Pliocene-Quaternary crustal melting in central and northern Tibet and insights into crustal flow.
There is considerable controversy over the nature of geophysically recognized low-velocity-high-conductivity zones (LV-HCZs) within the Tibetan crust, and their role in models for the development of the Tibetan Plateau. Here we report petrological and geochemical data on magmas erupted 4.7-0.3 Myr ago in central and northern Tibet, demonstrating that they were generated by partial melting of crustal rocks at temperatures of 700-1,050 °C and pressures of 0.5-1.5 GPa. Thus Pliocene-Quaternary melting of crustal rocks occurred at depths of 15-50 km in areas where the LV-HCZs have been recognized. This provides new petrological evidence that the LV-HCZs are sources of partial melt. It is inferred that crustal melting played a key role in triggering crustal weakening and outward crustal flow in the expansion of the Tibetan Plateau.
State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.|CAS Center for Excellence in Tibetan Plateau Earth Sciences (CETES), Beijing 100101, China.
Qiang
Q
Wang
School of Earth Sciences, University of Bristol, Wills Memorial Building, Queens Road, Bristol BS8 1RJ, UK.|Department of Earth and Environmental Sciences, University of St Andrews, North Street, St Andrews KY16 9AL, UK.
Chris J
CJ
Hawkesworth
School of Geosciences, The University of Sydney, Sydney, New South Wales 2006, Australia.
Derek
D
Wyman
Institute of Earth Sciences, Academia Sinica, Nangang, Taipei 11529, Taiwan.|Department of Geosciences, National Taiwan University, Taipei 10617, Taiwan.
Sun-Lin
SL
Chung
Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China.
Fu-Yuan
FY
Wu
Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China.
Xian-Hua
XH
Li
ARC Centre of Excellence for Core to Crust Fluid Systems (CCFS) and the Institute for Geoscience Research (TIGeR), Department of Applied Geology, Curtin University, Perth, Western Australia 6845, Australia.
Zheng-Xiang
ZX
Li
State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
Guo-Ning
GN
Gou
State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
Xiu-Zheng
XZ
Zhang
State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
Gong-Jian
GJ
Tang
State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
Wei
W
Dan
State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
Lin
L
Ma
State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
Yan-Hui
YH
Dong