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

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.

PETROGRAPHIC, PHYSICAL AND MECHANICAL PROPERTIES OF SANDSTONE OF MIRPUR DISTRICT AREA STATE OF AJ&K, PAKISTAN

“…Silica overgrowth on quartz is collective in many samples. By the polarizing microscopic resulting carbonate and zeolite cement have been recognized [10]. The grains are easily deformed at high temperature.…”

“…In many rock samples silica commonly overgrowth on quartz. Mainly are abraded [10]. Both forms of feldspar are exchanged by cement replacement of plagioclase feldspar by cement is additional extensive.…”

Potential utility of reflectance spectroscopy in understanding the paleoecology and depositional history of different fossils

“…So, the absence of the above features may provide information on their (planktic foraminifera) paleoecology. Furthermore, the biominerals might have been assimilated from weathered basaltic products in the macrofossil shells (bivalve-gastropods and cephalopod-brachiopods) and were influenced by their ecological preferences 42,45 . The spectral contrast between bivalves and gastropods (similarly between brachiopods and cephalopods) deposited in a similar diagenetic and depositional set-up may provide valuable insight on their paleoecology.…”

“…The brachiopod ( Kallirhynchia fornix ) and cephalopod ( Hecticoceras sp.) samples were collected from the Jumara Formation (Callovian age of the Jurassic) and sediments were deposited from a mixed metabasic and felsic source 45 . The Jumara Formation was developed during the rift-climax, much before the Deccan volcanism, in a marine transgressive phase marking the maximum flooding surface 46 , whereas, post-rift Fulra Limestone and Chhasra Formations were developed after the Deccan Volcanism during transgressive phases 46 .…”

Provenance of upper Permian-lowermost Triassic sandstones, Wutonggou low-order cycle, Bogda Mountains, NW China: implications on the unroofing history of the Eastern North Tianshan Suture

“…Provenance studies of sandstones are useful to reconstruct the eroded parts of adjacent orogens (e.g., Dickinson and Suczek 1979;Ingersoll and Suczek 1979;Dickinson 1985;Dorsey 1988;Garzanti et al 1996Garzanti et al , 2007Trop and Ridgway 1997;Ingersoll 2012;Chaudhuri et al 2018). However, detailed reconstruction of rocks in the ENTS during the late Permian-earliest Triassic cannot be achieved by previous petrographic studies due to out-of-date chronostratigraphy or limited samples (Carroll et al 1995;Shao et al 2001;Greene et al 2005;Guan 2011).…”