Subsurface sediment accumulation patterns and their relationships with tectonic lineaments in the semi-arid Luni river basin, Rajasthan, Western India

Abstract

Sediment accumulation patterns in the Luni basin have been studied on the basis of tubewell lithologs and Bouguer gravity anomaly profiles. East-West geologic transects using these data reveal several sediment-filled graben depressions, for example, the Digrana-Bhawal graben in the northern part, the Mangta-Sindari, Sindari-Bhimgoda, and Bhimgoda-Juna Motisara grabens in the central part; and the Dungari-Ratanpura and Ratanpura-Khanpur grabens in the southern part. Maximum sediment accumulation of more than 300 m is located in the southwestern part of the Luni basin, more specifically in the Ratanpura-Khanpur graben. Minor depressions also occur towards west of Jodhpur and east of Bhadrajun. Sediment filling in these graben depressions commenced with thick clay deposits followed by multistoried fining up sand and gravel sequences. Sediment accumulation centres are coincident with major tectonic lineaments and thus indicate that important loci of sediment accumulation are, possibly, a response to synsedimentary tectonics.