Electrical resistivity is the only property of physics which give information of subsurface moisture content in the formation, Hence geophysical electrical resistivity survey was carried out to investigate the nature of shallow subsurface formations and geological contact in the main Gadilam river basin of Cuddalore District in Tamil Nadu. Twenty-seven vertical electrical soundings (VES) were conducted by Schlumberger configuration in the basin. Data is interpreted by curve matching techniques using IPI2 WIN software, layer parameters like apparent resistivity (?a) and thickness (h) interpretation were exported to Geographic Information System (GIS). Interpretation distinguishes three major geoelectric layers like topsoil, sandy clay layer, clayey sand layer along the contact zone in the basin. Interpreted VES sounding curves are mostly four-layer cases of QH, H, HA and KH type. Investigation demarcates lithology of subsurface and hydrogeological set up by employing maximum possible electrode sounding to infer saline water and freshwater occurrence based on resistivity signals. Zone of groundwater potential map was prepared with the combination of resistivity (?= ?1+ ?2+ ?3+ ?4) and corresponding thickness (T= T1+T2+T3+T4). High resistivity value of >200 ? m and low resistivity value of <10 ? m show the occurrence of alkaline and saline water within the formation aquifers as a result of possible rock water interaction and saline water dissolution. Four-layer resistivity cases from the matched curve (namely KH, AH, QA, and KA type) show the resistivity distribution/variation. It separates the freshwater depth wish from 1 to 140 ? m in fluvial sediments. Flood basin, sandstone and clay layer with low resistivity value of 3.16 - 7.5 ? m indicates contact with saline and freshwater aquifer. The Iso – resistivity map delineates saline water and freshwater zones with in the fourth layer cases in the same locations to indicate the irrational way of abstracting groundwater, resulting in saltwater ingress.

The current study deals with the application of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) multispectral data to delineate bauxite deposits over Mainpat plateau, Surguja district, Chhattisgarh, India. Application of specific band combinations help to delineate bauxite in the (SWIR) region (2.16-2.33 μm) and visible near infrared (VNIR) band (0.4–1.0 μm) of multispectral ASTER data. Various image processing techniques like atmospheric correction, minimum noise fraction, pixel purity index, n-dimensional visualiser, and spectral angle mapper were applied to ASTER image to delineate bauxite rich zones. The pure pixels were differentiated from the mixed pixels using pixel purity index which were further subjected to n-dimensional visualiser to identify the target end-members. The presence of bauxite was confirmed by comparing the spectral signatures of end-members with in-built spectral plots of United States Geological Survey spectral libraries and categorized as bauxite and ferruginous bauxite. Finally, the end-members were categorised as bauxite and ferruginous bauxite and mapped using spectral angle mapper. The result obtained was further compared with the lithological map provided by Geological Survey of India for accuracy. Then XRF analysis was carried out for the collected samples to confirm the presence of bauxite and ferruginous bauxite. Geochemical analysis also categorized the samples as bauxite and ferruginous bauxite that added accuracy to the results obtained from remote sensing technique. This study might be considered as a time saving eco-friendly exploitation of natural resources and finally the potential of multispectral ASTER data for mapping mineral resources.

In this study, we present the main findings from microstructural and mineralogical studies and their implications for the genesis of bauxite/laterite in Mainpat plateau. Megascopic studies showed reddish laterite to off-white bauxite. Strong hydrolytic action formed small oolites and large pisolites with sizes of 1-2 cm in diameter. Pisolites and oolites were elliptical, circular, and as broken pieces. Matrix of gibbsite and hematite was found in petrographic observations. Morphological characteristics include pisolitic, oolitic, lamellar, and euhedral gibbsite. Microstructures discovered were spongy gibbsite, flower-like crystals, elongated gibbsite, and framework type. Crystals of gibbsite were found to be predominant with partially crystallized ilmenite and hematite as subordinate phases. Scattered bauxite crystals made free pores for passage of solutions enhancing leaching conditions. Al, Ti, Fe, Si, Cu and Zn were identified as significant components; out of which, Al and Ti have the highest concentration. The samples have high alumina constitutes of 61.45% and 65.40% with a low iron content of 6.66% and 5.61%. High Ti content of 19.38% and 17.55% might be due to strong hydrolytic action during the alteration of basalt to bauxite. Low Si content of 2.68% indicates strong leaching activity. XRF analysis showed that the samples have undergone strong lateritization. XRD examination of bauxite/laterite revealed a mixture of minerals like gibbsite, boehmite, goethite, hematite, and anatase. Enrichment in boehmite shows in situ weathering. The study aims to extract the genesis and depositional characterization of bauxite through its morphological, microstructural, and mineralogical properties.