Petrology of Lamproites from the Nuapada Lamproite Field, Bastar Craton, India

摘要: This work presents the first mineralogical, geochemical and 40Ar/39Ar geochronological data on hypabyssal facies lamproites near Kalmidadar Darlimunda in Nuapada Lamproite Field of Bastar Craton. The lamproite is a diamondiferous intrusion with surface dimension ~320 m × 160 m, whereas dyke swarm comprising clusters several narrow (<5 wide) elongated bodies. Indicator mineral suite around marked by abundance Cr-spinel, rarity garnet absence Cr-diopside picroilmenite. Mineralogically, comprises phenocrysts olivine (pseudomorphed calcite talc) microphenocrysts phlogopite set groundmass chlorite calcite. Ti rich (5.4–7.4 wt % TiO2), relationship between its content octahedral site deficiency indicates two substitution mechanisms, viz. + ▭ ↔ 2 Mg 2Al 2Si. have undergone pervasive hydrothermal and/or deuteric alteration, which has resulted complete chloritisation extensive silicification rocks. Tiny grains rutile apatite are commonly scattered both lamproites. high contents compatible elements such as V, Cr Ni incompatible Ba, Zr, Nb Hf. They also show REE enrichment LREE relative to HREE. element distribution patterns Nb, Sr, P, Hf Zr anomalies REE. observed petrological characteristics consistent derivation magma from metasomatised subcontinental lithospheric mantle source. Whole-rock isotopic yields an age 1055 ± 10 Ma for