Sapphirine-Bearing Quartzite from the Eastern Ghats Granulite Terrain, Vizianagaram, India

Kamineni, D. C.; Rao, A. T.

doi:10.1086/629210

Cited by 47 publications

(30 citation statements)

References 33 publications

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“…P-T conditions of 8 -12 kbar and 1000 -1100°C have been calculated for these assemblages [Lal et al, 1987;Kamineni and Rao, 1988;Sengupta et al, 1990;Bhowmik et al, 1995;Sen et al, 1995;Shaw and Arima, 1996;Mohan et al, 1997;Rickers et al, 2001]. The P-T -path follows an anticlockwise trajectory with a high initial dT/dP slope as depicted in Figure 2 [Kondapalli and Anantgiri area, Sengupta et al, 1990;Dasgupta, 1995;Mukhopadhyay and Bhattacharya, 1997].…”

Section: Metamorphismmentioning

confidence: 99%

Timing and dynamics of the juxtaposition of the Eastern Ghats Mobile Belt against the Bhandara Craton, India: A structural and zircon U‐Pb SHRIMP study of the fold‐thrust belt and associated nepheline syenite plutons

2007

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Sensitive High Resolution Ion MicroProbe (SHRIMP) U‐Pb dating of zircon from basement granite gneisses and nepheline syenites of the Sinapalli Nappe, occurring along the northwestern margin of the Eastern Ghats Mobile Belt, indicate high grade regional metamorphism and associated folding accompanying juxtaposition of the nappe with the Bhandara Craton, to have taken place between 617 ± 85 Ma (lower intercept age of a reworked basement unit) and 517 Ma (age of the youngest syenite). This shows, for the first time, that the final juxtaposition of the northwestern parts of the Eastern Ghats Mobile Belt against the Bhandara Craton came about in the late Neoproterozoic and not, as previously thought, during the Mesoproterozoic. The northwestern part of the Eastern Ghats Mobile Belt comprises a fold‐ thrust belt consisting of a stack of northwesterly verging nappes that have been thrust over the Bhandara Craton. The Sinapalli Nappe is the lowermost nappe and rests over a tectonic contact on the Archean granites and gneisses of the craton. The basal décollement is exposed as a two‐km‐wide ductile‐brittle thrust, hosting nepheline syenite plutons that show fabrics consistent with a synkinematic emplacement during thrusting. The Sinapalli Nappe is comprised of a sequence of alternating mafic granulites and quartzofeldspathic gneisses with slivers of basement granites, which are folded in three phases of folding (F1, F2 and F3) and were subjected to granulite facies metamorphism during F1 folding. Thrusting is synkinematic to F2 folding and is responsible for the juxtaposition of the northwestern part of the Eastern Ghats Terrane over the Bhandara Craton during the assembly of parts of eastern Gondwana.

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Section: Metamorphismmentioning

confidence: 99%

Timing and dynamics of the juxtaposition of the Eastern Ghats Mobile Belt against the Bhandara Craton, India: A structural and zircon U‐Pb SHRIMP study of the fold‐thrust belt and associated nepheline syenite plutons

2007

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“…North of the Godavari Rift also an early UHT (~1000°C) metamorphic event (M 1 ) at crustal depths of 30-35km (8-10 kb) is reported from high-Mg-Al granulites in several areas (Fig.6), like Anantagiri (Sengupta et al 1990), Anakapalle (Dasgupta et al 1994;Rickers et al 2001b;Sanyal and Fukuoka, 1995), Araku , Paderu (Bhattacharya and Kar, 2002;Lal et al 1987;Pal and Bose, 1997), Rayagada (Shaw and Arima, 1996a, 1996b, 1998, G. Madugula (Mohan et al 1997), Vizianagram (Kamineni and Rao, 1988a), Sunkarametta (Bose et al 2000), Rajamundry , Kakanuru (Kamineni and Rao, 1988b), Deobhog Neogi and Das, 2000), from calc-granulites of Borra (Bhowmik et al 1995), Garividi and Rajamundry (Dasgupta et al 1992;Dasgupta, 1993), Anakapalle (Sengupta et al 1997a) and also from mafic granulites from Araku-Anantagiri areas Dasgupta et al 1993).…”

Section: Eastern Ghats Provincementioning

confidence: 98%

“…The retrograde path of M 2 is characterized by near isothermal decompression to ~5 kb as constrained by thermobarometric data. The formation of second generation of cordierite in pelitic gneisses at the expense of orthopyroxene+sillimanite+garnet+quartz, and of decomposition of garnet to plagioclase+ orthopyroxene/ ilmenite/biotite is generally attributed to this decompression (Dasgupta et al 1992(Dasgupta et al , 1994Kamineni and Rao, 1988a;Mohan et al 1997;Mukhopadhyay and Bhattacharya, 1997;Sengupta et al 1990). However, Das et al (2008) argued that in the mafic granulites from the western boundary shear zones the reactant phases for the production of orthopyroxene+ plagioclase symplectites are hornblende, plagioclase and garnet, and the symplectites are formed due to post-thrust reheating rather than decompression.…”

