Articles written in Journal of Earth System Science

    • Analyses of fold profiles by changing weight parameters of NURB curves

      Manash Pratim Gogoi Soumyajit Mukherjee Tapos K Goswami

      More Details Abstract Fulltext PDF

      Analyses of Non-Uniform Rational B-spline (NURB) curve by varying weights at its nodal points and projection ratio produce several kinetically plausible symmetric and asymmetric fold morphologies in 2D promptly and efficiently with varied overall geometries, curvature of limbs, sharpness/bluntness of hinges, extent of hinge zone, tightness/interlimb angles, etc. Some of these folds are new geometries what other approaches, such as those with Bézier curve, did not produce so far. Natural fold profiles can be matched with NURB curves from photographs.

    • Petrography and whole-rock geochemistry of Oligocene Barail Sandstones of Surma basin: Implications for tectono-provenance and paleoclimatic condition


      More Details Abstract Fulltext PDF

      The Oligocene Barail Sandstones of Surma basin from parts of Champhai District of Mizoram, northeast India has been studied for their tectono-provenance setting using petrography and geochemistry. The studied sandstones are poor to moderately sorted, subarkosic to sub-litharenite and show dominance of quartz (avg. 54.46%) followed by feldspars (avg. 7.22%), rock fragments (avg. 4.98%), mica (avg. 5.89%), matrix (avg. 14.47%) and cement (avg. 12.98%). Dominance of polycrystalline and undulatory monocrystalline quartz indicates contribution from medium grade metamorphic sources, primarily of granite gneisses. High concentration of SiO$_{2}$ with moderate to low concentration of Al$_{2}$O$_{3}$, Fe$_{2}$O$_{3}$, MgO, Na$_{2}$O and K$_{2}$O resembles the composition of upper continental crust. Moreover, moderate to high concentration of Th and V, depleted value of Ni along with TiO$_{2}$/Zr suggests derivation of sediments from felsic sources. The ratios of Eu/Eu* (avg. 0.63) and La$_{\rm {N}}$/Lu$_{\rm{N}}$ bears resemblance with the upper continental crust. Overall analyses show that the sediments were derived from the felsic terrain of neighbouring orogens probably represented by granite-gneisses and have undergone a moderate degree of weathering (avg. values of CIA: 70.20, CIW: 81.03, PIA: 77.63, WIP: 38.45, ICV: 1.06, I$_{\rm{w}}$ = 2) in a semi-humid to humid climatic conditions [Q$_{\rm{p}}$ /(F + RF):Q$_{\rm{t}}$ /(F + RF) = 0.20].

    • Tectonic instability of the petroliferous upper Assam valley (NE India): A geomorphic approach


      More Details Abstract Fulltext PDF

      Tectonic (in)stability of terrains is of major concern in financial investment for hydrocarbon exploration from such terrains. Morphometric studies of a river can explain neotectonics of the terrain. This study presents the southeast (SE) frontier of the Brahmaputra river valley of the upper part of the state of Assam, northeast India, where geomorphic changes are observed through remote sensing studies. Two primary geomorphic observations of the study are: (1) formation of palaeostream at the valley due to cut off of headwater discharge due to the activation of frontal thrust (Naga thrust) along the SE boundary of the valley and the Naga Hills (Assam–Arakan fold-thrust belt), and (2) shifting of confluence points Lohit river (tributary of the Brahmaputra river) causing avulsion and formation of a river island (Dibru Saikhowa). The first event is related to the recent tectonic activities, i.e., uplift of a fault-propagation fold (Digboi anticline). The later event of migration of the Lohit river might be associated with tilting of the SE side of the basin due to activities along the blind thrust systems of the Himalayan foot-hills and the basement high over the last 25 years. This gradually elongated its drainage basins. The southern propagation of the frontal thrust systems of Arunachal Himalaya and Mishmi hills has already shifted the course of the Lohit river towards the south leading to significant changes in geomorphology over the last few decades. N–S-oriented compressional stress axis apparently indicates possible movements along the fault systems bounding the inter-drainage basin facilitating the fluvio-morphometric changes.

    • Morphotectonic analysis of petroliferous Barmer rift basin (Rajasthan, India)


      More Details Abstract Fulltext PDF

      Geomorphologic studies can set important constraints on the petroleum geosciences of sedimentary basins. In the western Rajasthan area of Indian shield, constituting Barmer and other basins, rift-related sedimentation took place during Late Neoproterozoic to Cambrian Periods and during Mesozoic to Tertiary time. We analyze the Quaternary geomorphology of the Barmer basin mainly in terms of its watersheds by applying Digital Elevation Model aided by Beld verifications. In detail, we study aeolian landforms, drainage orientation, pattern, rejuvenation, terraces and abandoned gullies. Small streams display cross-valley anomalies. Gorge-like morphology in the eastern part of the basin near Sarnoo and knick-points in gullies near Lini/Sukri characterize the eastern boundary of the Barmer rift basin and parallel NE–SW river characterizes offset lineaments. Amongst the five delineated watersheds, watersheds- 1 and 2 are recognised as the most tectonically active having lower index of active tectonics (IAT). This is also supported by the linear-scale parameters stream length gradient index (SL), sinuosity index (SI) and the long-profiles. Sub-watershed analysis using SL and SI of the watershed-1 disclose the tectonically active region within the basin. Micro-scale basin analysis has also been made applying several quantitative indicators. Watersheds-1 and 2 were found to be tectonically active. Using the normalized difference vegetation index (NDVI), the NW–SE line of vegetation across the Giral coal mine in the northern part of the basin indicates a shallow groundwater level (${\sim}$7 mbgl), and can indicate presence of blind fractures.


      $\bullet$ Geomorphologic analysis of the Barmer basin.

      $\bullet$ Watersheds 1 and 2 are tectonically active.

      $\bullet$ Sub-surface brittle planes ascertained from watershed-1.

  • Journal of Earth System Science | News

    • Editorial Note on Continuous Article Publication

      Posted on July 25, 2019

      Click here for Editorial Note on CAP Mode

© 2021-2022 Indian Academy of Sciences, Bengaluru.