Geochemistry of sandstones from the Miocene Surma Group, Bengal Basin, Bangladesh: Implications for Provenance, tectonic setting and wealthering

Twenty six sandstone samples from six wells penetrating the Miocene Surma Group in the Bengal Basin, Bangladesh, were analyzed by lithium metaborate/tetraborate fusion Inductively Coupled Plasma (ICP) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and by petrographic microscope. The framework grains of the Surma Group sandstones are rich in quartz followed by lithic grains, feldspar and mica (predominantly white mica). The sandstones are dominantly quartzolithic and quartzose one in composition with abundant low-grade metamorphic, sedimentary lithics, low feldspars and little volcanic detritus, indicating that the sands were derived from a quartzose recycled orogen province. The Surma Group sandstones have moderate to high SiO2 contents (64-85%; on average 77%), TiO2 concentrations averaging 0.5%, Al2O3 contents of about 8.4%, and Fe2O3 (total…