Section: Eastern Ghats Provincementioning

confidence: 99%

The Eastern Ghats Belt … A polycyclic granulite terrain

Mukhopadhyay

Basak

2009

J Geol Soc India

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The Eastern Ghats Belt is a polycyclic granulite terrain along the east coast of India whose western boundary is marked by a shear zone along which the granulites are thrusted over the cratonic units of the Indian shield, and its northern margin is marked by the presence of a number of fault-bounded blocks. Recent work has convincingly brought out that there are domains within the belt having different evolutionary histories. The segment south of the Godavari Rift went through a high grade thermo-tectonic event at ~1.6-1.7 Ga. North of the Godavari Rift in a narrow zone along the western boundary the last high-grade metamorphic event is of late Archaean age. A series of alkaline plutons along the western boundary zone testifies to a rifting episode at ~1.3-1.5 Ga. In the major part of the EGB the metamorphism is broadly of Grenvillian age, with two major thermo-tectonic pulses at ~1.1-1.2 Ga and ~0.95-1.0 Ga. But high grade conditions persisted for a long period and younger thermal events of ~0.65 Ga to ~0.80 Ga are locally recorded. There are differences in the tectonometamorphic histories of different domains, but the tectonic significance of these differences remains uncertain. Pan-African (0.50-0.55) thermal overprints are common and become conspicuous along the western boundary zone. The thrusting of the Eastern Ghats granulites in a hot state over the cratons to the west is of Pan-African age. In the Rodinia assembly (~0.9 Ga) the Eastern Ghats and the Rayner-Napier Complexes of Antarctica were contiguous, but the pre-Rodinia configuration of these terrains remains unclear. At ~0.8 Ga during the Rodinia break up Greater India rifted apart from East Antarctica, and only later it docked with Australia-East Antarctica at 530-550 Ma. The continuation of the East Antarctic Pan-African orogenic belts into the Eastern Ghats is yet to be ascertained.

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“…The Vizianagaram area in the northern part of the Eastern Ghats Belt (henceforth EGB), exposes an ensemble of repeatedly deformed and metamorphosed granulite to amphibolite facies rocks of diverse bulk compositions (Kanungo & Murthy, 1981; Kamineni & Rao, 1988; Grew et al ., 2001; Datta et al ., 2001). Khondalite (garnet + sillimanite + quartz + alkali feldspar ± plagioclase ± graphite) is the dominant rock of this area, containing tectonically detached lenses of felsic, mafic and calc‐silicate rocks of various dimensions.…”

Section: Background Geologymentioning

confidence: 99%

Stability of fluorite and titanite in a calc‐silicate rock from the Vizianagaram area, Eastern Ghats Belt, India

Sengupta

Raith

Datta

2004

Journal Metamorphic Geology

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In the Vizianagaram area (E 83°29.442¢; N 18°5.418¢) of the Eastern Ghats Belt, India, a suite of graphite-bearing calc-silicate granulites, veined by syenitic rocks, developed wollastonite-rich veins at 6-7 kbar and > 850°C. During subsequent near-isobaric cooling wollastonite was replaced by calcite + quartz and a graphic intergrowth of fluorite + quartz ± clinopyroxene. Titanite with variable Al and F contents is present throughout the rock. Combining the compositional variation of titanite and recent experimental data, it is demonstrated that the mineral assemblage, the composition of coexisting fluids and the mobility of Al exert a far greater control on the composition of titanite than pressure, temperature or the whole rock composition. Thermodynamically computed isothermalisobaric logf O 2 -logf CO 2 and logf F 2 -logf O 2 grids in the systems Ca-Fe-Si-O-F (CISOF; calcite-free) and Ca-Fe-Si-O-F-C-H (CISOFV; calcite-present) demonstrate the influence of bulk rock and fluid compositions on the stability of the fluorite-bearing assemblages in diverse geological environments and resolve the problem of the stability of titanite in fayalite + fluorite-bearing rocks in the Adirondacks. The mineralogy of the studied rocks and the topological constraints tightly fix the logf O 2 , logf F 2 and logf CO 2 at )15.8, )30.6 and 4.1, respectively, at 6.5 kbar and c. 730°C. Because of the similarity in the P-T conditions, the compositions of pore fluids in the fluorite-bearing assemblages of the Adirondacks and the Eastern Ghats Belt have been compared.

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Sapphirine-Bearing Quartzite from the Eastern Ghats Granulite Terrain, Vizianagaram, India

Cited by 47 publications

References 33 publications

Timing and dynamics of the juxtaposition of the Eastern Ghats Mobile Belt against the Bhandara Craton, India: A structural and zircon U‐Pb SHRIMP study of the fold‐thrust belt and associated nepheline syenite plutons

Timing and dynamics of the juxtaposition of the Eastern Ghats Mobile Belt against the Bhandara Craton, India: A structural and zircon U‐Pb SHRIMP study of the fold‐thrust belt and associated nepheline syenite plutons

The Eastern Ghats Belt … A polycyclic granulite terrain

Stability of fluorite and titanite in a calc‐silicate rock from the Vizianagaram area, Eastern Ghats Belt, India

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