Geochemical records in Pennsylvanian brachiopods in South Guizhou, China: Indicator of shell original chemistry

摘要

It is surprising that a rarely large-scale Pennsylvanian Fomitchevella coral reef present in South Guizhou, China. So the reef-forming environment naturally becomes the object of universal attention. Only brachiopods that are free of any signs of late diagenetic alteration and shared the same living environment with Fomitchevella can be used to extract environmental information of paleoseawater. Although shell preservation state is tested initially using conventional selection criteria, there are still concerns as to whether the selected brachiopod shells of Striatifera striata and Enteletoides shuichengensis do indeed contain original seawater signals. In this study, we assess the shell's original state by evaluating the symmetry of the element distribution in transverse section of dorsal valve. The results show that Fe, Mn, Sr and Ni distributions are nearly symmetrical about a line through the middle of the transect. Symmetry of element distribution pattern is considered an intrinsic ontogenetic property of the brachiopod shell chemistry.