Sm-Nd Isotopic and Geochemical Study of the Archean Tonalite-Amphibolite association from the eastern Indian Craton

Sharma, Mukul; Basu, Asish R.; Ray, Suman

doi:10.1007/bf00307728

Cited by 107 publications

(55 citation statements)

References 51 publications

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“…The oldest rocks in this craton are the amphibolite-tonalite gneiss association called the older metamorphic group (OMG) with an age ~3.3 Ga (Sharma et al, 1994). A major part of this craton is occupied by the Singhbhum granite batholith complex covering an area of about 10,000 km 2 .…”

Section: Geologic Settingmentioning

confidence: 99%

Sm-Nd age and mantle source characteristics of the Dhanjori volcanic rocks, Eastern India.

et al. 2002

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Section: Geologic Settingmentioning

confidence: 99%

Sm-Nd age and mantle source characteristics of the Dhanjori volcanic rocks, Eastern India.

et al. 2002

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“…The mid-Proterozoic Eastern Ghat Granulite belt is in the southwest and the relatively high-grade metamorphic Satpura Orogenic belt of middle Proterozoic age is situated to the northwest of the craton. The Singhbhum Granite batholithic complex of 3292 þ 51 Ma age [14,15] occupies the major portion of this craton. Remnants of ancient rocks that include the Older Metamorphic Group (OMG), which consists of meta-igneous and meta-sedimentary rocks of amphibolite facies [16], and the Older Metamorphic Tonalite Gneisses (OMTG) are found within the batholithic complex.…”

Section: Geologic Settings and Samples For This Studymentioning

confidence: 99%

“…Subhedral tourmaline grains and elongate-elliptical zircon are common accessories in these pelitic schists [12,22]. The tonalites of the OMTG, which intrude the OMG, consist mainly of plagioclase and quartz with biotite and occasional hornblende [11,13,15]. The Singhbhum Granite, varying from basic granodiorite through adamellite to acid potassic granite, comprises plagioclase, quartz, orthoclase, and chloritized hornblende and mica.…”

Section: Lithology Of the Source Areamentioning

confidence: 99%

“…1 to the REE patterns of the amphibolites of the OMG and the tonalites from the OMTG. REE data determined previously [15] by neutron activation analysis are available for eight amphibolites and seven tonalites from the adjacent region of this craton (Fig. 1).…”

Section: Trace Element Geochemistrymentioning

confidence: 99%

“…However, all the amphibolites show a £at HREE pattern with (Gd/Lu) N varying between 0.9 and 1.2. The average REE concentrations of the amphibolites and tonalites (averaged from 8 amphibolites and 7 tonalites from [15]) are shown in Fig. 4 (¢lled symbols, inset).…”

Section: Trace Element Geochemistrymentioning

confidence: 99%

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Geochemical and petrological evidence for subduction–accretion processes in the Archean Eastern Indian Craton

Saha

Basu

Garzione

et al. 2004

Earth and Planetary Science Letters

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The composition of sandstones often provides key evidence about the tectonic, weathering and transport processes operating on the surface at the time of deposition. Petrologic and geochemical analyses of little-metamorphosed middle^late Archean sandstones from the Eastern Indian Craton show that the sedimentary rocks were derived from dominantly 3.3-Ga-old amphibolites of the Older Metamorphic Group (OMG) and tonalites of the Older Metamorphic Tonalite Gneisses (OMTG), the two oldest lithologic units of this craton. Chondrite-normalized rare earth element (REE) patterns of the sandstones show a light REE-enriched signature with (La/Sm) N varying from 5.2 to 6.7 with no Eu anomaly, while the heavy REEs display flat patterns with (Gd/Lu) N values of 0.9^1.6. Primitive mantle-normalized incompatible and compatible trace element plots of these sandstones demonstrate an overall similarity with global Proterozoic^Archean sandstones, including strong Nb^Ta negative anomalies. In an f Sm=Nd vs. O Nd (0) diagram, the sandstones plot precisely between the regional amphibolites and tonalites. We infer from the REE abundances and the f Sm=Nd vs. O Nd (0) plot that the sandstones represent a bimodal mechanical mixture of OMG and OMTG. The low Ce/Pb ratios of these rocks of 1^4 indicate a variably Pb-enriched Archean crust and that the Ce/Pb ratio acquired the continental crustal signature, distinctly different from those of the bulk silicate earth and mantle values at least as early as mid-Archean. Strong Nb^Ta depletion relative to the primitive mantle suggests the sandstones were derived from subduction-related magmatic arc sources. This latter suggestion is strongly supported by the low Nb/Ta and high Zr/Sm ratios of these sandstones, identical to Archean tonalite^trondhjemites that require, based on recent trace-element partitioning results, their protoliths to have formed by subduction melting of lowmagnesium amphibolites or metamorphosed hydrous basalts [1,2]. The average Nd model ages of the sandstones are greater than the Sm^Nd crystallization ages of the OMG and OMTG at V3.3 Ga. The geochemical data presented here can be collectively interpreted to suggest the presence of subduction^accretion processes operational in the midArchean Eastern Indian Craton. Because the OMG and OMTG, the source rocks of the sandstones, formed in a subduction-related arc setting, the basement rocks upon which this arc was constructed must have been older. This observation and the depleted mantle Nd model ages (T DM ) of the sandstones, ranging from 3.6 to 4.0 Ga, strongly indicate the presence of continental crust in this Eastern Indian craton older than 3.3 Ga and possibly as old as 0012-821X / 04 / $^see front matter ß

