CHENG Cheng1, LI Shuang-ying1*, ZHAO Da-qian2, YAN Ling3
1. School of Resources and Environmental Engineering, Hefei University of Technology, Hefei 230009, China;
2. Shangdong Gold Nonferrous Metal Mining Group Co., LTD, Jinan 250000, China;
3. Seismological Bureau, Anhui Province, Hefei 230031, China
Abstract: To discuss the origin and sedimentary background of chert in South China, we took the bedded cherts in Gufeng and Dalong Formations which locate in the northern margin of the Yangtze block as examples. In this study, we collected extended literature data about these two formations and systematically analyzed major, trace and rare earth elements contents of cherts collected from the formations. The average values of Al/(Al+Fe+Mn) and Si/(Si+Al+Fe) ratios for Gufeng and Dalong Formations are 0.48 and 0.97, and 0.57 and 0.91, respectively, which combined with plots of Al-Fe-Mn of cherts indicated that they are mainly biogenic cherts. The average values of Ce/Ce*,(La/Ce)N and (La/Yb)N for Gufeng and Dalong Formations are 0.86, 1.58 and 1.27 and 0.75, 1.52 and 1.46, respectively, which combined with diagrams of sedimentary environments suggested that they were mainly deposited at continental margins. According to their origin and sedimentary background, we concluded that formations of the cherts were more likely associated with activities of upwelling. The hydrothermal chert and chert influenced by hydrotherm tended to distribute along the syndepositional faults in some areas, which may implied that syndepositional faults provided channels for the hydrotherms.
Keywords: chert geochemistry upwelling hydrothermal deposit Middle-Upper Permian northern margin of the Yangtze Block
*Corresponding Author, E-Mail: lsysteven@126.com
Bulletin of Mineralogy, Petrology and Geochemistry Vol. 34, No.1, 2015, page 155-166
