Clay mineralogy of the Zhada sediments : Evidence for climatic and tectonic evolution since ~9 Ma in Zhada, southwestern Tibet
Hong, Hanlie (China University of Geosciences. Faculty of Earth Sciences)
Wang, Chaowen (China University of Geosciences. Faculty of Earth Sciences)
Zeng, Kefeng (China University of Geosciences. Faculty of Earth Sciences)
Zhang, Kexin (China University of Geosciences. Faculty of Earth Sciences)
Yin, Ke (China University of Geosciences. Faculty of Earth Sciences)
Li, Zhaohui (University of Wisconsin-Parkside. Geosciences Department)

Data:	2012
Resum:	The clay mineralogy of the Zhada sediments was investigated, using X-ray diffraction and scanning electron microscopy, to obtain a better understanding of climatic change and uplift of the Himalayas in the Zhada region of Tibet. The sediments of Zhada basin in the late Miocene to Pliocene consist of lacustrine and fluvial deposits >800 m thick and can be subdivided into five clay assemblage zones based on their clay-mineral composition. The upward zonation is as follows: (1) smectite-kaolinite; (2) illite-chlorite; (3) chlorite-illite-kaolinite; (4) illite-chlorite; and (5) smectite, illite, and kaolinite. The ratio of chlorite + illite to kaolinite + smectite (Ch+I/K+S) and the Kübler index indicate a warm and humid climate from 9. 5 to 8. 4 Ma, a cold and dry climate from 8. 4 to 7. 2 Ma, a warm and seasonal arid climate from 7. 2 to 4. 5 Ma, a cool and humid climate from 4. 5 to 3. 6 Ma, and a warm and seasonally humid climate from 3. 6 to 3. 0 Ma. Intense fluctuations in the Kübler index and in the quantities of evaporite minerals dolomite, aragonite, and gypsum, during the period 7. 2-4. 5 Ma suggest strong climatic fluctuations between humid and seasonally humid conditions in the Zhada basin. Rapid uplift around the Zhada basin occurred at 8. 4 and 3. 6 Ma, with sharp subsidence at 7. 2 and 4. 5 Ma. Evolution of the climate at Zhada showed a different model from that of global climate change, and tectonics-led climate change was the major contributor to climate evolution in the area.
Drets:	Tots els drets reservats.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Matèria:	Kübler Index ; Paleoclimate ; Tibetan Plateau ; Uplift ; Zhada Basin
Publicat a:	Clays and Clay Minerals, Vol. 60, Núm. 3 (2012) , p. 240-253, ISSN 1552-8367

DOI: 10.1346/CCMN.2012.0600302

14 p, 2.6 MB  Accés restringit a la UAB

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