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

Abstract

This work presents the first mineralogical, geochemical and 40 Ar/ 39 Ar geochronological data on hypabyssal facies lamproites near Kalmidadar and Darlimunda in the Nuapada Lamproite Field of the Bastar Craton. The Kalmidadar lamproite is a diamondiferous intrusion with surface dimension of *320 m 9 160 m, whereas the Darlimunda lamproite is a dyke swarm comprising clusters of several narrow (\5 m wide) and elongated bodies. Indicator mineral suite around the Kalmidadar lamproite is marked by abundance of Cr-spinel, rarity of garnet and absence of Cr-diopside and picroilmenite. Mineralogically, the Kalmidadar lamproite comprises phenocrysts of olivine (pseudomorphed by calcite and talc) and microphenocrysts of phlogopite set in a groundmass of chlorite and calcite. The phlogopite is Ti rich (5.4-7.4 wt % TiO 2 ), and the relationship between its Ti content and octahedral site deficiency indicates two substitution mechanisms, viz. Ti + ' $ 2 Mg and Ti ? 2Al $ Mg ? 2Si. The Darlimunda lamproites have undergone pervasive hydrothermal and/or deuteric alteration, which has resulted in complete chloritisation of phlogopite and extensive silicification of the rocks. Tiny grains of rutile and apatite are commonly scattered in the groundmass of both Kalmidadar and Darlimunda lamproites. The Nuapada lamproites have high contents of compatible elements such as V, Cr and Ni and of incompatible elements such as Ba, Zr, Nb and Hf. They also show high abundance of REE and enrichment in LREE relative to HREE. The incompatible element distribution patterns of the lamproites are marked by Nb, Sr, P, Hf and Zr anomalies relative to REE. The observed petrological and geochemical characteristics of the Nuapada lamproites are consistent with the derivation of the magma from a metasomatised subcontinental lithospheric mantle source. Whole-rock 40 Ar/ 39 Ar isotopic data yields an age of 1055 ± 10 Ma for the Nuapada lamproites.

Proterozoic felsic and mafic magmatism in India: Implications for crustal evolution through crust-mantle interactions

“…Further there are no matching of dyke events between Dharwar and Bundelkhand cratons except those of 1.10-1.12 Ga. Bundelkhand craton experienced two major dyke events, 1.98 Ga and 1.11 Ga, for Jhansi and Mahoba swarms respectively Ernst, 2014;Samal et al, 2019). Mahoba swarm is comparable with 1.10-1.12 Ga kimberlites of Dharwar craton and 1.05 Ga lamproites of Bastar craton (Sahu et al, 2013;Rao et al, 2016). There is no match found for 1.98 Ga Jhansi dyke event in any of the Indian cratons.…”

Petrogenesis of Mesoproterozoic lamproite dykes from the Garledinne (Banganapalle) cluster, south-western Cuddapah Basin, southern India

“…As a result, most of the current lamproite petrogenetic models are strongly influenced by studies on Phanerozoic lamproites (e.g., Leucite Hills, Smoky Butte, West Kimberley, Gaussberg, and the Mediterranean region; Murphy et al 2002;Carlier and Lorand 2003;Coban and Flower 2006;Mirnejad and Bell 2006;Davies et al 2006;Prelević et al 2012). A significant number of Mesoproterozoic lamproites occur in the Eastern Dharwar, the Bastar and the Bundelkhand cratons of the Indian shield (Chalapathi Rao et al 1996Rao et al , 1999Kumar et al 2001;Osborne et al 2011;Sahu et al 2013) and they provide a unique opportunity to understand the tectonomagmatic processes when these cratons constituted a part of Proterozoic supercontinents such as Columbia and Rodinia. Furthermore, the spatial association of Mesoproterozoic lamproites, some of which are diamondiferous, with two of the major Proterozoic Purāna sedimentary basins of peninsular India -the Vindhyan (Chalapathi Rao 2005 and references therein; Masun et al 2009) in central India and the Cuddapah (Bergman 1987;Chalapathi Rao 2007) in southern Indiaremains one of the puzzling aspects of Indian geology.…”