Aditya K. Verma

Bio: Aditya K. Verma is an academic researcher from Indian Institute of Technology Roorkee. The author has contributed to research in topics: Fault (geology) & Fluvial. The author has an hindex of 4, co-authored 6 publications receiving 43 citations.

Holocene tectono-geomorphic evolution of Haryana plains, Western Ganga plain, India

Abstract: Haryana plain is the drainage divide between the Ganga plain in the east and the Indus plain in the west. Being a part of the Himalayan foreland, its geomorphology, sedimentation processes, and tectonism are broadly controlled by the Himalayan tectonics. Soil and geomorphological mapping in Haryana plain bring out geomorphic features such as paleochannels, various active drainage patterns, and landforms such as old fluvial plains, floodplains, piedmonts, pediments, terminal fans, and eolian plains. Based on the degree of soil development, and Optical stimulated luminescence (OSL) ages, the soil-geomorphic units were grouped into six members (QIMS-I to VI) (Quaternary Indus Morphostratigraphic Sequence) of a morphostratigraphic sequence: QIMS-VI 9.86–5.38 Ka, QIMS-V 5.38–4.45 Ka, QIMS-IV 4.45–3.60 Ka, QIMS-III 3.60–2.91 Ka, QIMS-II < 2.91–1.52 Ka, and QIMS-I < 1.52 Ka. OSL chronology of different geomorphic features suggests six episodes of tectono-geomorphic evolution in the region since 10 Ka. Neotectonic features such as nine faults, two lineaments, and five fault-bounded tectonic blocks have been identified. Independent tilting and sagging of the blocks in response to neotectonics have resulted in modification of landforms, depositional processes, and hydro-geomorphology of the region. Major rivers like the Yamuna, the Ghaggar, and the Sutlej show different episodes of shifting of their courses. Lineament controlled few extinct channels have been recorded between 20 and 25 m depth below the surface in the ground-penetrating radar (GPR) profiles. These buried channels are aligned along the paleo-course of the Lost Saraswati River interpreted from the existing literature and hence are considered as the course of the lost river. Seven terminal fans have been formed on the downthrown blocks of the associated faults. The Markanda Terminal Fan, the first of such features described, is indeed a splay terminal fan and was formed by a splay distributary system of the Markanda River. Association of three terminal fans of different ages with the Karnal fault indicates the segment-wise development of the fault from west to east. Also, comparison with other such studies in the Ganga plain to further east suggests that the terminal fans formed by streams with distributary drainage pattern occur only in semiarid regions as in the present area and thus are indicators of semiarid climate/paleoclimate. Though the whole region is tectonically active, the region between the Rohtak fault and Hisar fault is most active at present signified by the concentration of earthquake epicenters.

Seismicity around the Mahendragarh–Dehradun basement fault in the western Ganga plain, India: a neotectonic perspective

Abstract: The NE–SW trending Mahendragarh–Dehradun Fault (MDF) is a basement fault in the western Ganga plain. The earthquake (4.7 mb) epicentered on this fault on 2nd June 2017 was focused around 10 km depth and does not show any surface rupture. Ground Penetrating Radar (GPR) survey around the epicenter detects few shallow-depth subsurface normal faults parallel to the MDF. However, it is unclear whether these normal faults are linked with the 2017 earthquake or other previous earthquakes. Seismic record (USGS) since 1975 to 2017 suggests occurrence of 22 earthquakes (~ 5 mb) around the MDF and majority (~ 63%) of these are clustered around Delhi and Rohtak. Following the 2017 earthquake, frequency of earthquakes occurence sharply increased than previously recorded instrumentation period from 1975 to 1995. Majority of the seismicity is focused around 10 km depths, shallowing to depths of 25–207 km recorded from 1975 to 2004. Earthquakes clustered along the Main Himalayan Thrust (MHT) shows similar temporal trend as near the MDF. Southward thrust movement of the Himalaya orogenic wedge predicts to impose strike-slip motion on the orthogonal-oriented steep basement faults, which is consistent with geologic and geomorphic field relations, and seismicity focal mechanisms along the MDF. The observed upper crustal deformation associated with such fault deformation pattern may be partly influenced by the MDF and partly by the foreland bulge seismicity. Potential tectono-geomorphic parameters and soil-chronosequence may suggest the surface deformation is active through the Holocene.

