Major element composition of concentrate garnets in Proterozoic kimberlites from the Eastern Dharwar Craton, India: Implications on sub-continental lithospheric mantle

Patel, Suresh C.; Ravi, S.; Anilkumar, Y.; Pati, Jayanta Kumar

doi:10.1016/j.jseaes.2010.04.020

Cited by 9 publications

(6 citation statements)

References 33 publications

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“…These P-T conditions are consistent with a mantle geotherm of 45 mW/m 2 , following the model continental geotherms of Pollack and Chapman (1977). This is same as the mantle geotherm beneath the kimberlite fields of the Dharwar Craton reported by Patel et al (2009Patel et al ( ), 2010. Using the geotherm of 45 mW/m 2 , the minimum pressures obtained for the Kalmidadar garnets fall in the range of 16-32 kbar, which correspond to a minimum depth range of 50-100 km.…”

Section: Nature Of Subcontinental Lithospheric Mantlesupporting

confidence: 81%

“…The Ca-saturated composition of the Kalmidadar pyropes indicates that the pyropes have equilibrated with clinopyroxene in a lherzolitic mantle. Similar mantle lithology is indicated beneath the kimberlites of the Dharwar and Bastar cratons (Patel et al 2010;Mainkar 2011, Sum (X site) respectively) from the composition of pyropes in the respective indicator mineral suites.…”

Section: Nature Of Subcontinental Lithospheric Mantlesupporting

confidence: 55%

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

Sahu

Gupta²,

Patel³

et al. 2013

Proceedings of 10th International Kimberlite Conference

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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.

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Section: Nature Of Subcontinental Lithospheric Mantlesupporting

confidence: 81%

Section: Nature Of Subcontinental Lithospheric Mantlesupporting

confidence: 55%

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

Sahu

Gupta²,

Patel³

et al. 2013

Proceedings of 10th International Kimberlite Conference

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show abstract

“…Graphite along grain boundaries is another possible explanation for the feature MC2 as this is largely well within the graphite‐diamond stability field of ~160 km beneath the craton [ Patel et al ., ], beyond which graphite gets transformed to resistive diamond formation at higher pressure [ Kennedy and Kennedy , ]. However, according to Yoshino and Noritake [], graphite films may not be stable at temperatures >700°C and such temperature conditions are expected in the Dharwar craton at depths greater than ~ 80 km [e.g., Roy and Mareschal , ].…”

Section: Interpretation Of the Resistivity Structuresmentioning

confidence: 99%

The electrical resistivity structure of lithosphere across the Dharwar craton nucleus and Coorg block of South Indian shield: Evidence of collision and modified and preserved lithosphere

et al. 2015

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Magnetotelluric-derived two-dimensional lithospheric resistivity structure of the western Dharwar craton (WDC) and adjoining Coorg block indicates isolated low-resistivity zones in the crust and three striking upper mantle conductive features within the highly resistive Archean lithosphere. The crustal conductors in the WDC show good spatial correlation with the exposed supracrustal rocks conformable with the relic schist belt channels having conductive mineral grains. Conductive zones within the Coorg crust might be related to the relatively young (933 Ma) metamorphic processes in the area and/or possible fluids derived from the Cretaceous passage of Reunion plume in the proximity of Coorg area. A near-vertical conductive structure extending from the lower crust into the upper mantle coincides with the transition zone between Coorg and WDC. This is interpreted as the suture zone between the two tectonic blocks and provides evidence for the individuality of the two Archean terrains. An anomalous upper mantle conductive zone found beneath the craton nucleus may indicate a modified cratonic lithosphere. This could have been derived due to the collision between Coorg and WDC and possibly survived by the subsequent multiple episodes of melt and fluid infiltration processes experienced in the region. Thick (~190 km) and preserved lithosphere is mapped at the eastern segment of WDC. Resistive lithosphere of~125 km thickness is imaged for the Coorg block.

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“…This is taken to indicate that some of the clinopyroxenes with high Mg numbers equilibrated with coexisting garnet and chromite in the mantle source region. However, the CCGE trend is not reflected by concentrate garnets from the same southern Indian kimberlites (Patel et al, 2010). Clinopyroxenes in MARID-type xenoliths from southern Indian kimberlites have Mg number in the range of 0.81-0.84 and are Fe-richer than the concentrate clinopyroxenes (Fig.…”

Section: Clinopyroxene Compositionmentioning

confidence: 96%

Clinopyroxene macrocrysts in Proterozoic kimberlites from southern India

International Kimberlite Conference Extended Abstracts: 2012

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Major element composition of concentrate garnets in Proterozoic kimberlites from the Eastern Dharwar Craton, India: Implications on sub-continental lithospheric mantle

Cited by 9 publications

References 33 publications

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

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

The electrical resistivity structure of lithosphere across the Dharwar craton nucleus and Coorg block of South Indian shield: Evidence of collision and modified and preserved lithosphere

Clinopyroxene macrocrysts in Proterozoic kimberlites from southern India

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