title: Multiple climate cooling prior to Sturtian glaciations: evidence from chemical index of alteration of sediments in South China.
abstract: Investigation of climatic conditions prior to the Sturtian glaciations is critical to understanding the trigger mechanism for the series of Neoproterozoic global glaciations. In this study, we report high-resolution chemical index of alteration (CIA) records in the sediments of South China prior to the Sturtian glaciation (820~720 Ma). Our results showed there occurred multiple climate cooling before the Sturtian glaciations in South China: (1) a series of episodic and possibly global climate cooling periods from ca. 750 Ma to 725 Ma, which also caused some diachronous regional glaciations; (2) a permanent climate cooling period between ca. 800 Ma and 770 Ma, probably contemporaneous to the global "Bitter Springs stage" δ(13)C negative excursion; (3) a climate cooling period between ca. 815 Ma and 810 Ma. The three stages of climate cooling are also supported by their correspondence to previously reported extremely low δ(18)O records of igneous/metamorphic minerals from South China. These climate cooling periods also coincide with the magmatism and rifting events in South China. We argue that tectonic movements were the primary control on the climate cooling before the Neoproterozoic global glaciations.
authors.affiliation: CAS Key Laboratory of Crust-Mantle Materials and Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China.
authors.forename: Lianjun
authors.initials: L
authors.lastname: Feng
authors.affiliation: Guizhou Geological Survey, Guiyang 550002, China.
authors.forename: Dingbiao
authors.initials: D
authors.lastname: Lu
authors.affiliation: State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China.
authors.forename: Qirui
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: 1] Astromaterials Research and Exploration Science (ARES), Johnson Space Center, NASA, Houston, TX. 77058, USA [2] Department of Geology and Geophysics, Louisiana State University, Baton Rouge, LA. 70803.
authors.forename: Tao
authors.initials: T
authors.lastname: Sun
authors.affiliation: 1] State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China [2] State Key Laboratory of Continental Dynamics, Northwest University, Xi'an 710069, China.
authors.forename: Xuelei
authors.initials: X
authors.lastname: Chu