RbSr ages of Late Archean metavolcanics and granites, Dharwar craton, South India and evidence for Early Proterozoic thermotectonic event(s)—reply

Rao, Y. J. Bhaskar; Sivaraman, T.V.; Pantulu, G. V. C.; Gopalan, K.; Naqvi, S. M.

doi:10.1016/0301-9268(94)90071-x

Cited by 10 publications

(7 citation statements)

References 27 publications

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“…More recently, Ishwar Kumar et al (2013) have reported U-Pb SHRIMP ages of ∼2.57 Ga for quartzo-feldspathic gneisses from the Dharwar block. Similar ages (2.6-2.5 Ga, CHIME-monazite) were obtained by Rekha et al (2013) Pb whole-rock isochron age of 2565 5 28 Ma (Taylor et al 1984) and an Rb-Sr isochron age of 2520 5 62 Ma (Bhaskar Rao et al 1992 Pb whole-rock isochron age of 2605 5 18 Ma (Taylor et al 1984) and a U-Pb zircon age of 2614 5 10 Ma (Jayananda et al 2006). Felsic volcanism and granitic intrusion in the Gadag greenstone belt has been dated at 2588 5 10 and 2570 5 10 Ma, respectively (U-Pb zircon; Sarma et al 2011).…”

Section: Discussionsupporting

confidence: 50%

The Basement of the Deccan Traps and Its Madagascar Connection: Constraints from Xenoliths

Upadhyay

Kooijman

Singh

et al. 2015

The Journal of Geology

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Section: Discussionsupporting

confidence: 50%

The Basement of the Deccan Traps and Its Madagascar Connection: Constraints from Xenoliths

Upadhyay

Kooijman

Singh

et al. 2015

The Journal of Geology

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“…Based on the tectono‐thermal and magmatic history, crustal thickness, structure and age, the Dharwar Craton has been divided into the WDC and the Eastern Dharwar Craton (EDC) (Bhaskar Rao et al, 1992; Chardon & Jayananda, 2008; Gupta et al, 2003; Sundar Raju et al, 2014; Swami Nath et al, 1976), while Naha et al (1986, 1990), based on structural similarity negate suturing of the EDC and WDC. Maibam et al (2017) and Singh et al (2021) also arrived at similar inferences based on geochronological data.…”

Section: Geological Backgroundmentioning

confidence: 99%

“…Subsequently, these rocks were metamorphosed and intruded by acidic magmas around 3.13–2.96 Ga, which formed the protoliths of the Peninsular Gneiss Complex (PGC) (Peucat et al, 1993; Ramakrishnan & Swaminatha, 1976). The PGC is a polyphase gneiss complex that was formed by dynamo‐thermal metamorphism of the older pre‐Dharwar sedimentary‐volcanic sequence and partial melting of mafic crust (Bhaskar Rao et al, 1992; Gupta et al, 2003; Jayananda et al, 2015, 2018; Maibam et al, 2011, 2016). Formation of the PGC and its stabilization lasted for almost 0.5 billion years, beginning with polyphase gneisses and emplacement of tonalite‐trondhjemite‐granodiorite (TTG) suites and ending with late‐stage voluminous granite plutons from 3.2 to 2.5 Ga (Chadwick et al, 1981; Corfu & Hegde, 2020; Jayananda et al, 2015; Figure 1b).…”

Section: Geological Backgroundmentioning

confidence: 99%

Provenance of the conglomerate and siliciclastic rocks from the Gadag Greenstone Belt, Western Dharwar Craton, India: Implications for understanding Neoarchean basin margin sedimentation

