Hornblende-dehydration melting in mafic rocks and the link between massif-type charnockite and associated granulites, Eastern Ghats Granulite Belt, India

Kar, Rajib; Bhattacharya, S.; Sheraton, J. W.

doi:10.1007/s00410-003-0468-8

Cited by 37 publications

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“…Our petrogenetic studies indicate charnockitic melt as product of partial melting in mafic rocks under granulite facies conditions [9,15,21]. Hence the protoliths of the charnockite-gneiss are mafic rocks, now represented by the hornblende-mafic granulites.…”

mentioning

confidence: 77%

“…Isoclinal and rootless F 1 folds with a NE-SW trending steep axial-plane foliation, S 1 and common structural repetitions suggest a regional NW-SE directed compression and shortening during the development of first generation folds [4]. Beside the polyphase deformation history, the Eastern Ghats Belt is also characterized by polycyclic metamorphic record and dehydration melting in different crustal protoliths [5][6][7][8][9]. However, in view of different crustal residence ages from different parts of the regional granulite terrain, as also distinct isotopic records of granulite facies metamorphism across this regional granulite terrain, the tectonic-metamorphic evolution should be discussed separately for the different crustal domains & provinces identified [10,11].…”

Section: Geological Backgroundmentioning

confidence: 99%

“…And the earliest granulite metamorphism at 1.2 Ga involved both the mafic rocks and the supracrustal rocks. High to ultra-high temperature granulite metamorphism of the mafic rocks produced the charnockitic melt by partial melting [9,21,29]. And the same high to ultra-high temperature granulite metamorphism of the supracrustal rocks (including khondalites and high-Mg-Al granulites) produced the peraluminous granitoids [7,8,30].…”

Section: Geochronologymentioning

confidence: 99%

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Relative Chronology in High-Grade Crystalline Terrain of the Eastern Ghats, India: New Insights

Bhattacharya

Kar²,

Saw

et al. 2011

IJG

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The two major lithology or gneiss components in the polycyclic granulite terrain of the Eastern Ghats, India, are the supracrustal rocks, commonly described as khondalites, and the charnockite-gneiss. Northern Eastern Ghats belt, north of the Godavari rift has been defined as the Eastern Ghats Province, while that to the south has been defined as the Ongole domain; and although, these distinct crustal domains also record different ages of granulite metamorphism, both of these domains are dominated by the two lithologies. Many of the workers considered the khondalites as the oldest component with unknown basement and the charnockiteprotoliths as intrusive into the khondalites. However, published geochronological data do not corroborate the aforesaid relations. Onset of khondalite sedimentation in the Proterozoic Eastern Ghats Province, constrained by detrital zircon data, as around 1.3 Ga and the charnockite-protolith emplacement between 1.9 and 2.9 Ga, argue against intrusion of felsic magma (tonalite, now enderbite!) in to the khondalites. The field relations of the hornblende-mafic granulite with the two gneiss components together with Sm-Nd isotopic data of the hornblende-mafic granulites (both the xenoliths within charnockites and those interbanded with the khondalites) indicate that khondalite sediments were deposited on older mafic crustal rocks. Mafic basement and supracrustal rocks were subsequently deformed and metamorphosed together during collisional orogeny at high to ultra-high temperatures-partial melting of mafic rocks producing the charnockitic melt; and partial melting of pelitic sediments producing the peraluminous granitoids. This is compatible with all the geochronological data as well as the petrogenetic model of partial melting for the charnockitic rocks in the Eastern Ghats Belt. The Ongole domain, south of the Godavari rift, though, is distinct in terms of the age of first/ earliest UHT metamorphism, but here too the charnockite-protoliths are older mafic rocks evidently not intrusive in to the khondalites..

