The Paleo-Mesoarchaean Gondpipri mafic-ultramafic intrusions, western Bastar Archaean craton, central India; insights from bulk-rock geochemistry and Sm-Nd and S isotope studies on the formation of Ni-Cu-PGE mineralization

• Published in: Economic geology and the bulletin of the Society of Economic Geologists Vol. 117; no. 8; pp. 1845 - 1866
• Main Authors: Dora, M. L, Meshram, Tushar, Baswani, Srinivas R, Malviya, Vivek P, Mahapatro, Satya Narayana, Dash, Jitendra K, Meshram, Rajkumar R, Verma, Sanjeet K, Wankhade, Sanjay H, Mohanty, Manoranjan, Pati, Pitamber, Randive, Kirtikumar
• Format: Journal Article
• Language: English
• Published: Economic Geology Publishing Company 01-12-2022
• Subjects: Archean; Asia; Bastar Craton; chemical composition; copper ores; Economic geology; emplacement; Gondpipri Intrusion; igneous and metamorphic rocks; igneous rocks; India; Indian Peninsula; intrusions; isotope ratios; isotopes; layered intrusions; mafic composition; magmas; magmatism; Mesoarchean; metal ores; metals; mineral composition; mineral deposits, genesis; mineral exploration; mineralization; nickel ores; oxides; Paleoarchean; Petrology; platinum group; plutonic rocks; polymetallic ores; Precambrian; rare earths; S-34/S-32; Sm/Nd; stable isotopes; sulfur; ultramafics; whole rock
• ISSN: 0361-0128; 1554-0774
• DOI: 10.5382/econgeo.4947

Magmatic Ni-Cu-platinum group element (PGE)-Te mineralization in the Gondpipri mafic-ultramafic layered intrusion of ca. 3323 ± 74 Ma age, western Bastar craton, central India, is one of the most prospective exploration targets for magmatic sulfides in India. The Gondpipri layered intrusion is divided into two distinct group of rocks based on their mineralization potential, which includes (1) mineralized layered gabbro and pyroxenite and (2) a barren olivine gabbro intrusion. The host rocks show Cu + Ni concentrations up to 5,000 ppm with a Cu/Ni ratio <1 and all platinum group element (PGE) values between 0.1 and 1.1 ppm. Mineralization occurs in two modes: type I mineralization occurring as blebs, specks, and dissemination and type II mineralization occurring as stringers and minor veins. The geochemical data suggest that the parental magma of the host rock was generated at depths between spinel and garnet peridotite mantle source regions and subsequently modified by assimilation fractional crystallization (AFC) of the continental crust. High large ion lithophile elements, Th/Yb ratios of the studied rocks, and Sm-Nd isotope studies are consistent with a depleted mantle source. The geochemical proxies such as Th versus Ba/Th and (Ta/La)PM versus (Hf/Sm)PM and higher Sr/Nd (2.21-82.58) ratios indicate involvement of fluid-related subduction metasomatism and enrichment processes in an island-arc tectonic setting. Mineral assemblages and textural relationship between platinum group minerals (PGMs) and base metal sulfides suggest that sulfide-silicate liquid immiscibility was brought about by the precipitation of magnetite/Cr magnetite resulting in sulfide saturation in the melt by decreasing S solubility. Sulfur isotope compositions (δ34S: 1.61-3.30 ppm) and Sm-Nd geochemistry suggest that the sulfur was added in the tholeiitic magma by magmatic process. Crustal contamination played a significant role in sulfide saturation and in bringing about PGE and Te, As, Bi, Sb, Se (TABS) mineralization. PGM-NiTeBi developed at relatively low temperatures, where moncheite (PtPd)Te2 and merenskyite (PdTe) were formed at 650°C. The identification of Ni-Cu-PGM-Te in the margin of the western Bastar craton boosts deeper subsurface exploration.