Browsing by Author "R.C. Patel"

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Apatite and zircon fission-track thermochronology constraining the interplay between tectonics, topography and exhumation, Arunachal Himalaya
(Springer, 2021) James Pebam; Vikas Adlakha; A.K. Jain; R.C. Patel; Nand Lal; S. Singh; Rajeev Kumar; Rahul Devrani
Thirty-eight new apatite and zircon fission-track ages from 26 bedrock samples vary from 2.0 ± 0.3 to 12.1 ± 1.2 Ma, and 3.3 ± 0.3 and 13.2 ± 0.7 Ma, respectively, along three transects of the Kurung, Subansiri, and Siyom Rivers, which flow across the major structures of the Arunachal Himalaya. These cooling ages reveal marked variations in millennial-scale (>105 yr) exhumation rates from 0.6 to 3.0 mm/yr. A distinct positive correlation is visible between local topographic relief, hill slopes, channel steepness, and exhumation rates. The cooling ages are younger in the northern antiformal domains and older within the synformal nappe along the mountain front. Thermal modelling and time–temperature paths suggest that zones of rapid exhumation are controlled by structural windows within the Lesser Himalaya that were developed between 8 and 6 Ma over blind Main Himalayan Thrust (MHT). This time of rapid rock uplift and major topographic change led to a two-fold increase in the exhumation rates in the northern antiformal domains than the southern front of Arunachal Himalaya. Variation in cooling ages does not correlate with the present-day precipitation pattern. Tectonics appears to be the leading factor in driving the exhumation rates and landscape evolution in the Arunachal Himalaya. © 2021, Indian Academy of Sciences.
Apatite Fission Track Thermochronology: fundamentals, technique and review study from the Garhwal-Kumaun region, NW-Himalaya
(Wadia Institute of Himalayan Geology, 2022) Paramjeet Singh; R.C. Patel; S.K. Chaudhary
The aim of this paper is to enhance the awareness of the Fission Track (FT) analysis among the geosciences communities by describing the basic fundamentals, technique, and its geological applications. FT thermochronology has been widely used to constrain the exhumation and thermal histories of mountain belts. It is an ideal tool for reconstructing the thermal histories of a sedimentary basin, which provides detailed information on the exhumation of rocks, below about 110 ±10°C for apatite, as typically found in the upper 3-4 km of the shallow crust. Apatite Fission Track (AFT) thermochronology is applied to study the provenance history of sedimentary basins, structural evolution, and long-term exhumation history of orogenic belts. Here, we have compiled the available AFT age data from the Garhwal-Kumaun region of the LHS, LHC, and HHC zones and made observations to understand the exhumation and tectonics evolution of this portion of the Himalaya. The plot of AFT ages versus the horizontal distance from the Main Boundary Thrust (MBT) to the South Tibetan Detachment System (STDS) mirrors the exhumation patterns as predicted in the out-of-sequence (O-O-S) model of the Mio-Pliocene evolution of the Himalayan orogen. © 2022, Wadia Institute of Himalayan Geology. All rights reserved.
Geomorphic mapping and analysis of neotectonic structures in the piedmont alluvial zone of Haryana state, NW-India: a remote-sensing and GPR based approach
(Taylor and Francis Ltd., 2023) Harsh Kumar; R.S. Chatterjee; R.C. Patel; Abhishek Rawat; Somalin Nath
The Himalayan Frontal Thrust (HFT) and the surrounding piedmont alluvial region represent a zone of active deformation in the Indo-Gangetic plains. We investigated the Piedmont zone between the Ghaggar and Yamuna River basins in Haryana, India, for geomorphic signatures of active tectonics using remotely sensed data and validated by Geophysical Ground Penetrating Radar (GPR) surveys. The possible locations and the types of active tectonic features such as sub-surface fault, ridges, lineaments and warps were identified based on the presence of geomorphic signatures such as drainage gradient anomalies, abrupt change in flow direction, river offset, compressed meanders, paleochannels and topographic breaks. We used various optical satellite imageries to detect and map the temporal changes in the flow pattern of rivers in the study area. GPR investigations were done at selected test sites to locate and verify the continuity of subsurface fault. The GPR profiles were taken in the North-South direction using the common midpoint technique with 40 and 100 MHz antennae. Low frequency bi-static GPR scanning confirmed a number of dipping reflectors due to fault planes and warp surfaces in the study area. It is concluded that the piedmont zone of Haryana is actively deforming and could become a future seismic hazard zone. © 2023 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.
