Petrogenesis of basalt–high-Mg andesite–adakite in the Neoarchean Veligallu greenstone terrane: Geochemical evidence for a rifted back-arc crust in the eastern Dharwar craton, India

Khanna, Tarun C.; Sai, V. V. Sesha; Bizimis, Michael; Krishna, A. Keshav

doi:10.1016/j.precamres.2015.01.004

Cited by 25 publications

(23 citation statements)

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“…Trace elements (Table 1) including large ion lithophile elements (LILE), high field strength elements (HFSE) and rare earth elements (REE) were determined by high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS; Nu Instruments Attom  , UK). The detailed procedures relating to sample dissolution, analytical methodology and instrument parameters are described in Khanna et al (2015Khanna et al ( , 2016. In brief, 50 mg of finely ground sample powder was digested in a freshly prepared mixture of ultrapure grade acids (HF +HNO3) taken in 3:1 ratio in screw top Teflon "Savillex" vessels, and heated on a hot plate at 160°C.…”

Section: Sampling and Analytical Methodsmentioning

confidence: 99%

“…Recently, Khanna et al (2015) presented a detailed account of the geology, petrography and geochemistry of the metavolcanic rocks comprising of basalt, high-Mg andesite and adakite in the Veligallu terrane. The authors have shown that these volcanic rocks were generated in response to subduction-related arc magmatic processes presumably in a Neoarchean back-arc setting.…”

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confidence: 99%

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Petrogenesis of ultramafics in the Neoarchean Veligallu greenstone terrane, eastern Dharwar craton, India: Constraints from bulk-rock geochemistry and Lu-Hf isotopes

Khanna

Sai

Bizimis

et al. 2016

Precambrian Research

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We report on the bulk-rock geochemistry and Lu-Hf isotope systematics, and infer the petrogenesis of the ultramafic rocks in the Neoarchean Veligallu greenstone terrane, eastern Dharwar craton, India. The ultramafics along with the basalts and adakites yield an age of 2.696 ± 0.054 Ga, consistent with the available SIMS zircon U-Pb age of 2.697 ± 5 Ma, reported for the felsic volcanics, in the literature. The rocks have positive initial εHf (2.696 Ga) = + 3.0 to + 6.5, consistent with an origin from a long term depleted mantle source relative to a chondritic reservoir at ~2.7 Ga. Geochemically, the ultramafic rocks are characterized by high MgO = 23-33 wt. %, Mg# ~ 89, Cr = 2290-3855 ppm and Ni = 604-966 ppm contents; moderate to low SiO2 = 52-49 wt. %, Al2O3 = 9.2-4.7 wt. %, and TiO2 = 0.30-0.14 wt. %. To first order, these chemical compositions broadly resemble komatiites. The rocks exhibit higher than chondrite Al2O3/TiO2 (21-37) ratio, depletions in their middle-REE relative to the heavy-REE i.e. GdN/YbN < 1, and negative Nb, Ti, and positive Zr (Hf) anomalies in a primitive mantle normalized trace element variation diagram. Hence, the Veligallu ultramafics lack the key geochemical characteristics that would indicate a plume origin typically attributed to komatiites. Post-magmatic low grade metamorphism, hydrothermal alteration and element mobility, and /or contamination by Archean upper continental crust cannot be the cause of these geochemical patterns. Further, the calculated liquid evolution lines involving major element chemistry, are inconsistent with a boninitic lineage. Present study suggests that the Veligallu ultramafic rocks may represent melts that mainly evolved through fractional crystallization of orthopyroxene ± olivine. The spatial and temporal association of these ultramafics with the arc basalts, andesites and adakites in the Veligallu greenstone terrane significantly contributes to the

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Section: Sampling and Analytical Methodsmentioning

confidence: 99%

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confidence: 99%

Petrogenesis of ultramafics in the Neoarchean Veligallu greenstone terrane, eastern Dharwar craton, India: Constraints from bulk-rock geochemistry and Lu-Hf isotopes

Khanna

Sai

Bizimis

et al. 2016

Precambrian Research

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“…The procedure is described in [15]. In brief, 50 mg of finely ground sample powder was digested in a freshly prepared mixture of ultrapure HF and HNO 3 at 3:1 ratio, in screw top Teflon "Savillex" vessels (Savillex Corporation, Minnesota, USA), and heated on a hot plate at 160 • C. Certified reference material BHVO-1 (supplied by United States Geological Survey, Reston, VA, USA), was dissolved simultaneously and then analyzed along with the samples.…”

Section: Sampling and Analytical Methodsmentioning

confidence: 99%

Boninites in the ~3.3 Ga Holenarsipur Greenstone Belt, Western Dharwar Craton, India

