GEOCHEMICAL AND PETROGRAPHIC ANALYSIS OF NIMAR - SANDSTONES, CENTRAL INDIA AND ITS IMPLICATIONS

Abstract

Present study is confined to Nimar Sandstone which is found between metamorphic rocks and limestone, around the Bagh township. It comprises of sandstones, shales and locally developed conglomerate. Nimar Sandstones is important as it bears the evidences of Mesozoic marine transgression related to the formation of west coast in India. This formation uniquely bears evidences of shift in sedimentation from continental fluvial to marine condition through a broad phase of fluvio-marine interaction. Combination of field and Petrographic studies indicate that Nimar Sandstone mainly consists of quartz arenites deposited in an overall transgressive system. Geochemical analysis in terms of major oxides and trace elements of sandstones and shale samples from different stratigraphic horizons within Nimar Sandtones will be carried out to understand the palcocl imatic-paleoenvironmental-paleotectonic controls on sedimentation in a fluvio-marine interactive system during the Mesozoic marine transgression in peninsular India. A remarkable variation of geochemical properties has been found in study areas through X-Ray Fluroscence ( XRF ) analysis. Provenance studies from analysis of major oxides and trace elements indicates that Nimar Sandstone sediments were derived from a felsic source that is granitic to granodioritic in nature. These sediments belong to a source of Passive Continental Margin tectonic setting. The sediments have been intensely weathered and have undergone one or more phases of recycling.