http://localhost:8081/jspui/handle/123456789/6 2026-10-05T07:27:38Z http://localhost:8081/jspui/handle/123456789/21745 Title: RARE Au-Cu OCCURRENCES IN THE METASEDIMENTARY ROCKS OF THE INNER LESSER HIMALAYAS Authors: Misra, Yash Vardhan Abstract: Himalayas are the ideal terranes for the precipitation of ore minerals as the belt is marked with complex tectonic and magmatic events which involve collision, subduction, break-up, detachment, accompanied by the obduction of the Eastern Gondwana continent and all these processes develop the optimum conditions for the precipitation of ore mineral deposits. Orogenic gold deposits are reported from the regionally metamorphosed terranes of all ages including Archean greenstone belts and younger phanerozoic metamorphic belts. In Himalayan region, gold, gold-antimony and antimony mineral deposits are reported from the Tethyan Himalayan belt in the Tibetan plateau. There are very few incidences of gold mineralization associated with the Lesser Himalayan metasediments. This study involves investigating the reported gold occurrences in association with sulphide mineralization within the quartz veins in the Deoban Dolostones and in the Mandhali carbonaceous shales and an attempt is made to underline the genesis of the gold occurrences within these rock types. SEM analysis for the polished sections has confirmed the presence of gold in the fracture spaces within the pyrites in the carbonaceous shales and within the chalcopyrite grains in the polished section of dolerite. EPMA studies have revealed the presence of native gold within the dolerite. It is suggested here from the petrographic studies of polished sections and SEM and EPMA studies that the gold precipitated from the ocean in the diagenetic pyrites after the deposition of the carbonaceous shales, and during the prograde metamorphism of the shales it got expelled from the crystal structure of the diagenetic pyrites and then the hydrothermal fluids exsolved from the dolerite intrusion in the later stages, after the deformation, reprecipitated the gold within the fracture spaces of the pyrites along with the coeval precipitation of chalcopyrite and sphalerite. In this case, carbonaceous shales are both the source as well as host rock for the gold deposits. The presence of gold prospects in the dolerite are attributed to be assimilated from the country rocks during its advancement towards the surface, and hence source rock for the gold in the dolerites could not be typified. 2022-04-01T00:00:00Z http://localhost:8081/jspui/handle/123456789/21744 Title: Determination of Groundwater Storage Variation, Deficit and Abstraction using GRACE Data in Afghanistan and the Evolution of Vadose Zone in Kabul City using Sentinel-1 Data Authors: Daqiq, Mohammad Taqi Abstract: Groundwater is the main water supply resource in Afghanistan. The country is facing a mismanagement surface water system. To make the groundwater crisis visible, the monthly groundwater storage variation (△GWS) has been calculated in (mm) with a trend value in (mm/month) in the time interval April 2002 to October 2021 by using the GRACE dataset for five major river basins of Afghanistan. The seasonal groundwater storage anomaly reveals a comparatively high negative trend in the Amu-Darya basin (-0.56 mm/month) and a low trend for the Northern basin (-0.13 mm/month). For Helmand, Hari Rud, and Kabul basins the trends are -0.50 mm/month, -0.42 mm/month, and -0.26 mm/month, respectively. The Standardized Precipitation Index (SPI) from the CHIRPS dataset is compared with seasonal △GWS over the five river basins. The comparison revealed a maximum negative SPI value (-1 to -2) in 2004, 2008, 2018, and 2021 indicating extremely to severe drought all over the basins, however, a normal to wet period was experienced from 2013 to 2017. A maximum and a minimum deseasonalized △GWS occurred for Amu-Darya (246 mm to -253 mm) and Hari Rud (89 mm to -102 mm), respectively. The long-term △GWS trend in flux (mm/year) and trend in mass (km3/year) has been calculated for all basins; Kabul (-2.464 mm/year & -0.172 km3/year), Amu-Darya (-4.799 mm/year & -0.426 km3/year), Northern (-0.682 mm/year & 0.053 km3/year), Hari Rud (-4.347 mm/year & -0.432 km3/year) and Helmand (-5.422 mm/year & -1.583 km3/year). The Groundwater Storage Deficit (GWSD) and GWSD Index (GWSDI) calculated, and a negative GWSDI value signified the groundwater drought. The highest negative GWSDI