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    ABSTRACT: The Mahi and Kothiyakhad are two recently established marine formations from the Late Quaternary continental succession of the lower Mahi valley, Gujarat. These formations have yielded fairly rich assemblages of foraminiferids, confirming their marine origin. The Mahi Formation indicates that the first major transgression of about 7-8 m high took place around 240 Ka in the Mahi valley during Late Quaternary. However, the second transgressive phase at ∼ 4,000 years BP, represented by the Kothiyakhad Formation, is to be viewed in the light of the tectonic uplift in recent times. Results of radiocarbon dating of bottom and top mud layers of Kothiyakhad section indicate that the sea-level was high up to 2,000 years BP.
    Full-text · Dataset · Jul 2015
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    ABSTRACT: Morphotectonic analysis of landscape using remote sensing and GIS is an effective way of deducing the pattern and spatial variation of neotectonic activity along poorly investigated active faults. In this paper, we evaluate the neotectonic activity along a part of the seismically active but poorly understood Narmada–Son Fault (NSF), a more than 1000 km long ENE–WSW trending fault transecting through the central part of the Indian plate. The NSF in the study area is geomorphologically expressed as an ENE–WSW trending line of north facing scarps that delimit the rugged mountainous topography of the uplands to the south and the alluvial basin to the north which prominently slope away from the scarps. The scarps are developed in the south dipping basaltic flows belonging to the Deccan Trap Formation of the late Cretaceous–Eocene and continue westward into Tertiary rocks and further as a paleobank of the Narmada River. Field studies have revealed that the NSF in the study area is divisible into four morphotectonic segments (I to IV), which is attributed to the Tilakwada, Karjan, Madhumati and Rajpardi Faults cutting across the NSF. We characterize the neotectonic activity of the segments through DEM analysis, using geomorphic indices which include the mountain front sinuosity, hypsometric curves, hypsometric integral, asymmetry factor, stream length–gradient index and channel sinuosity. Interpretations of morphometric data are well supported by field data. Both the entire length of the NSF and the cross faults are found to be neotectonically active. We demonstrate that segment II has undergone the highest intensity of neotectonic activity followed by segments III, I and IV. This is corroborated by the highest elevation of scarps and the alluvial deposits, the deepest incision (~ 40 m depth) and steep northward slope of the alluvial plain in segment II. We infer that the NSF is characterized by differential uplift in recent past which agrees with the high angle reverse faulting with oblique-slip movements along the cross faults.
    No preview · Article · Jan 2013 · Geomorphology
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    ABSTRACT: The rivers of western India are monsoon dominated and have been so throughout the late Quaternary. Sediment accumulation in these river basins has been controlled by climatic and tectonic changes over a time span from the Late Pleistocene to the recent. The lithofacies assemblages associated with the various sediment archives in the Narmada basin range from the boulders of the alluvial fans to overbank fines on the alluvial plains. Estimates, based on clast size, of stream power and competence, bed shear stress and discharge reveal that hydrological conditions during the Late Pleistocene (∼90ka) were comparable to the present day. The size of the transported clasts and the thickness of the accumulated sediment indicate the influence of basin subsidence rather than an increase in discharge. Discharge estimates based on sedimentary structures preserved in the alluvial-plain facies suggest that the channel had a persistent flow, with a low width–depth ratio and large meander wavelength. The hydrological changes during the Holocene are more pronounced where the early Holocene is marked by a high-intensity hydrological regime that induced erosion and incision of the earlier sediments. The mid-Holocene stream channel was less sinuous and had a higher width–depth ratio and a higher meander amplitude in comparison with the present-day channel. Palaeo-fluvial reconstructions based on the sediment archives in the alluvial reach of the river basin are important tools in understanding the long-term hydrological changes and the intricate fluvial architecture preserved in the Narmada River basin ensures scope for detailed studies to identify phases of weak and enhanced hydrological regimes.
    Full-text · Article · Jan 2010 · Proceedings of the Geologists Association
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