Geoscientists have extensively used machine learning for geological mapping and exploring the mineral prospect of a province. However, the interpretation of results becomes challenging due to the complexity of machine learning models. This study uses a convolutional neural network (CNN) and Shapley additive explanation (SHAP) to estimate potential locations for gold mineralisation in Rengali Province, a tectonised mosaic of volcano-sedimentary sequences juxtaposed at the interface of the Archaean cratonic segment in the north and the Proterozoic granulite provinces of the Eastern Ghats Belt in Eastern India. The objective is to integrate multi-thematic data involving geological, geophysical, mineralogical and geochemical surveys on a 1:50 K scale with the aim of prognosticating gold mineralisation. The available data utilised during the integration include aero-geophysical (aeromagnetic and aerospectrometric), geochemical (national geochemical mapping), ground geophysical (gravity), satellite gravity, remote sensing (multispectral) and National Geomorphology and Lineament Project structural lineament maps obtained from the Geological Survey of India Database. The CNN model has an overall accuracy of 90%. The SHAP values demonstrate that the major contributing factors are, in sequential order, antimony, clay, lead, arsenic content and a magnetic anomaly in CNN modelling. Geochemical pathfinders, including geophysical factors, have high importance, followed by the shear zones in mineralisation mapping. According to the results, the central parts of the study area, including the river valley, have higher gold prospects than the surrounding areas. Gold mineralisation is possibly associated with intermediate metavolcanics along the shear zone, which is later intruded by quartz veins in the northern part of the Rengali Province. This work intends to model known occurrences with respect to multiple themes so that the results can be replicated in surrounding areas.

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The western margin of the north Delhi fold belt, Rajasthan is mostly covered by the thick alluvium-sand cover of the Thar Desert. However, a study on a cluster of scattered and deformed serpentinite bodies exposed in the small opencast quarries are presented here. Though alteration and absence of primary phases possess constraints over petrogenesis, but, the accessory, anhedral spinel chemistry aids in the genetic reconstruction. The unaltered core part of the spinel that is, the Al-chromite (avg. 45.2 wt% Cr 2 O 3 ), followed by ferrit chromite (avg. 32.3 wt% Cr 2 O 3 ) inner rim and magnetite towards the outer rim is the character of spinels present in the host, where the chemistry of the core part is used exclusively. This core part of spinel preserves the primary mantle signature and attests the forearc peridotite character and a similar subduction-related trait is followed by the whole-rock major oxide proxies.Cumulative petrological, whole-rock geochemistry, and mineral chemical signature unequivocally advocate towards a harzburgitic protolith, an arc peridotitic character, and presence of ancient forearc environment. The present communication is the first to describe the detailed characterization of serpentinite bodies with a possible linkage towards the presence of ancient oceanic slices in the north Delhi fold belt, Rajasthan, NW India.

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Aladahalli-Nuggihalli Schist belt of Karnataka in Western Dharwar Craton is well known for its remobilized volcanic exhalative type base-metal mineralization. The schist belt comprises metamorphosed mafic-ultramafic rock assemblage, traversed by quartz veins. The study area belonging to the southern extension of the schist belt is chosen on the basis of bipolar aero-magnetic anomaly (magnetic high) and higher order EM channels (4th, 5th and 6th) along with favourable geological conditions for mineralization. Lithology of the area includes metabasics (dominant) and meta-ultramafics intricately associated with pegmatite dykes and quartz veins. Subsurface mineral exploration programmes carried out in Aladahalli belt shows a close link between the quartz veins and sulphide mineralisation. Fluid inclusion study has been carried out on quartz samples from these veins to characterise the composition and P – T condition of entrapment of fluid inclusions. Three contrasting types of fluid inclusions are reported suggesting moderate to low salinity hydrothermal fluid pertaining to shallow-level epithermal condition.