Author(s)

Chunyan Yao, Weimin Guo, Junan Liu, Hanwu Li

Nanjing Center, China Geology Survey, Nanjing, China.

The early Cambrian carbonaceous shale and laminated chert-phosphorite assemble (the black rock series) are widespread at the northwest margin of the Tarim Basin, Northwest China. In combination with previously reported data, we present stable molybdenum isotope (δ^98/95Mo), TOC, and redox-sensitive trace elements to evaluate the sedimentary conditions in early Cambrian water column during the deposition of the black rock series in the Tarim Basin. Redox variation was documented based on enrichment factors (Mo_EF, V_EF, and U_EF) and redox-sensitiv elements ratios (Ni/Co, V/Cr, δU), etc. During the early Cambrian, there was transgressive event, and the sea level continues to rise. In the basal Cambrian, laminated chert-phosphorite assemble with low TOC concentrations suggest the oxic sedimentary condition in a restricted basin. Light Mo isotope values and redox sensitive elements enrichment in the carbonaceous shale layer indicate lack oxygenic sedimentary condition, and was suboxic/anoxic conditions during the transgressive phase. The hydrothermal fluids from the open ocean affected the whole deposition process of the black rock series.

Molybdenum Isotope, Trace Element, Paleo-Environment, Early Cambrian, Tarim Basin

Yao, C. , Guo, W. , Liu, J. and Li, H. (2017) Multiple Proxies on the Paleoenvironment of the Early Cambrian Marine Black Rock Series in the Tarim Basin, NW China: Molybdenum Isotope and Trace Element Evidence. International Journal of Geosciences, 8, 965-983. doi: 10.4236/ijg.2017.88055.