Mio-Pliocene exhumation of the hinterland and sediments provenance of the Neogene strata from Kumaun Himalaya of northwest India: Insights from detrital fission-track thermochronology
(John Wiley and Sons Ltd, 2024) Paramjeet Singh; R.C. Patel
Fission-track (FT) thermochronological analysis of detrital apatite and zircon derived from the lower and middle Siwalik Group of the sub-Himalaya allows the reconstruction of the long-term exhumation history of the Higher Himalayan Crystalline (HHC) and Lesser Himalayan Sequence (LHS), and also the provenance of the Siwalik sediments. Here, we report 14 detrital apatite and zircon fission-track (AFT/ZFT) ages of lower and middle Siwalik subgroups of the Kumaun region, northwest Himalaya. Detrital FT ages suggest that all sandstone samples were never buried below the temperature range of 90° to 100°C and remained as unreset to retain a signal of source-area exhumation. A detrital AFT age from sandstone sample at close proximity to the Main Boundary Thrust (MBT) is 4.4 ± 0.5 Ma (Pliocene time) which is completely reset and younger than the depositional age, while the detrital ZFT ages of the same sample are unrest. The AFT age represents the time of reactivation of the MBT during which ZFT ages were not affected. This study revealed that the provenances of Siwalik sediments are located majorly in the MBT hinterland areas and the nearest sources are Amritpur granite, the outer Lesser Himalayan meta-sedimentary (LHMS) zone, Almora klippe, Ramgarh thrust sheet, and the overlying Tethyan Himalayan Sequence. These source areas can be attributed to the development of local drainage networks in the Ramganga-Kosi drainage basin during late Miocene to Pliocene (i.e., ~9 to 4 Ma). Based on detrital FT datasets, it has been envisaged that different tectonic activities in the MBT hinterland area between Miocene and Pliocene Periods cause the tectonic upliftment and exhumation of source areas and supply the sediment to the Siwalik foreland basin. © 2023 John Wiley & Sons Ltd.
Miocene development of the Main Boundary Thrust and Ramgarh Thrust, and exhumation of Lesser Himalayan rocks of the Kumaun-Garhwal region, NW-Himalaya (India): Insights from Fission Track Thermochronology
(Elsevier Ltd, 2022) Paramjeet Singh; R.C. Patel
Bounded between the northeast dipping Main Boundary Thrust (MBT) at the base and the Saleri Thrust (ST) at the top, the Amritpur granite in the Kumaun-Garhwal region, NW-Himalaya is emplaced over the Siwalik sediments. As it is devoid of microscopic/mesoscopic imprints of the Himalayan tectonics, there is a debate regarding its emplacement along the MBT. While some interpret it as a klippe, others describe it as an intrusive body. The new apatite (AFT) and the zircon (ZFT) fission-track thermochronological data from the Amritpur granite provide similar age ranges and trends from the MBT to the ST. AFT ages range between 11.3 ± 1.6 and 14.7 ± 1.0 Ma with a weighted mean of 13.4 ± 1.5 Ma and ZFT ages range between 12.4 ± 1.2 and 15.4 ± 1.7 Ma with a weighted mean of 13.9 ± 1.2 Ma. Such age ranges and trends could be explained by rapid upliftment and exhumation of the Amritpur granite as horse rooted from the basement along the MBT from a depth of ∼8–10 km during mid-Miocene (∼14 to 13 Ma). We interpret this age as the time of development of the MBT. The new ZFT ages from the Jaunsar Group of the outer Lesser Himalayan meta-sedimentary (LHMS) zone range between 49.4 ± 2.0 and 80.3 ± 4.1 Ma (with a weighted mean of 67.5 ± 4.01 Ma) while the AFT ages range between 1.7 ± 0.2 and 4.2 ± 1.0 Ma (with a weighted mean of 3.17 ± 0.6 Ma). The old ZFT ages indicate that the outer LHMS zone underwent low-grade pre-Himalayan metamorphism (∼250 °C) around ∼67–72 Ma and the ZFT age of outer LHMS was not reset during the Himalayan orogeny. Young AFT ages from the Jaunsar Group of the outer LHMS zone reflect accelerated exhumation, likely due to reactivation of the MBT and its associated faults, since Plio-Pleistocene time. The new ZFT ages from the Ramgarh Thrust (RT) sheet range between 23.2 ± 2.4 and 24.2 ± 2.7 Ma with a weighted mean of 23.7 ± 2.5 Ma. The mean ZFT age of the RT sheet is similar to the age range of the Main Central Thrust (MCT) movements. This indicates that the RT sheet has been thrusted along the RT during 24 Ma followed by the exhumation of the RT sheet. © 2021 Elsevier Ltd
Tectonics of the Western, Sikkim and Arunachal Himalaya
(Indian National Science Academy, 2020) A.K. Jain; V.C. Thakur; M. Joshi; P.K. Mukherjee; R.C. Patel; Kathakali Bhattacharyya; Saurabh Singhal; K.K. Agarwal; Rahul Dixit; Gargi Deshmukh; Man Mohan
During the period 2016-2020, the Indian scientists undertook extensive research in the Himalayan Orogen, which incorporated extensive field mapping, structural analysis, geochemistry, metamorphic and igneous petrology, stratigraphy and palaeontology, Ar/Ar and U-Pb geochronology, besides low-temperature thermochronology. These activities were almost spread throughout the belt from western sector through Garhwal-Kumaon, Sikkim, Bhutan and Arunachal Pradesh. In addition, research was also undertaken using magnetotelluric methods for large-scale tectonics, seismology, paleoseismology and other disciplines, which are covered in other contributions. National laboratories have now started generating high-resolution U-Pb dates, which have been providing impetus to model Himalayan tectonics, besides modelling its Paleoproterozoic and Neoproterozoic configuration. © 2020 Indian National Science Academy. All rights reserved.