[en] High resolution heliborne geophysical survey data with magnetic, time domain electromagnetic and gamma-ray spectrometric sensors over Alwar sub-basin of North Delhi Fold Belt from north of Jaipur to north of Alwar are interpreted. Metasediments of basin are predominantly non-magnetic manifesting low amplitude and low frequency magnetic signature except basic volcanics of Raialo, magnetite quartizite-phyllite of Alwar and Ajabgarh Groups and later intrusives that impart higher amplitude magnetic anomalies. NNE-SSW to N-S trending concealed fold axes and parallel shears and NW-SE to E-W lineaments/ faults related to younger structure have been identified. Exposed intrusive granite of Bairat, Barodia, Dadikar and Harsora with higher radioelement concentration and feldspathic quartzite of Alwar Group with higher concentration of potassium are very well discernable through radiometric data. Borewell water showing radioactivity above threshold at a few locations in the northeastern part of the basin indicate possible presence of radioelement concentration. Lenses and thick pile of carbonaceous phyllite of Raialo and Ajabgarh Groups are delineated from conductivity image of Time domain electromagnetic data. Airborne Inductive Induced Polarisation effect near Khoh, Agar-Bhaonta, Bansur, Sirawas and other places indicate presence of polarizable materials. Integrated study including geological interpretation of the datasets led to demarcation of target areas for further exploration for uranium mineralisation. (author)

[en] High resolution heliborne magnetic, time domain electromagnetic and gamma-ray spectrometric data acquired over a part of Paleo-Proterozoic Aravalli Fold Belt (AFB) have brought out the surface and subsurface geological attributes owing to physical property contrast. Complexly deformed meta-volcano-sedimentary sequence of Paleo-Proterozoic arcuate lower and middle sequence of Aravalli Supergroup unconformably overlying Archean basement of Bhilwara Supergroup extends from Nathdwara in the north to Banswara in south. Concealed extension of basic volcanics of Debari Group below the overlying metasediments is identified based on the longer wavelength, higher amplitude and trend of magnetic anomalies. The younger basic plugs/ dykes transecting the basinal sequence and faults varying from NW to NE trend have been picked up from magnetic signatures. The nature of radioelement distribution obtained from gamma-ray spectrometric data clearly differentiate the Archean basement and its inliers in Sarara-Mando ki Pal sector, basinal sediments of Debari Group, Udaipur Group and intrusive granites. Occurrence of another inlier at Metwala is revealed through radiometric signature. Conductive carbonaceous phyllite of Debari Group reflected in time domain electromagnetic data prominently reflects the folded structure in southeastern part near Parsola-Banswara tract thereby aiding to delineate axial trend and map the fold pattern. Conductive signature and subsequent ground validation revealed occurrence of carbonaceous partings in some parts of dolomite of Debari Group. Interpretation of heliborne geophysical data has enhanced geological knowledge of the Aravalli Supergroup. (author)