Macrofacies Architecture of the First Transgressive Suite Along the Southern Margin of the Kaladgi Basin

Abstract

Abstract The lowest sequence of the Lokapur Subgroup from the Bagalkot Group manifests the earliest transgression in the Meso-Neoproterozoic Kaladgi Basin. It is characterised by four sedimentary lithofacies namely, (i) sandstone facies (dominantly quartzose-arenites with minor interbedded conglomerates and gravel beds), (ii) argillite facies (including siltstones and shales), (iii) carbonate facies (primarily dolomites which are often cherty and stromatolitic) and, (iv) chertbreccia facies (poorly bedded and silicified). These four macrofacies have been studied in the gently folded and faulted exposures along the southern margin of the Kaladgi Basin. An unfolded fence of their distribution and mutual dispositions is reconstructed so as to enable the visualization of their syndepositional architecture. Modifications of the existing classification of the examined sequence of the Lokapur Subgroup are suggested on the basis of this restoration and in context of process responsive lithostratigraphy. The Kaladgi Basin is interpreted to have been initiated in an extensional tectonic regime. All the four recognised macrofacies were deposited more or less simultaneously during the earliest transgression in this basin and their architecture was governed by synsedimentary events of sagging of the uneven basin floor along an array of East-West trending growth faults with northern downthrows.