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Carbonatites are carbonate-rich rocks of igneous origin. They form the magmas of their own that are generated in the deep mantle by low degrees of partial melting of carbonated peridotite or eclogite source rocks. They are known to occur since the Archaean times till recent, the activity showing gradual increase from older to younger times. They are commonly associated with alkaline rocks and be genetically related with them. They often induce metasomatic alteration in the country rocks forming an aureole of fenitization around them. They are host for economically important mineral deposits including rare metals and REE. They are commonly associated with the continental rifts, but are also common in the orogenic belts; but not known to occur in the intra-plate regions. The carbonatites are known to occur all over the globe, majority of the occurrences located in Africa, Fenno-Scandinavia, Karelian-Kola, Mongolia, China, Australia, South America and India. In the Indian Subcontinent carbonatites occur in India, Pakistan, Afghanistan and Sri Lanka; but so far not known to occur in Nepal, Bhutan, Bangladesh and Myanmar. This paper takes an overview of the carbonatite occurrences in the Indian Subcontinent in the light of recent data. The localities being discussed in detail cover a considerable time range (>2400 Ma to

The Kondapalli Layered Complex (KLC) is a dismembered mafic-ultramafic layered intrusion, mainly composed of gabbroic and anorthositic rocks with subordinate ultramafics and chromitite. Chromitite occurs as lenses, pods, bands and disseminations. Platinum group of minerals (PGMs) occur as inclusions within chromite and silicates. The study indicates an inhomogeneous distribution of PGMs and distinct dominance of IPGEs over the PPGEs. The average ΣPGE content of chromite of KLC varies from 64 ppb to 576 ppb with Pt ranging from 5 to 495 ppb, Pd 5 to 191 ppb, Ir 3 to 106 ppb, Ru 3 to 376 ppb and Rh 3 to 135 ppb. The PGMs identified in the KLC indicate primary deposition of the IPGE, preceding chromite, indicating its orthomagmatic nature. Most of the PGM grains are usually below 10 μm. The identified PGMs are Laurite (RuS2), irarsite (Ir, As, S), iridosmine (Os, Ir), undetermined Os-Ir sulphide and Ru-Os-Ir-Zn alloys. Chromite also contains inclusions of pentlandite, millerite, chalcopyrite and pyrite. Study indicating that the KLC have orthomagmatic origin for PGE which are dominated by IPGE group and formed under surpa-subduction zone peridotite setting.

We present the findings on in situ trace element geochemistry of sulphides by LA‐ICPMS, sulphur isotope, and hydrothermal fluid evolution of copper ± gold mineralization at Dubarpeth, Central India. Mineralization is associated with chloritized‐silicified alteration zones, structurally localized along the terrain boundary fault between Archean TTG quartz diorite (2.5 Ga) of Western Bastar Craton and Paleo‐Mesoproterozoic cover sediments of Pranhita–Godavari (PG) Valley. Studies reveal that the Cu ± Au mineralization occurs in the form of dissemination, stringers, and veins along the microfaults and fractures. We infer three stages of mineralization based on the field observations and petrography studies. The early stage is characterized by the quartz–pyrite–chalcopyrite assemblage, while the middle stage is represented by quartz–chlorite–chalcopyrite ± pyrite. Calcite ± epidote is conspicuous in the late stage. Fluid inclusion microthermometry and Raman spectroscopy studies indicate that the early‐stage veins are mainly aqueous rich, mixed carbonic‐aqueous, and minor vapour‐rich aqueous inclusions. FIs in the early stage displayed evidence of vein formation during episode of fluid immiscibility with the homogenization temperatures and salinities up to 259°C and 27 wt.% NaCl equiv., respectively, indicating initial ore‐forming fluids of moderate temperature, moderate to high salinity in H2O–CO2–NaCl systems. Copper mineralization stage is liquid‐ and vapour‐rich (H2O–CO2–CH4 + N2) aqueous inclusions, with homogenization temperatures of 174–221°C and salinities of 6.37 to 13.9 wt.% NaCl equiv. This temperature range has been further supported by empirical chlorite thermometry based on Fe/Mg, AlIV, and AlV. The sulphur isotope values of pyrite and chalcopyrite showed δ34S interval of 2.29‰ to −10.85‰, characteristic of highly oxidized nature of the fluids and attributing sulphur source to magmatic origin. The ore‐forming fluids gradually became SO2−4 enriched and relatively oxidized during Cu mineralization. High Co–Ni trace element signatures of pyrite by LA‐ICPMS substantiate this observation, further indicating remobilization from a magmatic‐hydrothermal fluid. The presence of CH4 favours either a source of deep crustal nature or a mantle for the ore‐bearing fluid. We suggest that initial ore‐forming fluids are magmatic in origin that has been further cooled and diluted by mixing with meteoric water. Fluid boiling and mixing facilitated hydrothermal alteration and mineralization in the vicinity of the fault zone, which is perhaps activated during initiation of Paleo‐Mesoproterozoic segment of the Godavari Rift. The tectono‐magmatic setting, mineral assemblage, hydrothermal alteration, FIs, and trace element behaviour of pyrite (As–Co–Ni) suggest that the Dubarpeth Cu deposit is a high sulphidation epithermal vein type of deposit that is similar to those described for the shear/fault‐controlled epithermal deposits found elsewhere in the world. [ABSTRACT FROM AUTHOR]