Peperite Occurrence and its Implications on Origin and Temporal Development of the Proterozoic Dhala Basin, Mohar Area, Shivpuri District, Madhya Pradesh

Abstract

In the western part of Bundelkhand massif, a caldera with intra-caldera sediments, known as Dhala Formation, occurs as an outlier in and around Mohar village of Shivpuri district, Madhya Pradesh. For the first time, occurrence of peperite is being reported from the basal part of the Dhala sediment. Two types of peperites have been recognized: blocky and fluidal or globular with variable morphology. In peperitic zones, features like soft sediment deformations, presence of sediment into the rhyolite along cracks, vesiculation of the sediments and other evidences suggestive of sediment fluidization are some definite characteristics of interaction of hot magma with wet sediments forming peperite. The occurrence of peperites reflects the contemporaniety of deposition of the Dhala sediments and volcanism, which is well in accordance to the volcanic origin of Dhala structure. Further, the nature of unconformity between the Dhala and overlying Kaimur which is characterized by merely a few centimeter thick pebbly/conglomeratic bed does not appear to represent a large hiatus as expected between the Semri and Kaimur of Vindhyan Supergroup. So, the contemporaniety of the Dhala Formation (at least the lower part) as reflected by occurrence of peperites, coupled with the available age of the rhyolite and the nature of the unconformity between the Dhala and overlying Kaimur provide convincing evidence to correlate the Dhala Formation with the Lower part of the Kaimur and unlikely with the Semri Group or Bijawar as proposed earlier.

Pseudotachylitic breccia from the Dhala impact structure, north-central India: Texture, mineralogy and geochemical characterization

“…The suevite, in turn, overlies an impact melt rock sheet. Pati et al (2010) reported impact melt rock occurring as a continuous, sheet-like body over a 12 km 2 area extending NE-SW, with a thickness of up to 200 m. This was based on observations on more than 30 drill cores that reached core depths from sea-level down to 500 m. The suevite has only been intersected at the sub-surface and was termed earlier a "peperite" (Sinha et al, 2011). Except for drill core intersections, the contact between the basement rocks and the impact melt rock is only seen in exposure in the Maniar outcrop (N25°19'26.1"; E 78°9'37.9"), where it is sharp but undulatory.…”

Documentation of shock features in impactites from the Dhala impact structure, India

“…The presence of anomalously high iridium (Ir) contents in impact melt breccia (IMB), in comparison with the target rocks, and a very low osmium isotopic ratio indicated the presence of an extraterrestrial impactor component in impact melt breccia (Pati et al 2017). However, a number of studies have since continued to advocate an endogenous origin for this structure Sinha et al 2011;Markandeyulu et al 2014;Gaur et al 2016).…”

Peperites

“…The formation of peperites, which occurred by the interaction of lava with wet sediment, is a vitally significant environmental indicator. Nonetheless, few examples of this phenomenon have been comparatively documented, which happened during Archean successions (Beresford, et al, 2002;Wilson and Grant, 2006;Moulton, et al, 2011;Barnes and Van Kranendonk, 2014;Barnes and Arndt, 2019); Proterozoic succession (McPhie, 1993;Rawlings, 1993;Biske, Romashkin and Rychanchik, 2004;Sinha, et al, 2011;Constenius, et al, 2017); Palaeozoic succession (Brooks, 1995;Doyle, 2000;Cas, et al, 2001;Chen, et al, 2013;Zhu, et al, 2014;Chen, et al, 2016;Memtimin, et al, 2020;Bann, Jones and Graham, 2022); Mesozoic succession (Wilson, 1991;Wilson, 1993;Hanson and Hargrove, 1999;Templeton and Hanson, 2003;Hanson and, Nemeth, Breitkreutz and Wilke, et al, 2004;Palinkaš, et al, 2008;Asvesta and Dimitriadis, 2013;Krobicki, et al, 2019); Cenozoic succession (Erkül, Helvaci and Sözbilir, 2006;Martin and Németh, 2007;Busby, et al, 2008;Haller and Németh, 2009;Nouri, et al, 2017); and to the most recent Pleistocene succession around 43,000-12,400 years ago (Mercurio, 2011). However, it has also been pointed out by (Skilling, et al, 2002) that in ancient deposits, it may be difficult to differentiate fragments obtained from this process from those of tectonic origin.…”