GEOCHEMISTRY OF THE AMPHIBOLITES FROM CHENCAI GROUP, ZHEJIANG PROVINCE: IMPLICATIONS FOR THE TECTONIC SETTINGS
Chen Shaohai1, Zhou Xinhua1, Li Jiliang1, Chen Hanlin2, Bao Caomin
1. Laboratory of Lithosphere Tectonic Evolution, Institute of Geology, Chinese Academy of Sciences, Beijing 100029; 2. Department of Earth Sciences, Zhejiang University, Hangzhou 310027; 3. Brigade of Regional Geological Survey, Bureau of Geology and Mineral Resources of Zhejiang, Xiaoshan 311201
The basic assemblage of the amphibolites is consisted of amphibole and plagioclase. Other phases include diopside, biotite, quartz and alkali feldspar. Most amphibolites show an iron-rich trend, typical of the tholeiitic series, few is in calc-alkaline series. The amphibolites are either quartz-normative or olivine-normative. Though in various degrees, LREE-rich is a common feature of the am phibolites from Chencai Group. The petrogeneses of the provenances are also variab le. Nb and Ta anomalies, the slope of the incompatible element distribution patt erns and the correlation between Zr and TiO2 show island arc and oceanic island signatures, suggesting two sources for the amphibolites in Chencai Group. The coexistence of IAB and OIB is indicative of a tectonic setting of ocean-ocean or ocean-continent subduction. The geochemistry of the amphibolite from Badu Group, southwestern Zhejiang province, has an MORB signature, suggesting a different tectonic setting from the central Zhejiang province.
Chen Shaohai,Zhou Xinhua,Li Jiliang et al. GEOCHEMISTRY OF THE AMPHIBOLITES FROM CHENCAI GROUP, ZHEJIANG PROVINCE: IMPLICATIONS FOR THE TECTONIC SETTINGS[J]. Chinese Journal of Geology, 1999, (2): 154-165.