Geochemistry of the Conglomerates and the Tectonic Setting of Their Provenance in Fenghuangtai Formation in the North Margin of the Dabie Mountains
LI Shuang-ying 1 LI Ren-wei 2 WANG Dao-xuan 1 LIU Yin 1 MENG Qing-ren 2 YUE Shu-cang 1 JIN Fu-quan 1(Department of Natural Resources and Environmental Science, Hefei University of Technology, Hefei 230009) 2(Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029)
Based on the study of geochemistry of the conglomerates of eclogites, hornblende schist, plagiognesis etc. in Fenghuangtai and Maotangchang Formations located in the north margin of the Dabie Mountains, concentrations of SiO_ 2 are 43.31% ~ 57.35% in conglomerates, and their protoliths consist of mainly volcanic rocks of basalt, basaltic andesite, basalatite, secondly intruded rocks of anorthosite and diabase-prophyrite etc. They are characterized as enrichment in LILE, notable Nb-Ta depleted through, and Ti depleted in comparison with primitive mantle. This indicates that they formed in an SSZ type island-arc setting. There was a relation between protoliths of the gravels and magnesioferrite and super magnesioferrite belt, gneiss etc. of north Dabie complex (paleo-island arc root belt). The conglomerates may come from the upper of the volcanic arc, not paleo-island arc root belt being suffered denudation now.