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Geomorphologic studies can set important constraints on the petroleum geosciences of sedimentary basins. In the western Rajasthan area of Indian shield, constituting Barmer and other basins, rift-related sedimentation took place during Late Neoproterozoic to Cambrian Periods and during Mesozoic to Tertiary time. We analyze the Quaternary geomorphology of the Barmer basin mainly in terms of its watersheds by applying Digital Elevation Model aided by field verifications. In detail, we study aeolian landforms, drainage orientation, pattern, rejuvenation, terraces and abandoned gullies. Small streams display cross-valley anomalies. Gorge-like morphology in the eastern part of the basin near Sarnoo and knick-points in gullies near Lini/Sukri characterize the eastern boundary of the Barmer rift basin and parallel NE–SW river characterizes offset lineaments. Amongst the five delineated watersheds, watersheds-1 and 2 are recognised as the most tectonically active having lower index of active tectonics (IAT). This is also supported by the linear-scale parameters stream length gradient index (SL), sinuosity index (SI) and the long-profiles. Sub-watershed analysis using SL and SI of the watershed-1 disclose the tectonically active region within the basin. Micro-scale basin analysis has also been made applying several quantitative indicators. Watersheds-1 and 2 were found to be tectonically active. Using the normalized difference vegetation index (NDVI), the NW–SE line of vegetation across the Giral coal mine in the northern part of the basin indicates a shallow groundwater level (~7 mbgl), and can indicate presence of blind fractures. Research Highlights: Geomorphologic analysis of the Barmer basin. Watersheds 1 and 2 are tectonically active. Sub-surface brittle planes ascertained from watershed-1. [ABSTRACT FROM AUTHOR]

Hydrocarbon exploration and production are going on in Barmer basin (Rajasthan, India) for more than a decade. The potential source rocks are of Paleocene – Eocene age, and Mesozoic siltstones form the reservoirs. The western and central portions of the Rajasthan basin are characterised by extensive lignite formations, which can be promising for artificial transformation to oil and gas. We study the source rock properties, depositional environments and hydrocarbon generation potential of the Paleogene lignitic shales of the Giral lignite mine and the Cretaceous Sarnu siltstones for their source and reservoir rock potentiality. The total organic carbon content (TOC) of the Giral samples range between 0.76 and 49.83 wt% and the thermal maturity, as reflected by the pyrolysis T max , lies between 412 and 468 °C. Sarnoo siltstones, on the other hand, have a very low TOC ranging from 0.02 to 0.08 wt% and a T max of 320–608 °C. The higher TOC and a lower oxygen index (OI) of Giral lignites and shaly lignites indicate the prevalence of a reducing depositional environment. Bulk organic geochemical parameters involving kerogen pyrolysis and thermal degradation kinetics indicate a more promising hydrocarbon generation potential in the lignite than shales, which, however exhibits higher thermal maturity of organic matter. Giral lignites as well as shales show dominantly Type-III heterogeneous kerogen, which is sourced from terrestrial organic matter. This is also corroborated by a broader distribution of activation energy derived from the thermal decomposition of the kerogen. The kerogen transformation ratio (KTR) and the hydrocarbon generation rate (HGR) suggest a considerably earlier and quicker kerogen transformation. Samples from the Sarnoo area offer no significant information on the source rock characteristics, due to their lean organic nature. However, lignites and shaly lignites of the Giral mine are identified as excellent candidates for their suitability towards easy conversion into hydrocarbon products through artificial techniques. • Hydrocarbon generation potential and source rock kinetics of Barmer basin studied. • Organic matter in shaly lignites characterised by high TOC and thermally mature Type III kerogen. • Kerogen decomposition kinetics suggests relatively earlier and faster temperature of transformation for shaly lignites. • Shaly lignites promising candidate for artificial maturation into oil and gas. [ABSTRACT FROM AUTHOR]