Petrogenesis and Geotectonic Significance of Early-Neoproterzoic Olivine-Gabbro within the Yangtze Craton: Constrains from the Mineral Composition, U-Pb Age and Hf Isotopes of Zircons  

作　　者：Xingfu Jiang Songbai Peng Timothy M.Kusky Lu Wang Hao Deng 

机构地区：[1]School of Earth Sciences, East China University of Technology [2]School of Earth Sciences, China University of Geosciences [3]Center for Global Tectonics, China University of Geosciences [4]State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences [5]Three Gorges Center for Geohazard, Ministry of Education, China University of Geosciences

出　　处：《Journal of Earth Science》2018年第1期93-102,共10页地球科学学刊（英文版）

基　　金：support by the National Natural Science Foundation of China (No. 41272242);the Education Department of Jiangxi Province (No. GJJ150562);the East China University of Technology (No. DHBK2015321)

摘　　要：The olivine-gabbroic rocks located at the Huangiing anticline within the Yangtze Craton are dated at circa 857-854 Ma by LA-ICP-MS method. The rocks belong to the sub-alkaline series and consist of pyroxene （35%-40%）, plagioclase （40% -45%）, olivine （8%-10%） and spinel （3%-5%）. Olivine has Fo values of 73-83 that is classified as chrysolite. Pyroxene has relative low contents of FeO （6.60 wt.%-8.23 wt.%） but high CaO （20.23 wt.%-21.25 wt.%） contents, however, plagioclase has high A1203 （31.78 wt.%o-32.37 wt.%）, CaO （16.08 wt.%-16.25 wt.%） and An （79-80） values, but low Na20 contents （1.95 wt.%-2.11 wt.%）. Spinel are magnesioferrite with characteristics of high contents of MgO （13.65 wt.%- 13.68 wt.%）, FeO （23.27 wt.%-23.40 wt.%） and A1203 （62.43 wt.%-62.74 wt.%）. Chemical compositions of these minerals are similar to those of gabbro rocks that were formed in the post-orogeny environment. The olivine-gabbro samples have negative zircon eHf values （-16.57±0.47） that resemble the mafic rocks in the same region, indicating that they are derived from the extremely enriched mantle source. On the compilation of documented Neoproterozoic mafic rocks in the Yangtze Craton, it is proposed that the mantle in the northern Yangtze Craton has experienced different degrees enrichment during the Neoproterozoic.The olivine-gabbroic rocks located at the Huangiing anticline within the Yangtze Craton are dated at circa 857-854 Ma by LA-ICP-MS method. The rocks belong to the sub-alkaline series and consist of pyroxene （35%-40%）, plagioclase （40% -45%）, olivine （8%-10%） and spinel （3%-5%）. Olivine has Fo values of 73-83 that is classified as chrysolite. Pyroxene has relative low contents of FeO （6.60 wt.%-8.23 wt.%） but high CaO （20.23 wt.%-21.25 wt.%） contents, however, plagioclase has high A1203 （31.78 wt.%o-32.37 wt.%）, CaO （16.08 wt.%-16.25 wt.%） and An （79-80） values, but low Na20 contents （1.95 wt.%-2.11 wt.%）. Spinel are magnesioferrite with characteristics of high contents of MgO （13.65 wt.%- 13.68 wt.%）, FeO （23.27 wt.%-23.40 wt.%） and A1203 （62.43 wt.%-62.74 wt.%）. Chemical compositions of these minerals are similar to those of gabbro rocks that were formed in the post-orogeny environment. The olivine-gabbro samples have negative zircon eHf values （-16.57±0.47） that resemble the mafic rocks in the same region, indicating that they are derived from the extremely enriched mantle source. On the compilation of documented Neoproterozoic mafic rocks in the Yangtze Craton, it is proposed that the mantle in the northern Yangtze Craton has experienced different degrees enrichment during the Neoproterozoic.

关 键 词：Neoproterozoic olivine-gabbro Huangling anticline post-orogeny environment Yangtze Craton. 

分 类 号：P2[天文地球—测绘科学与技术]