Geochemical characteristics of the Permian sedimentary rocks from Qiangtang Basin: Constraints for paleoenvironment and paleoclimate

摘要

Qiangtang Basin is expected to become important strategic petroleum exploitation area in China. However, little research has been done on the Permian strata in this area. This paper presents Lower Permian Zhanjin Formation geochemical data from the Jiaomuri area, reconstructing the paleo-depositional environment and providing information for further petroleum exploration. The geochemical characteristics of 19 samples were investigated. These geochemical samples show a developed mud flat characteristic with light rich clay content. The geological data were used to constrain the paleoredox environment, which proved that these sediments were deposited mainly beneath a slightly oxic water column with relatively low paleoproductivity as evidenced by the P/Ti (mean of 0.07) and Ba/Al (mean of 20.5). Palaeoclimate indexes such as the C-value (0.24-1.75) and Sr/Cu (1.28-11.58) reveal a humid climatic condition during Zhanjin Formation sediment deposition. The.(La)(N)/omega(Yb)(N) ratio values indicate a fast sedimentary rate during the deposition period.