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Vestiges of older greenstone in Mesoarchaean Chakradharpur granite gneiss, Singhbhum Craton, India: Implications for plume‐lithosphere interaction at rifted cratonic margin

Ghose

Saha

2018

Geological Journal

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The Chakradharpur granite gneiss (CGG) represents an uplifted Archaean basement within the North Singhbhum Orogen (NSO) of Singhbhum‐Orissa Craton in the eastern Indian shield and shares a Mesoarchaean 3.12 Ga age equivalent to the emplacement of Singhbhum granite (SBG) phase III. The CGG hosts numerous enclaves of tonalitic gneisses, metamorphosed ultramafic and mafic volcanics, metagabbros, metasediments, and conglomerates that collectively represent vestiges of an older greenstone belt preserved within it. The mineralogical composition of the ultramafic volcanic enclaves of CGG has been overprinted by greenschist facies metamorphism presenting a talc‐tremolite‐phlogopite‐actinolite assemblage with prominent development of crenulation cleavage, pressure solutions and relict spinifex texture. These are characterised by restricted low SiO2 (39.7–46.8 wt.%) at consistently high MgO (20.7–28 wt.%) contents, and geochemically classified as: (a) subalkaline (Na2O + K2O < 2) komatiite and meimechite and (b) an alkaline (Na2O + K2O > 2) type picrobasalt‐foidite‐basanite assemblage. Depleted LILE and LREE chemistry, Al2O3/TiO2 versus (Gd/Yb)N and HFSE abundances suggest that the studied Al‐undepleted Munro‐type komatiite and meimechite were derived by high degree (30%–50%), shallow level (<90 km) partial melting of a hot, anhydrous mantle plume carrying depleted components. It is suggested that the komatiite‐meimechite melts were deflected by an Archaean cratonic keel and erupted through thinned continental lithosphere at a rifted cratonic margin. Geochemical evidence of crustal contamination preserved in these komatiites are equated with minor input from reworking of older continental materials and interaction between plume‐derived asthenospheric melts and metasomatized subcontinental lithospheric mantle (SCLM). Zr/Hf, Zr/Sm, Nb/Ta, Zr/Nb, and Nb/Th ratios for the picrobasalt, high Mg basalt, foidite and basanite rocks corroborate their generation through variable degrees of partial melting of a heterogeneous lithospheric mantle source carrying depleted plume‐derived melts and enriched components from metasomatized lithosphere. Mantle processes involved assimilation of metasomatic components of SCLM by ascending melts of plume incubating at the base of lithosphere ensued by melt generation at different mantle depths extending from garnet to spinel peridotite domains. Therefore, the geochemical signatures of ultramafic enclaves in CGG invoke distinct magmatic episodes during plume‐craton interaction, melt generation at thinned craton margin to rifted continental interior and melting of metasomatized continental lithosphere that collectively contributed to the evolution of Archaean mantle lithosphere system, volcanism with diverse chemical compositions and greenstone generation in the Singhbhum Craton.

show abstract

Sm-Nd Isotopic and Geochemical Study of the Archean Tonalite-Amphibolite association from the eastern Indian Craton

Cited by 107 publications

References 51 publications

Sm-Nd age and mantle source characteristics of the Dhanjori volcanic rocks, Eastern India.

Sm-Nd age and mantle source characteristics of the Dhanjori volcanic rocks, Eastern India.

Geochemical and petrological evidence for subduction–accretion processes in the Archean Eastern Indian Craton

Vestiges of older greenstone in Mesoarchaean Chakradharpur granite gneiss, Singhbhum Craton, India: Implications for plume‐lithosphere interaction at rifted cratonic margin

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