RbSr ages of Proterozoic kimberlites of India: evidence for contemporaneous emplacement

Kumar, Anil; Kumari, V.; Dayal, A. M.; Murthy, D. S. N.; Gopalan, K.

doi:10.1016/0301-9268(93)90023-u

Cited by 140 publications

(39 citation statements)

References 12 publications

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“…Presence of granulitic facies rocks at a shallow depth beneath EDC is hardly surprising, considering its past geologic history when it experienced extensive tectonothermal magmatic activities at around 2.7-2.2 Ga, 1.9-1.8 Ga, 1.2-1.1 Ga, and 0.85-0.5 Ga (Naqvi and Rogers, 1987;Rogers and Callahan, 1987;Acharya, 1997;Anil Kumar et al, 1993;Radhakrishna and Naqvi, 1986 etc.). The earliest activity (2.7-2.5 Ga) was caused by a rising mantle plume beneath a matured ancient crust which induced low degree melting of upper mantle resulting in generation and accretion of large quantity of calc-alkaline magmas observed in EDC (Jayananda et al, 2000;Harish Kumar et al, 2003).…”

Section: Discussion Of Results and Conclusionmentioning

confidence: 99%

“…In contrast, the EDC is characterised by late Archean-early Proterozoic (∼2.5 Ga) cratonic growth with low pressure metamorphism and remoblisation of crustal blocks, containing abundant calc-alkaline to K-rich gran- (GSI, 1993 itoids along with thin elongated greenstone belt (Harish Kumar et al, 2003). This region evolved during various episodes from 2.7 Ga to 1.1 Ga, the last one being a major kimberlitic event (Anil Kumar et al, 1993). This terrain is extensively intruded by mafic dyke swarms and is unconformably overlain by mid-Proterozoic Cuddapah super group sedimentary sequence.…”

Section: Geologic and Geotectonic Patternmentioning

confidence: 99%

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Unusual lithospheric structure and evolutionary pattern of the cratonic segments of the South Indian shield

Agrawal

Pandey

2014

Earth Planet Sp

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The southern Indian shield, characterised by several prominent geological and geophysical features, can be divided into three distinct tectonic segments: Western Dharwar craton (WDC), Eastern Dharwar craton (EDC) and Southern Granulite terrain (SGT). With the exception of WDC, the entire crust beneath EDC and SGT has been remobilized several times since their formation during the mid-to late Archeans (3.0-2.5 Ga). In order to understand the evolutionary history of these segments, a multiparametric geological and geophysical study has been made which indicates that the south Indian shield, characterized by a reduced heat flow of 23-38 mW/m 2 has a much thinner (88-163 km) lithosphere compared to ∼200-450 km found in other global shields. In the EDC-SGT terrain, high velocity upper crust is underlain by considerably low mantle velocity with a thick high conductive/low velocity zone sandwiched at mid crustal level. Our study reveals that the entire EDC region is underlain by granulite facies rocks with a density of about 2.85 to 3.16 g/cm 3 at a shallow depth of about 8 km in the southern part and at even shallower depth of about 1 to 2 km below the Hyderabad granitic region in the north. Cratonic mantle lithosphere beneath EDC may contain a highly conductive, anisotropic and hydrous metasomatic zone between the depth of 90 and 105 km where estimated temperatures are in the range of 850-975• C. It is likely that before the early Proterozoic, the entire south Indian shield was a coherent crustal block which subsequently got segmented due to persistent plume-induced episodic thermal reactivations during the last 2.7 Ga. These reactivations led to self destruction of cratonic roots giving rise to negative buoyancy at deeper levels which may have been responsible for crustal remobilisations, followed by regional uplifting and erosion of once substantially thick greenstone belts. Consequently, the crustal column beneath the EDC has become highly evolved and now corresponds closely to SGT at depth.

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Section: Discussion Of Results and Conclusionmentioning

confidence: 99%

Section: Geologic and Geotectonic Patternmentioning

confidence: 99%

Unusual lithospheric structure and evolutionary pattern of the cratonic segments of the South Indian shield

Agrawal

Pandey

2014

Earth Planet Sp

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“…Available radiometric ages for the kimberlites of WKF range from 840 to 1150 Ma, whereas those of NKF range from 1080 to 1400 Ma (Anil Kumar et al, 1993;Chalapathi Rao et al, 1996. Chalapathi Rao et al (1999) have suggested that the emplacements of Kotakonda kimberlite in the NKF, and Chelima lamproite in the NLF were contemporaneous ($1400 Ma) and that these pipes are older than the WKF kimberlites ($1090 Ma).…”

Section: Kimberlite Fieldsmentioning

confidence: 99%

Mafic xenoliths in Proterozoic kimberlites from Eastern Dharwar Craton, India: Mineralogy and P–T regime

Patel¹,

Ravi

Anilkumar³

et al. 2009

Journal of Asian Earth Sciences

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“…The first one belong to Lower Vindhyan Group of volcanogenic sediments while the latter three comprising primarily of metasediments represent Upper Vindhyan Group with a major discontinuity at the base of the Kaimur Group. Sarangi et al (2004), Ray et al (2003) and Rasmussen et al (2002) have provided an age of about 1.7-1.6 Ga for Semri Group of rocks while the Upper Vindhyan Groups largely belong to Neoproterozoic (1.0-0.7 Ga, Kumar et al 1993;Ray et al 2003;Ray, 2006). The Mahakoshal and Bijawar Group of rocks (Fig.2a) of Paleoproterozoic (~1.9-1.7 Ga) that largely consist of mafic belonging to Paleo-, Meso-and Neoproterozoic periods, respectively (Fig.2b).…”

Section: Introductionmentioning

confidence: 99%

Long Hiatus in Proterozoic Sedimentation in India: Vindhyan, Cuddapah and Pakhal Basins - A Plate Tectonic Model

Mishra

2011

Journal of the Geological Society of India

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Most of the Proterozoic basins in India, viz. the Vindhyan, the Cuddapah and the Pakhal Basins have experienced long hiatus between the upper and the lower group of rocks. It is proposed that the older group of rocks of Paleoproterozoic period (~1.9-1.6 Ga) formed during the rifting phase caused by large scale magmatism in respective basins possibly due to plume tectonics. On the other hand, the younger group of rocks of Neoproterozoic (~1.0-0.7 Ga) are formed during the final phase of convergence after mountain building that supplied sediments. These geological processes explain large scale disturbances in the older group of rocks during subsequent convergence and collision as they usually occurred along the rifted margins of the cratons. These processes also explain the undisturbed nature, devoid of magmatic rocks of the younger group of rocks and hiatus of about 0.5-0.6 Ga in each case. It is suggested that the plume that was responsible for these rifting of the Indian cratons during Paleo-Mesoproterozoic might have also been responsible for the break up of contemporary Columbian agglomeration in this section. Same model can be used to explain the formation of Proterozoic basins and related hiatus any where else where similar geological environment exist.

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RbSr ages of Proterozoic kimberlites of India: evidence for contemporaneous emplacement

Cited by 140 publications

References 12 publications

Unusual lithospheric structure and evolutionary pattern of the cratonic segments of the South Indian shield

Unusual lithospheric structure and evolutionary pattern of the cratonic segments of the South Indian shield

Mafic xenoliths in Proterozoic kimberlites from Eastern Dharwar Craton, India: Mineralogy and P–T regime

Long Hiatus in Proterozoic Sedimentation in India: Vindhyan, Cuddapah and Pakhal Basins - A Plate Tectonic Model

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