Carbon and oxygen isotope geochemistry of Neoproterozoic limestones of the Shahabad Formation, Bhima basin, Karnataka, southern India

petrography, major (including four trace elements), stable isotopes (carbon and oxygen), and 87sr/86sr geochemistry of limestones of the shahabad formation, bhima basin, karnataka, southern india are reported. these limestones show a narrow range of δ13c (1.34-1.96) and δ18o ( -6.04 to - 7.61 ) values. the petrographic study reveals the presence of microsparite and micro- and macrostylolites. the δ13c and 87sr/86sr values indicate that these limestones were deposited during the late neoproterozoic age and the δ18 o values also are very similar to the average proterozoic carbonate values. mn and sr concentrations and low mn/sr ratio (<1) together with the stable and radiogenic isotope data suggest that the studied samples are well-preserved or scarcely altered limestones and probably have retained their primary isotopic signatures.