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Titre du document / Document title

Mesoproterozoic diamondiferous ultramafic pipes at Majhgawan and Hinota, Panna area, central India : Key to the nature of sub-continental lithospheric mantle beneath the Vindhyan basin

Auteur(s) / Author(s)

CHALAPATHI RAO N. V. (1) ;

Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)

(1) EPMA Laboratory, Mineralogy Section, Ore Dressing Division, Indian Bureau of Mines, Nagpur 440 016, INDE

Résumé / Abstract

Amongst all the perceptible igneous manifestations (volcanic tuffs and agglomerates, minor rhyolitic flows and andesites, dolerite dykes and sills near the basin margins, etc.) in the Vindhyan basin, the two Mesoproterozoic diamondiferous ultramafic pipes intruding the Kaimur Group of sediments at Majhgawan and Hinota in the Panna area are not only the most conspicuous but also well-known and have relatively deeper mantle origin. Hence, these pipes constitute the only yet available 'direct' mantle samples from this region and their petrology, geochemistry and isotope systematics are of profound significance in understanding the nature of the sub-continental lithospheric mantle beneath the Vindhyan basin. Their emplacement age (∼1100 Ma) also constitutes the only reliable minimum age constrain on the Lower Vindhyan Group of rocks. The Majhgawan and Hinota pipes share the petrological, geochemical and isotope characteristics of kimberlite, orangeite (Group II kimberlite) and lamproite and hence are recognised as belonging to a 'transitional kimberlite-orangeite-lamproite' rock type. The name majhagwanite has been proposed by this author to distinguish them from other primary diamond source rocks. The parent magma of the Majhgawan and Hinota pipes is envisaged to have been derived by very small (<1%) degrees of partial melting of a phlogopite-garnet lherzolite source (rich in titanium and barium) that has been previously subjected to an episode of initial- depletion (extensive melting during continent formation) and subsequent metasomatism (enrichment). There is absence of any subduction-related characteristics, such as large negative anomalies at Ta and Nb, and therefore, the source enrichment (metasomatism) of both these pipes is attributed to the volatile- and K-rich, extremely low-viscosity melts that leak continuously to semi-continuously from the asthenosphere and accumulate in the overlying lithosphere. Lithospheric/crustal extension, rather than decompression melting induced by a mantle plume, is favoured as the cause of melting of the source regions of Majhgawan and Hinota pipes. This paper is a review of the critical evaluation of the published work on these pipes based on contemporary knowledge derived from similar occurrences elsewhere.

Revue / Journal Title

Journal of earth system science    ISSN  2347-4327 

Source / Source

2006, vol. 115, no 1 (184 p.)  [Document : 23 p.] (3 p.3/4), pp. 161-183 [23 page(s) (article)]

Langue / Language

Anglais

Editeur / Publisher

Springer, Heidelberg, ALLEMAGNE  (2007) (Revue)

Mots-clés anglais / English Keywords

Asia

;

Vindhyan Basin

;

India

;

extension

;

lithosphere

;

asthenosphere

;

melts

;

viscosity

;

volatiles

;

anomalies

;

subduction

;

enrichment

;

metasomatism

;

continents

;

depletion

;

barium

;

titanium

;

partial melting

;

magmas

;

source rocks

;

diamonds

;

emplacement

;

isotopes

;

mantle origin

;

sills

;

agglomerate

;

mantle

;

pipes(igneous rocks)

;

Mots-clés français / French Keywords

Asie

;

Bassin Vindhyan

;

Inde

;

Extension

;

Lithosphère

;

Asthénosphère

;

Matière fondue

;

Viscosité

;

Matière volatile

;

Anomalie

;

Subduction

;

Enrichissement

;

Métasomatisme

;

Continent

;

Appauvrissement

;

Baryum

;

Titane

;

Fusion partielle

;

Magma

;

Roche mère

;

Diamant commercial

;

Mise en place

;

Isotope

;

Origine mantellique

;

Sill

;

Agglomérat

;

Manteau

;

Pipe

;

Mots-clés espagnols / Spanish Keywords

Asia

;

Cuenca Vindhyan

;

India

;

Extensión

;

Litosfera

;

Astenosfera

;

Producto fundido

;

Viscosidad

;

Materia volátil

;

Anomalía

;

Subducción

;

Enriquecimiento

;

Bario

;

Titanio

;

Fusión parcial

;

Magma

;

Roca madre

;

Diamante comercial

;

Emplazamiento

;

Isótopo

;

Sill

;

Aglomerado

;

Abrigo

;

Pipa

;

Localisation / Location

INIST-CNRS, Cote INIST : 573 A2, 35400013889192.0110

Nº notice refdoc (ud4) : 17945660



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