Provenance of the Lower Cambrian Khewra Sandstone: Implications for Pan-African Orogeny

Abstract

This study describes the sedimentological aspects of the Lower Cambrian Khewra Sandstone, along with its lithostratigraphic correlation of globally distributed coeval red sandstones to decipher the imprints of Pan-African Orogeny. Despite the economic significance of Khewra Sandstone, the understanding of its environment of deposition, provenance and lower contact with the suite of igneous body namely Khewrite is poor. The Khewra Sandstone is an allostratigraphic unit bounded by unconformities. The upward coarsening sequence with abundant sedimentary structures and varying sedimentological properties of the topmost bed suggest that the Khewra Sandstone is tempestites deposited under fluvio-deltaic depositional environment. This sandstone is dominated by subarkoses, feldspathic litharenites and sublitharenites which were derived from the craton interior to recycled orogen provenance during the Pan-African orogeny under humid to semi-humid paleoclimatic conditions. The plutonic to metamorphic characteristics of framework grains suggest that the Bundlekhand Craton, Delhi Fold Belt and Aravalli Orogen rocks were the primary provenances. The lower and middle parts of the Khewra Sandstone are significantly affected by diagenesis while the diagenetic action in upper part is negligible and it acts as a potential hydrocarbon reservoir rock. The lithostratigraphic correlation suggests a worldwide series of rifting events before the deposition of Khewra Sandstone and the presence of Khewrite at lower contact marks a similar rifting event on the Indian plate.