Geochronological and geochemical signatures of the granitic rocks emplaced at the north-eastern fringe of the Eastern Dharwar Craton, South India: Implications for late Archean crustal growth

2017 ◽  
Vol 53 (5) ◽  
pp. 1781-1801 ◽  
Author(s):  
Sneha Mukherjee ◽  
Gautam Ghosh ◽  
Kaushik Das ◽  
Sankar Bose ◽  
Yasutaka Hayasaka
Keyword(s):  
South India ◽  
Dharwar Craton ◽  
Granitic Rocks ◽  
Crustal Growth ◽  
Eastern Dharwar Craton ◽  
The North ◽  
North Eastern

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.

Differentiation of Late Archean Crust in the Eastern Dharwar Craton, Krishnagiri-Salem Area, South India

1995 ◽  
Vol 103 (6) ◽  
pp. 629-651 ◽  
Author(s):  
E. C. Hansen ◽  
R. C. Newton ◽  
A. S. Janardhar ◽  
Sheila Lindenberg
Keyword(s):  
South India ◽  
Dharwar Craton ◽  
Eastern Dharwar Craton ◽  
Archean Crust
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