Petrography of Middle Jurassic to Early Cretaceous sandstones in the Kutch Basin, western India: Implications on provenance and basin evolution

Emilia Le Pera,Angana Chaudhuri,Santanu Banerjee

doi:10.1186/s42501-018-0002-6

Emilia Le Pera, Angana Chaudhuri + Show 1 more

Open Access

https://doi.org/10.1186/s42501-018-0002-6

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Abstract

This paper investigates the provenance of Middle Jurassic to Early Cretaceous sediments in the Kutch Basin, western India, on the basis of mineralogical investigations of sandstones composition (Quartz–Feldspar–Lithic (QFL) fragment), Zircon–Tourmaline–Rutile (ZTR) index, and mineral chemistry of heavy detrital minerals of the framework. The study also examines the compositional variation of the sandstone in relation to the evolution of the Kutch Basin, which originated as a rift basin during the Late Triassic and evolved into a passive margin basin by the end Cretaceous. This study analyzes sandstone samples of Jhumara, Jhuran and Bhuj Formations of Middle Jurassic, Upper Jurassic and Lower Cretaceous, respectively, in the Kutch Mainland. Sandstones record a compositional evolution from arkosic to subarkosic as the feldspar content decreases from 68% in the Jhumara Formation to 27% in the Bhuj Formation with intermediate values in the Jhuran Formation. The QFL modal composition indicates basement uplifted and transitional continental settings at source. Heavy mineral content of these sandstones reveals the occurrence of zircon, tourmaline, rutile, garnet, apatite, monazite and opaque minerals. Sub-rounded to well-rounded zircon grains indicate a polycyclic origin. ZTR indices for samples in Jhumara, Jhuran and Bhuj Formations are 25%, 30% and 50% respectively. Chemistry of opaque minerals reveals the occurrence of detrital varieties such as ilmenite, rutile, hematite/magnetite and pyrite, in a decreasing order of abundances. Chemistry of ilmenites in the Jhumara Formation reveals its derivation from dual felsic igneous and metabasic source, while those in Jhuran and Bhuj Formations indicate a metabasic derivation. Chemistry of garnet reveals predominantly Fe-rich (almandine) variety of metabasic origin. X-ray microscopic study provides the percentage of heavy minerals ranging from 3% to 5.26%. QFL detrital modes reflect the evolution of the basin from an active rift to a passive margin basin during the Mesozoic. Integration of results from QFL modal composition of the sandstones, heavy mineral analysis and mineral chemistry, suggests sediment supply from both northern and eastern highlands during the Middle Jurassic. The uplift along the Kutch Mainland Fault in the Early Cretaceous results in curtailment of sediment input from north.

Highlights

The objective of this study is to understand the source of sediments deposited in the Kutch Basin and to infer the tectonic framework of the basin during deposition of these sediments, based on conventional petrographic analysis and heavy mineral composition
3 Materials and methods This study focuses on the entire set of the grain population, including both light and heavy minerals present in the framework sandstones of Jhumara, Jhuran and Bhuj Formations, collected from six locations viz. Zara, Nirona, Palara, Gangeshwar, Bhuj and Tapkeshwar (Fig. 1a)
5 Discussion The Mesozoic Kutch Basin with southwesterly palaeoslope was bounded by two prominent highs, the Nagar Parkar Uplift to the north and the Aravalli Highlands to the east (Fig. 1a)

Summary

Introduction

Composition of major and accessory heavy minerals in sandstones provide crucial information regarding the provenance of sedimentary basins (Armstrong-Altrin et al 2012, 2015, 2017; Arribas et al 2000; Caracciolo et al 2012; Critelli and Ingersoll 1994; Critelli and Le Pera 1994; Critelli et al 2003; Le Pera and Critelli 1997; Paikaray et al 2008; Saha et al 2010). Heavy mineral constituents in sandstones further refines the understanding of provenance (Andò and Garzanti 2014; Andò et al 2012; Hounslow and Morton 2004; Hubert 1962; Mange and Maurer 1992; Mange and Morton 2007; Morton and Chenery 2009; Morton and Hallsworth 1999; Zack et al 2004). Garnets with low Mg and variable Ca are derived from amphibolite facies metasedimentary rocks while high Mg and high Ca indicate high-grade mafic and ultramafic gneissic source rocks (Mange and Morton 2007). The use of X-ray microscopic technique enables rapid visualization and quantification of dense phases (Andrews et al 2010)

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