Petrography of the Bajocian Sandstone of Joyan Member, Jaisalmer Basin, Western Rajasthan: Implications for Provenance and Basin Evolution

Abstract

Detailed petrographic, dense minerals and petrofacies investigations were performed on forty nine medium- to finegrained, well-cemented and moderately to well-sorted sandstone samples from the Joyan Member of the Jaisalmer Formation. The grains are sub-angular to sub-rounded in shape, with some well-rounded quartz grains. The framework composition of sandstone consists mostly of monocrystalline and polycrystalline quartz, low-to high-grade metamorphic and sedimentary rock fragments, as well as subordinate feldspar with low plagioclase to total feldspar ratios and accessory minerals. Petrographic investigations reveal that sandstones from the Joyan Member of the Jaisalmer Formation are sublitharenite to litharenite. The sandstone composition suggests that the detritus are derived from the metamorphic, plutonic-volcanic felsic, and recycled sedimentary rocks. Dense mineral analyses also confirm the possibility of mixed provenance for the Joyan Member Sandstone. The sandstone petrofacies indicates their derivation from cratonic interiors, as well as recycled orogenic and quartzose recycled provenances under humid climatic conditions. The petrographic, sedimentological, and dense mineral analyses in agreement with palaeocurrent data suggest that the Joyan Member Sandstone was primarily derived from Erinpura-Godhra-Mount Abu-Sirohi (Balda) granites and Malani volcanics, with a contribution from Archean Aravalli (Berach) granitoids and Aravalli and Delhi orogens. The shift in sediment supply from Aravalli (Berach) granitoids and Aravalli and Delhi orogens to Erinpura-Godhra-Mount Abu-Sirohi (Balda) granites and Malani volcanics supports sedimentation in a tectonically active basin.