Sedimentology and the facies architecture of the Ghaggar‐Hakra Formation, Barmer Basin, India: Implications for early Cretaceous deposition on the north‐western Indian Plate margin

Abstract

Fluvial strata of the Lower Cretaceous Ghaggar‐Hakra Formation are exposed in fault blocks on the central‐eastern margin of the Barmer Basin, Rajasthan. The sedimentology of these outcrops are described from 114 logs (thicknesses up to 100 m) and 53 two‐dimensional correlation panels. The formation comprises three distinct channel belt sandstone packages defined as the Darjaniyon‐ki Dhani, Sarnoo and Nosar sandstones separated by thick siltstone‐dominated floodplain successions. The sediments were deposited in a sub‐tropical, low sinuosity fluvial system that matures into a highly sinuous fluvial system. The Nosar Sandstone, the youngest of the three packages, exhibits a significant increase in energy and erosive power compared to those underlying it. This distinct change in fluvial style is interpreted as being rejuvenation due to an actively developing rift network forming accommodation space, rather than climatic controls acting on part of the depositional system. Consequently, the Ghaggar‐Hakra Formation at outcrop represents Lower Cretaceous syn‐rift deposition within the Barmer Basin with active localized fault movement from Nosar Sandstone times onward. These findings provide sedimentological evidence in support of pre‐Palaeogene northwest–southeast extension in the Barmer Basin. Moreover, they imply Cretaceous extension took place widely along the northern extremity of the West Indian Rift System consistent with plate tectonic models of the break‐up of Gondwana and evolution of the Indian Ocean. Outcrops of Lower Cretaceous strata are patchy across India and Pakistan. This study provides valuable material which, when combined with the available published data, facilitates a re‐evaluation of Lower Cretaceous palaeogeography for the north‐west Indian Plate. The reconstruction demonstrates a complex fluvial system, where the sediments are preserved sporadically as early syn‐rift strata. The findings imply a high preservation potential for early Cretaceous fluvial successions within rifted fault blocks near Saraswati and Aishwarya of the Barmer Basin beneath the Palaeogene fill that likely have significant potential for further hydrocarbon exploration.

Origin of Lower Cretaceous quartzose arenites in northern India and the Indus Basins of Pakistan—The result of provenance composition, weathering or diagenesis?

“…The outcrops representing the Ghaggar-Hakra Formation are located on the eastern margin of the Barmer Basin and were deposited on a fault-bound relay ramp, oriented northeast-southwest (Bladon et al, 2015). This palaeogeographical context constrains the palaeoflow to the southwest and west (Beaumont et al, 2019;Sisodia & Singh, 2000) and implies a sediment source for this location from the north or northeast. Reported palaeocurrent readings for Lower Cretaceous sandstones throughout the WIRS and LMIB are also to the west and southwest (Table 1), reflecting a regional north-westerly regional palaeo-slope (see also Chaudhuri et al, 2018).…”

“…Preserved soil profiles reach up to 40 m in thickness in sediments of the Darjaniyon-ki Dhani Floodplain (Figures 3-5) and are colour-mottled from purplish red through orange to pale greenish-blue, with the pale colours typically representing iron oxidation-reduction reactions associated with organic material. A pronounced pedogenic fabric associated with rootlets is present in the upper part of this profile, with concentric colour mottling around the rootlets, and local rhizolith concretions (Figure 5; Beaumont et al, 2019). Small calcite and siderite nodules are present in the upper part of the floodplain sediments, but the siderite is highly oxidized to a suite of iron oxides, most likely due to soil-forming redoximorphic (oxidation-reduction) reactions (Driese et al, 1995;Salama & Anand, 2017).…”

“…Strata of the Lower Cretaceous Ghaggar-Hakra Formation occur unconformably over the Malani Igneous Suite in the Barmer Basin. The Ghaggar-Hakra Formation represents an intra-continental fluvial deposit and comprises three distinct sandstone units, together with floodplain mudstones and associated stabilized palaeosols (Beaumont et al, 2019). The oldest sandstone unit, the Darjaniyon-ki Dhani Sandstone (Figures 3 and 4; Bladon et al, 2015), was deposited as transient gravel bars, isolated channels and ephemeral floodplain deposits representing a bed load-dominant, highly avulsive, low sinuosity, fluvial system.…”

“…The formation is dated to the Albian/Aptian age of the Lower Cretaceous by pollen (cf. Beaumont et al, 2019). taken each time a change in the grain size occurred vertically through the succession in accordance with the guidelines of Vine and Tourtelot (1970).…”

“…For comparison, we compile previously published detrital mineralogical data from Lower Cretaceous sandstones across the WIRS and LMIB. We review the provenance terrains of the Lower Cretaceous sandstones in the light of detailed palaeogeographical reconstructions as set out by Beaumont et al (2019) to constrain in detail the spatial and temporal patterns of sediment dispersal systems.…”