Progressive Metamorphism of Mafic Rocks from Greenschist to Granulite Facies in the Dharwar Craton of South India

1986 ◽  
Vol 94 (2) ◽  
pp. 261-282 ◽  
Author(s):  
P. Raase ◽  
M. Raith ◽  
D. Ackermand ◽  
R. K. Lal
Keyword(s):  
South India ◽  
Granulite Facies ◽  
Dharwar Craton ◽  
Mafic Rocks

Zircon ages and the distribution of Archaean and Proterozoic rocks in the Rauer Islands

1993 ◽  
Vol 5 (2) ◽  
pp. 193-206 ◽  
Author(s):  
P. D. Kinny ◽  
L. P. Black ◽  
J. W. Sheraton
Keyword(s):  
Granulite Facies ◽  
Metamorphic Rocks ◽  
Low Grade ◽  
High Grade ◽  
Ion Microprobe ◽  
Rock Interaction ◽  
Mafic Rocks ◽  
Grade Fluid ◽  
Vestfold Hills ◽  
Intrusive Suite

The application of zircon U-Pb geochronology using the SHRIMP ion microprobe to the Precambrian high-grade metamorphic rocks of the Rauer Islands on the Prydz Bay coast of East Antarctica, has resulted in major revisions to the interpreted geological history. Large tracts of granitic orthogneisses, previously considered to be mostly Proterozoic in age, are shown here to be Archaean, with crystallization ages of 3270 Ma and 2800 Ma. These rocks and associated granulite-facies mafic rocks and paragneisses account for up to 50% of exposures in the Rauer Islands. Unlike the 2500 Ma rocks in the nearby Vestfold Hills which were cratonized soon after formation, the Rauer Islands rocks were reworked at about 1000 Ma under granulite to amphibolite facies conditions, and mixed with newly generated felsic crust. Dating of components of this felsic intrusive suite indicates that this Proterozoic reworking was accomplished in about 30–40 million years. Low-grade retrogression at 500 Ma was accompanied by brittle shearing, pegmatite injection, partial resetting of U-Pb geochronometers and growth of new zircons. Minor underformed lamprophyre dykes intruded Hop and nearby islands later in the Phanerozoic. Thus, the geology of the Rauer Islands reflects reworking and juxtaposition of unrelated rocks in a Proterozoic orogenic belt, and illustrates the important influence of relatively low-grade fluid-rock interaction on zircon U-Pb systematics in high-grade terranes.

scholarly journals Close-range geological photogrammetry studies: field and laboratory procedures with examples from prograde granulite facies orthogneisses, Kerala, South India

1992 ◽  
Vol 156 ◽  
pp. 53-62
Author(s):  
A.A Garde
Keyword(s):  
South India ◽  
Granulite Facies ◽  
Ground Control ◽  
Practical Procedure ◽  
Small Frame ◽  
Palghat Gap ◽  
Close Range ◽  
On Line ◽  
Laboratory Procedures ◽  
Metamorphic Facies

Precambrian orthogneisses exposed in quarries in the Palghat Gap, KeraIa, South India, were photographed for use in geological photogrammetry studies with a 35 mm (small frame) hand-held camera. Local ground control was provided by simple means: hand level, geological compass and 2 m rule. The practical procedure of photography and acquisition of ground control data is described. The stereoscopic photographs, which show complicated field relations in gneisses with prograde, transitional amphibolite to granulite metamorphic facies relations, were studied using multi-model photogrammetry (see Dueholm, 1992) and an analytical plotter. The estimated standard deviations in the stereo models of scale, azimuth and levelling were ± 2%, 2° and 5°, respectively, but the precision was very good (Iess than 1 cm). Outcrop maps were drawn with an on-line plotter at scales varying from 1:25 to 1:200 with contour intervals between 5 and 100 cm. The plot data were transferred, edited on a Macintosh computer and made ready for publication with a vector-based graphics application.

Archaean stromatolites from the Chitradurga schist belt, Dharwar Craton, South India

1989 ◽  
Vol 43 (3) ◽  
pp. 239-250 ◽  
Author(s):  
R. Srinivasan ◽  
Manoj Shukla ◽  
S.M. Naqvi ◽  
V.K. Yadav ◽  
B.S. Venkatachala ◽  
...  
Keyword(s):  
South India ◽  
Dharwar Craton ◽  
Schist Belt

scholarly journals Magnetotelluric investigation of lithospheric electrical structure beneath the Dharwar Craton in south India: Evidence for mantle suture and plume-continental interaction

2019 ◽  
Vol 10 (5) ◽  
pp. 1915-1930 ◽  
Author(s):  
D. Malleswari ◽  
K. Veeraswamy ◽  
K.K. Abdul Azeez ◽  
A.K. Gupta ◽  
Narendra Babu ◽  
...  
Keyword(s):  
South India ◽  
Dharwar Craton ◽  
Electrical Structure

Deformation-driven emplacement-differentiation in the Closepet pluton, Dharwar Craton, South India: an alternate view

2019 ◽  
Vol 489 (1) ◽  
pp. 261-274 ◽  
Author(s):  
Abhijit Bhattacharya
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
South India ◽  
Major Element ◽  
Volume Fraction ◽  
Dharwar Craton ◽  
The North ◽  
Magmatic Fabric ◽  
Melt Composition ◽  
Crystal Content