Paleoweathering and Paleoclimatic Reconstructions using Neoproterozoic Paleosol in the Eastern Margin of the Pranhita-Godavari Basin, India

Abstract: A thin, weakly-developed palaeosol horizon within the Neoproterozoic Sullavai sandstone in the eastern margin of the Pranhita-Godavari basin was studied. Field observations, thinsection studies and geochemical analyses of the palaeosol horizon were carried out to reconstruct the palaeo-weathering and palaeoclimatic conditions. The palaeosol developed on sandstone parent rock. Morphological features of this palaeosol are not distinct, perhaps due to very ancient nature as well as thin occurrence. A few of which that can be mentioned include weakly developed peds and calcareous nodules of size <1 cm -.2 cm. The lower part of the profile preserves incipient parent rocklamination. Major micromorphological features of this palaeosol include weakly-developed sub-angular blocky structure and redoximorphic features showing redox enrichment and redox depletion of Fe oxides and oxyhydroxides. XRD analysis of the palaeosol reveals the presence of glauconite and illite, suggesting deposition of sediments under shallow marine conditions, and prevalence of cold climate, respectively. This is also supported from Chemical Index of Alteration (CIA)and presence of illite. Further, Chemical Index of Weathering (CIW), Clayeness, and Salinization data of the palaeosol clearly suggests an environment where chemical weathering was feeble and cold (11-14°C) palaeo-temperature. XRF results show abundance of K, Ca and Mg which suggest the area was poorly drained along with cooler palaeoclimate during the late Neoproterozoic. Al2O3 concentration at the middle of the soil profile suggests weakly-developed B-horizon, however it is hardly observed in the field. Parent material, cold climate and less time of exposure only resulted in the formation of a thin and weaklydeveloped soil profile. This ancient soil may represent an unconformity at the basin boundary suggesting a local regression and exposure of the fluvio-marine deposits along the basin boundary. It further needs detailed such studies at various spatiotemporal basinal scales.

Influence of inherited Indian basement faults on the evolution of the Himalayan Orogen

Abstract: Abstract Indian basement faults, which bound three orogen-perpendicular palaeotopographic ridges of Precambrian Indian basement south of the Himalaya, extend to the base of the Indian lithosphere and to the northern extent of the Indian lithosphere underneath Tibet. In the eastern Himalaya, the active orogen-perpendicular Yadong–Gulu graben is aligned with an earthquake-generating strike-slip fault in the high Himalaya. We argue that the graben results from crustal necking during reactivation of the underplated basement fault. In the central Himalaya, along-strike diachronous deformation and metamorphism within the Himalayan metamorphic core, as well as lateral ramps in the foreland thrust belt, spatially correspond to the Lucknow and Pokhara lineaments that bound the subsurface Faizabad Ridge in the Indian basement. Analogue centrifuge modelling confirms that offset along such deep-seated basement faults can affect the location, orientation and type of structures developed at various stages of orogenesis and suggests that it is mechanically feasible for strain to propagate through a melt-weakened mid-crust. We suggest that inherited Indian basement faults affect the ramp-flat geometry of the basal Main Himalayan Thrust, partition the Himalayan range into distinct zones, localize east–west extension resulting in the Tibetan graben and, ultimately, contribute to lateral variability in tectonic evolution along the orogen's strike.

Effects of Killari earthquake on the paleo-channel of Tirna River Basin from Central India using anisotropy of magnetic susceptibility.

Abstract: The Killari Earthquake (Moment magnitude 6.1) of September 30, 1993, occurred in the state of Maharashtra, India, has an epicenter (18°03' N, 76°33' E) located at ~ 40 km SSW of Killari Town. The ~ 125 km long basin of Tirna River, close to the Killari Town, currently occupies the area that has witnessed episodic intra-cratonic earthquakes, including the Killari Earthquake, during last 800 years. The anisotropy of magnetic susceptibility (AMS) study was performed on ~ 233 soft sedimentary core samples from six successions located in the upper to lower stream of the Tirna River basin in the present study in order to evaluate the effects of earthquake on the river flow dynamics and its future consequence. The AMS Kmax orientations of the samples from the upper reach of the river section suggest that the sedimentation in this part of the river was controlled by a N-S to NNW-SSE fluvial regime with a low or medium flow velocity. In the middle reaches of the basin, an abrupt shift in the palaeo-flow direction occurred to W-E with low velocity flow. However, a NW-SE higher palaeo-flow regime is identified in the following central part of the basin in down-stream direction, followed by a low-velocity palaeo-flow regime at the lower reach of the Tirna basin. We attribute the sudden high flow velocity regime in the central part of the river basin to an enhanced gradient of the river that resulted from the reactivation of a NW-SE fault transecting the Tirna River basin at the Killari Town. As the NW-SE faulting in regional scale is attributed as the main cause of Killari Earthquake, the reactivation of this fault, thus, could enhance the further possibility of an earthquake in near future, and hence leading to devastating flood in the almost flat-lying downstream part of the Tirna River.