Geochemistry of Carboniferous shales of the Sardar Formation, east central Iran: Implication for provenance, paleoclimate and paleo-oxygenation conditions at a passive continental margin

Abstract

The Sardar Formation (Carboniferous) has a lithological variation that is characterized by sandstone, shale and limestone members. Shales of the Sardar Formation from the east central Iran have been analyzes for major elements and a number of trace elements. The shales of Sardar Formation are rich in quartz minerals and clay minerals of the bulk minerals. Clay minerals of shales are composed of illite, Kaolinite and slightly montmorillonite. SiO2 versus K2O/Na2O diagram shows these shales plotted in the passive continental margin or cratonic field. Geochemical data suggest high acidic source rocks similar to granite and intermediate igneous rocks. CIA and ICV suggest semi-humid climatic conditions during depositions and indicate that high chemical weathering in the source area. The geochemical parameters such as V/Cr, Ni/Co and Cu/Zn ratios indicate that these shales were deposited in oxic environment.