et al. 2018

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Abstract:In this contribution, we present detailed field, petrography, mineral chemistry, and geochemistry of newly identified high-Si high-Mg metavolcanic rocks from the southern part of the~3.3 Ga Holenarsipur greenstone belt in the western Dharwar craton, India. The rocks occur as conformable bands that were interleaved with the mafic-ultramafic units. The entire volcanic package exhibits uniform foliation pattern, and metamorphosed under greenschist to low grade amphibolite facies conditions. The rocks are extremely fine grained and exhibit relict primary igneous textures. They are composed of orthopyroxene and clinopyroxene phenocrysts with serpentine, talc, and amphibole (altered clinopyroxene). Cr-spinel, rutile, ilmenite, and apatite occur as disseminated minute grains in the groundmass. The mineralogical composition and the geochemical signatures comprising of high SiO 2 (~53 wt. %), Mg# (~83), low TiO 2 (~0.18 wt. %), and higher than chondritic Al 2 O 3 /TiO 2 ratio (~26), reversely fractionated heavy rare earth elements (REE) (Gd N /Yb N~0 .8), resulting in concave-up patterns, and positive Zr anomaly, typically resembled with the Phanerozoic boninites. Depletion in the high field strength elements Nb, and Ti relative to Th and the REE in a primitive mantle normalized trace element variation diagram, cannot account for contamination by pre-existing Mesoarchean continental crust present in the study area. The trace element attributes instead suggest an intraoceanic subduction-related tectonic setting for the genesis of these rocks. Accordingly, the Holenarsipur high-Si high-Mg metavolcanic rocks have been identified as boninites. It importantly indicates that the geodynamic process involved in the generation of Archean boninites, was perhaps not significantly different from the widely recognized two-stage melt generation process that produced the Phanerozoic boninites, and hence provides compelling evidence for the onset of Phanerozoic type plate tectonic processes by at least~3.3 Ga, in the Earth's evolutionary history.Keywords: boninite; komatiite; Mesoarchean; Holenarsipur; Dharwar craton; India IntroductionBoninites, and boninite-series volcanic rocks have been widely recognized in the Phanerozoic intraoceanic arc systems [1,2], and the Ophiolites, [3,4]. They are produced by the partial melting of a prior depleted refractory mantle wedge, metasomatized by subducted slab-derived fluids during the initial stages of the melt generation process. Their reported occurrence in the Archean greenstone successions is not very extensive. Nevertheless, there are some classical examples of boninitic magmatism that has been identified in the~3.7 Ga Eoarchean [5],~3.1 Ga Mesoarchean [6], and the~2.7 Ga Neoarchean [7,8] greenstone terranes.In this contribution, we present detailed field, petrography, and geochemistry of the newly identified high-Si high-Mg volcanic rocks from one of the oldest supracrustal sequences of late Paleoarchean age in the Dharwar craton, India. The rocks exhibit typical boninite geochem...

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“…(e.g. Kerrich et al, 1998;Hollings and Kerrich, 2000;Wyman et al, 2000, Polat andKerrich, 2004;Hollings, 2002;Percival et al, 2003;Polat and Hofmann, 2003;Shchipansky et al, 2004;Polat and Kerrich, 2006;Ujike et al, 2007;Manikyamba et al, 2009;Khanna et al, 2015). The main purpose of this study is to provide an interpretation of the tectonic setting of the Faina and Serra de Santa Rita greenstone belts, located in the southern portion of the Archean-Paleoproterozoic Terrane of Goiás, based on new geochemical and isotopic data of metavolcanic and metaplutonic rocks.…”

Section: Introductionmentioning

confidence: 95%

“…11. Th/Nb vs. Ce/Nb discriminat diagram (modified after Saunders et al, 1988 andKhanna et al, 2015) for amphibolites of the type 1 basalts group of the Serra de Santa Rita greenstone belt; these rocks plot in the Phanerozoic Mariana back-arc basalts field (BABB; Pearce et al, 2005). Abreviations: DMM (depleted MORB mantle component); SDC (subduction zone component).…”

Section: Type 1 Basalts: Back-arc Basin Basalts (Babb)mentioning

confidence: 99%

Petrografia, geoquímica e geocronologia das rochas metavulcânicas e metaplutônicas dos Greenstone Belts faina e Serra de Santa Rita : implicações para o ambiente tectônico

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Agradeço primeiramente a Deus. Agradeço aos meus pais, Divino Borges e Luciene Aguiar, e a minha irmã, Suellen, por todo o apoio, dedicação, ensinamentos e advertências, e por serem meu grande exemplo de sucesso. Agradeço as minhas orientadoras, Catarina e Adalene, pela confiança, motivação, apoio, paciência e amizade, e por me ajudarem a crescer como aluno e como pessoa. Agradeço aos professores Hardy, Farid e Jeremie, pelas contribuições a este trabalho e pelas enriquecedoras discussões geológicas. Agradeço a todos os professores e funcionários do Instituto de Geociências da UnB. Agradeço a todos os participantes do TF-2014, por todas as contribuições, amizades e parcerias durante o campo. Agradeço a todos os meus grandes amigos da Geologia. Agradeço ao CNPq, pela bolsa de mestrado.

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Petrogenesis of basalt–high-Mg andesite–adakite in the Neoarchean Veligallu greenstone terrane: Geochemical evidence for a rifted back-arc crust in the eastern Dharwar craton, India

Cited by 25 publications

References 66 publications

Petrogenesis of ultramafics in the Neoarchean Veligallu greenstone terrane, eastern Dharwar craton, India: Constraints from bulk-rock geochemistry and Lu-Hf isotopes

Petrogenesis of ultramafics in the Neoarchean Veligallu greenstone terrane, eastern Dharwar craton, India: Constraints from bulk-rock geochemistry and Lu-Hf isotopes

Boninites in the ~3.3 Ga Holenarsipur Greenstone Belt, Western Dharwar Craton, India

Petrografia, geoquímica e geocronologia das rochas metavulcânicas e metaplutônicas dos Greenstone Belts faina e Serra de Santa Rita : implicações para o ambiente tectônico

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