Abstract In 2005, the Maghreb Petroleum Research Group (MPRG), University College London, initiated a major research programme focused on the relatively poorly understood Neoproterozoic petroleum systems of the world. A series of research projects were undertaken to understand the generation and entrapment of hydrocarbons in this unique geological time interval, which is dominated by several episodes of global glaciations and post-glacial transgressions, coupled with basin development and rifting on a more local scale ( Craig et al. 2009 ). The research started with a field-based study of the Neoproterozoic sequences in North Africa (Libya, Morocco and Mauritania) and northern India (Rajasthan and Jammu & Kashmir). A series of international conferences, with field excursions/workshops, were run in parallel with the research programmes. The first of these was held at the Geological Society of London in November 2006 and the proceedings were published in 2009 in Geological Society London, Special Publication 326, entitled, ‘Global Neoproterozoic Petroleum Systems: the emerging potential in North Africa’ ( Craig et al. 2009 ). The second international conference was held at the University of Jammu in 2008 with a focus on the Neoproterozoic petroleum systems of Asia, including India, Pakistan, Oman, China and Siberia ( Bhat et al. 2008 ) (Fig. 1 ). This current volume contains some of the papers presented at the Jammu conference, in addition to new research on the geology and hydrocarbon potential of the Neoproterozoic–Cambrian basins of Asia. A third and concluding conference and an associated third Geological Society Special Publication will

Abstract The Indian Proterozoic Super Basins were part of the Northern Rim of Gondwanaland prior to its break-up along six major radial fractures. The Proterozoic rocks of these basins are extensively exposed in the northern as well as the southern parts of the Indian Peninsula. Based on recently conducted geochemical and seismic surveys within these basins, followed by well drilling in the Son Valley, Ganga Valley, and the Bikaner–Nagaur basin, it is concluded that hydrocarbons have been generated within these basins and conditions conducive to hydrocarbon accumulation exist within them. The discovery of gas within Son Valley has indicated the existence of an active Mesoproterozoic petroleum system that is likely to have continued up to Infracambrian times. Based on the correlation of Indian Proterozoic Super Basins with their analogous Chinese and Australian basins, it appears that elements of a similar petroleum system exist within these basins, together with the possibility of an active Ordovician–Silurian petroleum system within the northernmost Ganga Valley Vindhyans, where sedimentation continued up to the lower Devonian. Modelling and empirical data show that the Chambal Valley, as well as the probably trap-concealed Vindhyans, underwent intense wrenching during Neoproterozoic times, accompanied by good entrapment conditions. Even the peninsular SW Cuddapah Superbasin also appears worth exploring as an element of the Meso–Neoproterozoic petroleum system.

Abstract The burgeoning oil and gas consumption in India in recent years has necessitated looking into the Proterozoic basins of India, which are sparsely explored and have a scanty knowledge base. The rationale for hydrocarbon exploration in Indian Proterozoic basins is derived from the fact that they have large basinal areas, wide geographical distribution, varied geotectonic setting and sedimentary fill. The favourable tectonic settings of these basins, pronounced biological activity, known hydrocarbon gas seepages, and subsurface commercially viable oil and gas shows in the Bikaner–Nagaur and Vindhyan basins and analogous basins throughout the world necessitate proactive exploration strategies in these basins. The basins of Bikaner–Nagaur, Vindhyan, Cuddapah and Chhatishgarh include thick Neoproterozoic/basal Lower Palaeozoic (Cambrian) successions, in addition to Palaeoproterozoic and Mesoproterozoic sequences. The Neoproterozic sediments in these basins incorporate thick successions of shale, limestone and sandstone. These successions have rich organic matter of high-quality cyanophycean (stromatolites, acritarchs and filamentous algae) affinity that is proven to be high-quality (type one) source material for hydrocarbon generation and also involved in later structurization. However, the Neoproterozoic sedimentary pack in the Bhima–Kaladgi basins is comparatively less thick, and appears to have less prospectivity. The available geological and source-rock data are reassessed for their hydrocarbon prospectivity in order to help in planning a strategy for exploration in these basins.

Abstract In the central and western part of India, the Neoproterozoic deposits are identified in the Vindhyan and Marwar Basins. The Vindhyan Basin consists of two sub-basins; one in the eastern part and the other in the western part. The basic problem with the Vindhyan Basin is the correlation of the eastern part with the western part, as the two areas show different stratigraphic successions and the outcrops in the eastern part are not traceable in the western part. In this paper, an attempt is made to suggest intrabasinal correlation within the Vindhyan Basin on the basis of stromatolites, carbon isotope data, microbial mats, fossils and lithology. The Marwar Supergroup is developed in the western Rajasthan and unconformably overlies the Malani Igneous Suite, which has previously been dated as 779–681 Ma. On the basis of the available fossil records, the Jodhpur Group has been assigned an Ediacaran age and the Precambrian–Cambrian boundary is suggested within the Bilara Group. As both the Maihar Sandstone of the eastern part of the Vindhyan Basin and the Jodhpur Sandstone of the Marwar Supergroup have been assigned an Ediacaran age, these have been correlated.

Abstract The Upper Bhander Sandstone is dominantly composed of quartzarenites. The basal and top portions are sandstones, with the middle section comprising thinly bedded shales with interlayer silt and sandstone units. The sandstone units are composed of several varieties of quartz, feldspar, micas, rock fragments and heavy minerals. The Upper Bhander Sandstone was deposited in a transgressive phase and later modified by tidal processes and wave- and storm-dominated processes in a tide-influenced Barrier Beach Complex of the shallow marine environment. This study reveals that, during mechanical compaction, a rearrangement of grains took place and point and long contacts were formed. The early silica cementation and shallow burial resulted in high primary porosity. This phase was followed by chemical compaction and the replacement of silica cement by iron cement (Fe-cement) under the deep burial phase of these sandstones. Dissolution of Fe-cement and feldspars resulted in secondary porosity development. Quartz overgrowths are better developed on coarse- to medium-sized grains than on fine-sized grains. These observations suggest a progressive compaction, which initiated at the sediment–water interface and continued till deep burial diagenesis in a rapidly subsiding basin. The existing optical porosity of the Upper Bhander Sandstone is 4% and the minus cement porosity is 18%.