is determined for Kabul and Amu-Darya basins after 2018, whereas the rest of the basins is experiencing drought from 2011 to 2021 consistently. The Groundwater Storage Abstraction (GWSabs) has been analyzed for the whole of Afghanistan region. The estimated GWSabs trend in flux (2003-2021) geving a maximum value of 12.60 mm/year in the Northeast and Southwest parts of the country. The GWSabs trend in mass (2003-2021) calculated from the trend in flux with a maximum value (0.008 km3/year). A Spatio-temporal analysis was done which showed the maximum GWSabs variation up to 20.28 mm during 2005 and again in 2021. The land deformation in Kabul City (2015-2020) has been determined using Sentinel-1 data, and the time-series analysis shows two-phase of deformation. In phase I (2015-2017) there is a low negative trend (-20.66 mm/year in UKBL and -18.54 mm/year in LKBL), but in Phase II (2018-2020) there is showing a high negative trend (-151.34 mm/year in UKBL and -145.32 mm/year in LKBL). The maximum deformation of -395 mm showed up in 2020 for the Upper Kabul. 2022-05-01T00:00:00Z http://localhost:8081/jspui/handle/123456789/21556 Title: FORMATION EVALUATION OF ORGANIC RICH SOURCE ROCKS Authors: Dubey, Vaibhav Abstract: Due to the rapid depletion of conventional reservoirs around the world, unconventional resources that are present in abundance all around the world have gained increased attention form small and big exploration and production companies. These organic rich resources are quite complex in terms of its composition and exploitation. In order to calculate the possibility of a deep buried organic-rich source rock in terms of hydrocarbon saturation, concerted efforts are devoted at unravelling the resource potential of these unconventional formations. X-ray Diffraction (XRD), GRI Dean Stark extraction data, and LECO test are some of the measurements that provide ground truth value meant to calibrate the well logs measurements before an effective evaluation of the formation can be performed The workflow for these unconventional resources advocates the concentration of organic content in the grain matrix to be included when computing porosity. The Sondergeld (2010) porosity model is employed in Petrophysical modelling. To upgrade grain density, which is a needed input parameter to produce continuous porosity trend with depth, an empirical relationship between volume percentages of minerals and grain density (without kerogen) has been constructed. The Simandoux model (1963), which employed the volume of shale (Vsh), adjusted for overestimated saturation calculated using Archie's (1942) law, had the best correlation with GRI observed saturation. The petrophysical parameters predicted using logs, such as porosity and saturation, were found to have good correlation with laboratory observations, indicating the model's robustness. 2022-05-01T00:00:00Z http://localhost:8081/jspui/handle/123456789/21555 Title: Mg/Ca-derived sea surface temperature records from the Indian Ocean Authors: Kumar, Ujjawal Abstract: The Indian monsoon is important for more than one third population of the world. Understanding its past behavior is critical for forecasting its future behavior. To understand the changes in monsoon system of Indian subcontinent for the past 20 ka, Mg/Ca-based sea surface temperature records of different marine sediment cores from the Indian Ocean including the Arabian sea and Bay of Bengal is reviewed. From 17 Ka to 15 Ka (Heinrich Event), SSTs were warmer in general. During 14.7 Ka to 12.8 Ka (Bolling-Allerod), lower SSTs were observed, and Indian monsoon was stronger. While from 12.8 Ka to 11.5 Ka (Younger Dryas), there is an observed rise in sea surface temperature inferring that the Indian monsoon was weaker again. During the Holocene, the SSTs were inconsistently variable in general while the Indian monsoon was altogether stronger than the Deglaciation period. SST time series spectral analysis was also carried out to understand the periodicities and possible forcing factors of the monsoon. The observed periodicities mostly matched with solar insolation cycles and thermohaline circulation, which were also documented in previous studies, inferring that there is a tight relationship between the solar insolation, North Atlantic deep water system and associated ITCZ shifts, and the varying strengths of Indian monsoon during different time periods at various timescales. 2022-05-01T00:00:00Z