Generic Provenance, Tectonics and Petrofacies Evolution of Sandstones, Jaisalmer Formation (Middle Jurassic), Rajasthan

Petrofacies of the Middle Jurassic Jaisalmer sandstones has been analysed in the light of known geotectonic evolution of the Precambrian Aravalli-Delhi fold belt. Various factors responsible for modification of the original detrital composition of the sandstones have been critically examined. In addition, heavy minerals have also been studied to strengthen the interpretation of the provenance.

The Jaisalmer sandstone petrofacies plot in the 'mature craton interior field' rather than the expected 'recycled orogen' and/or 'basement uplift provenance', in accordance with the recent models of orogenic evolution of the Aravalli- Delhi fold belt. The granite-gneiss from the basement uplift as well as the metamorphic and sedimentary rocks of recycled orogen (Aravalli and Delhi Supergroups) acted as the provenance for the Jaisalmer sandstones. The first cycle and recycled detritus were further intensely modified as a result of weathering under warm humid climate and transport before burial, thereby providing mineralogical maturity to the Jaisalmer sandstones.