Funding for this research was provided by:
National Natural Science Foundation of China (41772056, 41390445)
Youth Innovation Promotion Association of the Chinese Academy of Sciences (2018090)
Division of Earth Sciences (EAR-1650329)
Received: 19 June 2019
Accepted: 17 December 2019
First Online: 24 January 2020
: The authors declare no competing interests.