[SMP40-P09] Sr isotope chemostratigraphy of metacarbonate rocks from East Gondwana; Implications for depositional environments and correlations
Keywords:Sr isotopes, Gondwana, Chemostratigraphy
Taking advantage of the characteristics of metacarbonate rocks to understand the depositional history of oceanic basins, we compile data from several terrains in the EAAO belt and attempt to correlate between the terrains. Pure carbonate samples that were least influenced by alteration (that consist of calcite/ dolomite mineral or only with minor amounts of calc-silicate minerals) were selected for this purpose. Based on thin section observation, oxygen and carbon isotopic composition and trace and rare earth element patterns we selected the purest samples for Sr isotope analysis. The δ18O values of meta-carbonate rocks above 20 ‰ and those with flat REE patterns were the best candidates for Sr isotope analysis.
The Sr isotopic compositions was compared with standard late Proterozoic Sr isotope chemostratigraphic curve, which suggest apparent depositional ages between 900 Ma to 660 Ma. Comparable Neoproterozoic sedimentation histories were obtained from the Highland Complex, Sri Lanaka, Madurai Block, southern India, and Dronning Maud Land, East Antarctica. In this presentation we discuss the possible correlation between different blocks within the East Gondwana ensemble.