Climate and tectonic forcings driving the coastal landscape evolution: clues form late quaternary fan lobes in Kachchh region (NW India)

Abstract

<p>160 km long hill ranges in the Kachchh region (NW-India) form a major E-W oriented topographic break delimiting the marshy plain of Banni in the North from the more elevated area of the Katrol Hill Range (KHR) in the south. Such topographic break is considered as the superficial expression of a quaternary active fault labelled Kachchh Mainland Fault (KMF). Numerous rivers cross this hilly region flowing roughly from South to North. The majority of those rivers are characterized by extensive fan lobes pinching out from the 200–300-meter anticlines of the hilly range.</p><p>Starting from archaeological evidence from the past 4000-5000 years, it has been inferred that an extremely fast coastal landscape evolution brought such a region to evolve from an initial gulf landform to the current setting, i.e., the marshy plains of Banni and the salt-encrusted Rann. The location of the fans lobes marked the boundary between the fluvial and marine environments.</p><p>High sedimentation rates varying between 1.1-2 mm/yr reported for the Banni plains together with historical and recent earthquakes (1668 Indus Delta, 1819 Allah Bund, 1845 Lakhpat, 1956 Anjar and 2001 Bhuj) provide valuable constraints for inferring the climatic and tectonic forcing on the region's quick dynamics.</p><p>In our ongoing work, we propose a multidisciplinary approach made by morphotectonic mapping, morphometric analyses, and geochronology to understand better how the interplay of tectonics and eustatic perturbations drove such an abrupt landscape evolution.</p>