Provenance, tectonic setting and geochemical maturity of the Early Miocene Pyawbwe Formation, Sakangyi –Thayet Area, Pyay Sub-Basin, Myanmar

The best exposed Early Miocene (820m.thick.) shales and interbedded silty sandstones beds of the Pyawbwe Formation at Sakangyi-Thayat area are investigated geochemically by using Siemens SRS-X Ray 303 AS XRF Spectrometer. Major and some trace element concentrations have been determined to achieve their provenance, tectonic setting paleoweathering, paleoclimate and sedimentation characteristics. The geochemistry of sediments is particularly valuable in the study of fine-grained rocks that are difficult to characterize through petrographic studies. Geochemical data revealed that the felsic granitic plutonic provenance of moderate relief of arc massif exposed on tectonically calm continental margin which is probably the Shan- Thai continental block and northeastern Myanmar. Average values of both Chemical Index of weathering (CIW) and Chemical Index of Alteration (CIA) (77.4 and 67.3 respectively) suggest a moderately chemical weathering condition prevailed during transportation and deposition on passive shallow margin as progressive mature sediments.