Analysis of Folding in the Proterozoic Sedimentary Sequence of Bagalkot Group Exposed around Yadwad, N Karnataka, India:

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RESEARCH ARTICLE

Analysis of Folding in the Proterozoic Sedimentary Sequence of Bagalkot Group Exposed around Yadwad, N Karnataka, India: a Study Based on Remote Sensing Techniques and Field Investigations Pradeep B. Jadhav 1 & Lalitkumar K. Kshirsagar 1

Received: 5 March 2015 / Accepted: 11 April 2016 # Indian Society of Remote Sensing 2016

Abstract The deformed sedimentary sequence exposed in the core of Precambrian Kaladgi Basin, North Karnataka India, has given rise to prominent regional basinal structures with intervening anticlines. Deformation ceases away from the core part. The basinal structures are recognised on satellite images, aerial photographs and toposheets because of resistant segmented ridges of quartzite. A closure view of Bhuvan images around Yadwad village, North Karnataka, the core portion of Kaladgi Basin also revealed presence of folded geometry in the older carbonates of Bagalkot Group seen along the margins of the regional folds. Though folding in the sequence exposed in the region around Yadwad and further west is described by many authors, no detailed analysis of structures is available in published literature. An attempt is made here to map, analyse and integrate the structures in carbonates of Yadwad region on different scales observed in the field to find out their possible origin. It is suggested that the structures are syntectonic in origin formed in the presence of circulating fluids in high pressure and low temperature during the post depositional phase the Bagalkot sequence in which gravity played an important role in the formation of regional structures. The sequence also has recorded low grade of metamorphism as seen from the thin section observations.

Keywords Precambrian . Kaladgi basin . Yadwad . Deformation structures . Syntectonic . Harmonic folds

* Pradeep B. Jadhav [email protected]

1

Maharashtra Institute of Technology, Pune 411038, India

Introduction The Precambrian sedimentary sequence exposed over an area of 8000 sq. km. in north Karnataka, known as Kaladgi Basin (Foote 1876), has shown deformational structures typical of upper structural level (cf Bles and Feuga 1986) particularly in the core portion of the basin where the younger part of Bagalkot Group (Jadhav 1987) is well exposed. The intensity of deformation ceases considerably towards the basin margin. The basin is devoid of any significant magmatic history excepting a few locally mappable intrusive bodies (Patil Pillai 2005). The sequence is divided into an older deformed Bagalkot Group and a younger subhorizontal Badami Group (Vishwanathiah 1968, Jayaprakash et al. 1987; Kale and Phansalkar 1991). Twelve mappable folds with consistent EW to WNW-ESE axial trace are shown by the deformed Bagalkot Group interpreted from satellite images and aerial photographs. Jadhav (1999) based on detailed macro-mesomicro analysis concluded that the structural grain in the Deformed Bagalkot Group is a classic example of basement cover relationship in India, in which activation of basement structures have co