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confidence: 77%

Section: Geological Backgroundmentioning

confidence: 99%

Section: Geochronologymentioning

confidence: 99%

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Relative Chronology in High-Grade Crystalline Terrain of the Eastern Ghats, India: New Insights

Bhattacharya

Kar²,

Saw

et al. 2011

IJG

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“…From the Jenapore area in the Eastern Ghats Belt, India, charnockite-massif was described as the product of hornblende-dehydration melting under granulite facies conditions, and with residual hornblende. There the two-pyroxene granulites occur as minor patches and bands and were explained as peritectic segregates [5]. A stock-like body of charnockite (pluton) occurs in the same locale, a few kilometer to the south (Lat: 20 o 46' N; Long: 86 o 05' E).…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, petrogenesis of massif-type charnockites have been variously described: a) mantlederived and differentiated melt [2]; b) high-temperature melting of dry granulite facies rocks [3]; c) more mafic varieties as mantle-derived melts [4]; d) product of hornblende-dehydration melting in the deep crust [5]. New melting experiments provide constraints on the petrogenesis of charnockitic rocks of dioritic composition.…”

Section: Introductionmentioning

confidence: 99%

New experimental constraints: implications for pe-trogenesis of charnockite of dioritic composition

Kar¹,

Bhattacharya²

2010

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Early Jurassic high‐Mg andesites in the Quxu area, southern Lhasa terrane: Implications for magma evolution related to a slab rollback of the Neo‐Tethyan Ocean

et al. 2018

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Over the past few years, an increasing number of Early Jurassic magmatic rocks have been found in the southern Lhasa terrane and well studied; however, high‐Mg andesitic rocks are considerably rare, and the Mesozoic palaeotectonic framework of Neo‐Tethyan Ocean remains controversial. The present study focuses on Early Jurassic high‐Mg andesites that outcropped in the Quxu area, southern Lhasa terrane. In the Quxu area, the Early Jurassic (189 Ma) volcanic sequences are mainly composed of andesites and basaltic andesites and are unconformably in contact with Late Triassic diorites (226 Ma). These volcanic rocks are characterized by SiO2 (49–58 wt.%), MgO (6.2–11.1 wt.%) and Mg# (61–69), TiO2 (0.48–0.76 wt.%) and TFeO/MgO ratios (0.80–1.13), with geochemical features similar to those of high‐Mg andesites. Their depleted mantle‐type Nd (εNd(t) = +4.9 to +6.9) and Hf (εHf(t) = +9.6 to +14.9) isotopic compositions, together with their geochemical characteristics, suggest that the Quxu high‐Mg andesites were most likely produced by the interaction between the asthenospheric mantle and lithospheric mantle that metasomatized by slab‐derived fluids. The diorites belong to metaluminous calc‐alkaline series with highly positive εHf(t) values (+13.4 to +15.8) and are interpreted to be produced mainly by partial melting of the juvenile crustal basaltic rocks with minor input from the depleted mantle. We speculate that, in combination with the distribution of the Mesozoic magmatic rocks in the southern Lhasa terrane, the rollback of the subducting Neo‐Tethyan Ocean was the prime reason for the Early Jurassic tectono‐magmatic evolution in the southern Lhasa terrane. This process facilitated a rapid linear upwelling of the asthenospheric mantle beneath the southern Lhasa terrane and ultimately led to the large‐scale magmatic flare‐ups. Furthermore, events associated with slab rollback likely played an important role in crustal growth in the southern Lhasa terrane.

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Hornblende-dehydration melting in mafic rocks and the link between massif-type charnockite and associated granulites, Eastern Ghats Granulite Belt, India

Cited by 37 publications

References 51 publications

Relative Chronology in High-Grade Crystalline Terrain of the Eastern Ghats, India: New Insights

Relative Chronology in High-Grade Crystalline Terrain of the Eastern Ghats, India: New Insights

New experimental constraints: implications for pe-trogenesis of charnockite of dioritic composition

Early Jurassic high‐Mg andesites in the Quxu area, southern Lhasa terrane: Implications for magma evolution related to a slab rollback of the Neo‐Tethyan Ocean

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