan, Zhang Lili, Zhang Rui, Wang Lubo   

  1. Key Laboratory of Western China’s Environmental Systems, Ministry of Education of China & Research School of Arid Environment and Climate Change, Lanzhou University, Lanzhou〓730000, China
  • Received:2011-10-25 Revised:2012-05-25 Online:2012-11-10 Published:2012-11-10

Zhang Wenfang, Dai Shuang, Liu Haijiao, Chen Shiqiang, Zhang Yongquan, Zhang Lili, Zhang Rui, Wang Lubo. The Geochemistry of the Early Cretaceous Red and Green Mudstones, Liupanshan Group, Liupanshan Area and Its Implications on the Climate[J]. Advances in Earth Science, DOI: 10.11867/j.issn.1001-8166.2012.11.1236.

Cretaceous is a typical “greenhouse” period close to the present day. Therefore, it is of great significance to carry out research on its climate change for understanding today’s pattern of climate and environment. In this study, analysis of the elements geochemistry of the Early Cretaceous red and green mudstones of the middle segment of Liwaxia formation, Liupanshan Group in the Liupanshan basin, shows that a majority of the elements are almost concordantly varied between two kinds of mudstones when compared with that of the global average shale. In addition, the Chemical Index of Alteration (CIA) are slightly low (CIA averaged for red and green mudstone is 66.3% and 65.5%, respectively), indicating that both their weathering degree are approximately in lowintermediate level. The result of the A-CN-K diagram plot suggests that both their original rock was the same (largely Hercynian granite). The color differences between the two kinds of mudstones are predominately controlled by the climate change. The variation of the proxies such as CaCO3(wt%), (CaO+Na2O+K2O)/Al2O3, TFeO/Mn, Ti/Sr, Rb/Sr and Sr/Ba proposes that the red mudstone form in the relative wet and oxidation circumstances, whereas the green mudstone in the relative dry and reduction.

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