AbstractIn the Late Archean north-trending Closepet pluton, trains of euhedral K-feldspar phenocrysts and matrix-supported idiomorphic K-feldspar crystals in the central part of the pluton define oblique-to-pluton margin steep-dipping east/ENE-trending magmatic fabrics. The magmatic fabric is defined by phenocryst-rich and phenocryst-poor layers, with the euhedral porphyries continuous across the layers. The fabrics are near-orthogonal to the gently-dipping gneissic layers in the host gneisses. The fabrics curve adjacent to locally-developed north/NNE-trending melt-hosted dislocations parallel to the axial planes of horizontal/gently-plunging north-trending upright folds in the host gneisses. In the pluton interior, both fabrics in the intrusives formed at supra-solidus conditions, although the volume fraction of melts diminished drastically due to cooling/melt expulsion. At the pluton margin, the north-trending fabric is penetrative and post-dates magma solidification. Within the pluton, the major element oxides, rare earth elements, anorthite contents in plagioclase, and (Mg/Fe + Mg) ratios in biotite decrease with increasing SiO2 from phenocryst-rich (up to 75% by volume) granodiorite to phenocryst-poor (<15 vol%) granite that broadly correspond to minimum melt composition. The chemical-mineralogical variations in the pluton is attributed to deformation-driven ascent of magma with heterogeneous crystal content, ascending at variable velocities (highest in crystal-poor magma) along oblique-to-pluton margin east/ENE-trending extensional fractures induced by dextral shearing.

scholarly journals SHRIMP U–Pb zircon ages of granitoids adjacent to Chitradurga shear zone, Dharwar craton, South India and its tectonic implications

2015 ◽  
Vol 110 (5) ◽  
pp. 224-234 ◽  
Author(s):  
Abdulla NASHEETH ◽  
Takamoto OKUDAIRA ◽  
Kenji HORIE ◽  
Tomokazu HOKADA ◽  
Madhusoodhan SATISH–KUMAR
Keyword(s):  
Shear Zone ◽  
South India ◽  
Dharwar Craton ◽  
Tectonic Implications

Metamorphic evolution of the Karimnagar granulite terrane, Eastern Dharwar Craton, south India

2010 ◽  
Vol 148 (1) ◽  
pp. 112-132 ◽  
Author(s):  
D. PRAKASH ◽  
I. N. SHARMA
Keyword(s):  
Granulite Facies ◽  
Dharwar Craton ◽  
Ultramafic Rocks ◽  
Chemical Compositions ◽  
Eastern Dharwar Craton ◽  
Geochronological Data ◽  
Rock Types ◽  
Wide Range ◽  
The Subject ◽  
Lower Crustal

AbstractThe Karimnagar granulite terrane is an integral part of the Eastern Dharwar Craton (EDC), India, having been the subject of much interest because of the only reported granulite facies rocks in the EDC. It shows a large variety of rock types with a wide range of mineral parageneses and chemical compositions, namely charnockites (Opx+Pl+perthite+Qtz±Bt±Grt), gneisses (Opx+Crd+Bt+Pl+Qtz+perthite±Sil±Grt±Spl; Bt+Qtz+Pl±Crd±Hbl±Spl), mafic granulites (Cpx+Pl+Qtz±Opx±Hbl), quartz-free granulites (Spr+Spl+Bt+Crd+Kfs+Crn; Bt+Crd+Kfs±Crn±Spl±Krn; And+Bt+Kfs+Chl), granites (Qtz+Pl+Kfs±Bt±Hbl), altered ultramafic rocks (Chl+Trem+Tlc), metadolerites (Cpx+Pl±Bt±Qtz±Chl), banded magnetite quartzites and quartzites. Andalusite- and chlorite-bearing assemblages presumably suggest a retrograde origin. Investigation of quartz-free granulites of the area brings out some interesting and important observations, reflecting the presence of refractory phases. These granulites are devoid of sillimanite and contain corundum instead. Reaction textures in the gneisses include breakdown of garnet to form coronas and symplectites of orthopyroxene+cordierite, formation of cordierite from garnet+sillimanite+quartz and late retrograde biotite and biotite+quartz symplectites. In the mafic granulites, inclusions of quartz and hornblende within orthopyroxene are interpreted as being a part of the prograde assemblage. At a later stage orthopyroxene is also rimmed by hornblende. The quartz-free granulites display a variety of spectacular coronas, for example, successive rims on corundum consisting of spinel+sapphirine+cordierite±orthopyroxene, rare skeletal symplectitic intergrowth of sapphirine+cordierite+potash feldspar, and late retrograde formation of chlorite, corundum, spinel and andalusite from sapphirine±cordierite. Based on chemographic relationships and petrogenetic grids, a sequence of prograde, isothermal decompressive and retrograde reactions have been inferred. Quartz-free sapphirine granulites and mafic granulites record the highest P–T conditions (~7 kbar, 850°C), whereas the gneisses were formed at lower P–T conditions (~5 kbar, 800°C). In addition, the presence of andalusite-bearing rocks suggests a pressure of around 2.5 kbar. This change in pressure from 7 kbar to around 2.5 kbar suggests a decompressive path for the evolution of granulites in the study area, which indicates an uplift for the granulite-facies rocks from lower crustal conditions. The implications for supercontinent history are also addressed in light of available geochronological data.

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