Depositional sequences and sea level changes during Bathonian-Oxfordian, Kutch (Kachchh) Basin, Gujarat, India

Abstract

The Kutch sedimentary basin is situated at extreme west of Indian Peninsula is an excellent example of cyclic sedimentation in Mesozoic shallow marine regime. The Bathonian to Santonian shallow marine rocks crops out in the Kutch Mainland extending for ~ 193 km from Habo in the east to Lakhpat in the west. Based on detail field studies in the Jhura dome, Kutch Mainland and laboratory investigations of 43 carbonate rock samples, the 370 m succession of carbonate-dominated rocks is stacked into three depositional sequences of regional importance. The 84 m Transgressive sequence-I of Bathonian age consisting of four microfacies assemblages represents an upward deepening facies succession. The 130 m regressive sequence of Callovian age composed of five microfacies assemblages showing upward shoaling facies succession. It was deposited during stillstand period followed by gradual increase in sediment supply. The 155 m transgressive sequence II of Early Oxfordian age consists of four microfacies assemblages that deposited during highstand of sea level in the basin together with episodic and less sediment supply. The relative sea level curves indicate high-order sea level variation during whole sequence before to major drop in sea level at the end of the transgressive sequence-II. The microfacies study reveals that these high order sequences are regionally comparable and might have been controlled by an active tectonic mechanism together with global sea level change.