et al. 2023

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whole-rock geochemical and geochronological analysis of polymictic conglomerate, associated siltstone and greywacke in the Neoarchean Gadag Greenstone Belt in the Western Dharwar Craton, India, provides new insights into sedimentary provenance and tectonic setting. The polymictic conglomerate contains granitic, gneissic, felsic and mafic volcanic, quartzite and banded ferruginous chert clasts within a quartzofeldspathic matrix. Framework grains in the siltstone and greywacke are quartz, feldspar with rock fragments, embedded in a chlorite-dominant matrix. The chemical index of alteration values ($70) and A-CN-K plot for the rocks suggest a low-to-moderate degree of weathering. Rare earth element (REE) patterns show moderate fractionation (La N /Yb N $ 12.31) with a weak negative europium anomaly (0.82). Enrichment in transition elements (Ni, Cr, Co, Sc) and depletion in high-field-strength elements, as well as relatively low La/Co (0.62), moderate to high Th/Yb (3.06), La/Th (5.16), La/Yb (17.5), and La/Sc ($2.37) ratios, suggest a mixed felsic-mafic provenance. U-Pb dating of detrital zircon from the conglomerate and greywacke revealed major age peaks at ca. (3.2, 2.9, 2.8, 2.6, 2.5 Ga) and a maximum age of deposition of 2,508 ± 26 Ma, 2,493 ± 20 Ma, respectively. The above data suggest low to moderately weathered proximal sources for both conglomerate and greywacke, indicating that these two rock types were not deposited simultaneously, but rather separately. The association of these conglomerates and greywacke with continental arc-related volcanics indicates the closing of an arc at the time of sedimentation. Complex provenance consisting of recycled and magmatic arc during basin closure confirm the notion of modern style plate tectonics operating during Neoarchaean.

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“…The WDC comprises TTG-type gneisses and greenstone belts, which are separated into the older Sargur Group and the younger Dharwar Supergroup (Chadwick et al, 2000;Jayananda et al, 2006, 2015, andreferences therein). The Peninsular Gneisses (TTG) resulted from accretion in several stages between 3.36 and 3.2 Ga (Meen et al, 1992;Bhaskar Rao et al, 1992;Peucat et al, 1993;Jayananda et al, 2015Jayananda et al, , 2018Santosh et al, 2015). The Sargur Group greenstone belt comprises predominantly komatiite and basalt, constrained by a Sm-Nd whole rock isochron age of 3352 ± 110 Ma (Jayananda et al, 2008), while a more precise U-Pb zircon age of 3298 ± 7 Ma has been obtained on the subordinate felsic volcanic rocks (Peucat et al, 1995).…”

Section: Geological Outline Of the Dharwar Cratonmentioning

confidence: 99%

Neoarchaean Felsic Volcanic Rocks in Tracing Evolution of Arcs: An Insight from Geochemical Data of the Gadag Schist Belt, Western Dharwar Craton

Hedge

Corfú

Frimmel

et al. 2021

Journal of the Geological Society of India

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Quartz porphyry of rhyolitic composition is a volumetrically minor but important component of metavolcanic successions in the Gadag schist belt in the Western Dharwar Craton. The quartz porphyries are calc-alkaline, enriched in light rare earth elements (Lan/Ybn ~ 10-20) and with a strong negative Eu anomaly (Eu/Eu*N = 0.45-0.58). These features, coupled with high K2O/Na2O (0.8 1.46), low Nb/Th (<1), and Lan/Smn ratios of 4.2 to 6.0, suggest that rhyolitic magma formed from melt generated by partial melting of basaltic crust, subsequently modified by crustal assimilation and by crystal fractionation. The geological setting of the quartz porphyries and the geochemical relationships suggest magmatism at a convergent plate tectonic setting. The zircon U-Pb age of 2588.0 ± 2.4 Ma for the quartz porphyry, together with an age of 2732 Ma for similar volcanic rocks in the Chitradurga schist belt further south, and 2614 Ma for felsic volcanics from the Shimoga schist belt, point to an extended period with episodic arc magmatism in the Western Dharwar Craton of at least ~144myr.

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RbSr ages of Late Archean metavolcanics and granites, Dharwar craton, South India and evidence for Early Proterozoic thermotectonic event(s)—reply

Cited by 10 publications

References 27 publications

The Basement of the Deccan Traps and Its Madagascar Connection: Constraints from Xenoliths

The Basement of the Deccan Traps and Its Madagascar Connection: Constraints from Xenoliths

Provenance of the conglomerate and siliciclastic rocks from the Gadag Greenstone Belt, Western Dharwar Craton, India: Implications for understanding Neoarchean basin margin sedimentation

Neoarchaean Felsic Volcanic Rocks in Tracing Evolution of Arcs: An Insight from Geochemical Data of the Gadag Schist Belt, Western Dharwar Craton

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