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Development of Ductile Shear Zones during Diapiric Magmatism of Nepheline Syenite and Exhumation of Granulites-Examples from Central Rajasthan, India


Affiliations
1 Department of Geology, Presidency University, Kolkata 700 073, India
2 H. No. 20/75, Mansarovar, Jaipur 302 020, India
3 No. 301, A.R. Complex, I-Block, Sector-14, Hiran Magri, Udaipur 313 001, India
 

The present communication discusses two separate instances where features commonly observed in DSZ are noted, one along the margin of the Kisengarh nepheline syenite and the other in the granulite bodies the Sandmata Complex in Rajasthan, India. The foliations in the nepheline syenite pluton show features similar to the mylonite gneisses that characterize DSZs in orogenic belts. Apart from simulating LS tectonite- type fabric the continuity of similar structures in adjacent cover rocks provides evidence of heterogeneous deformation during upward ascent of nepheline syenite. Based on tectono-metamorphic studies on granulites suggestion is made about the uplift of deepseated granulites accompanied by ductile shearing on along the margins. The development of DSZ along margins helped in reducing the frictional resistance during upward ascent and emplacement into Archaean gneissic terrane. The process is comparable to buoyancy- induced diapiric uplift of hot plutonic bodies through cooler upper crust.

Keywords

Ductile Shear Zone, Diapiric Magmatism, Exhumation of Granulites, Emplacement of Plutonic Bodies.
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  • Development of Ductile Shear Zones during Diapiric Magmatism of Nepheline Syenite and Exhumation of Granulites-Examples from Central Rajasthan, India

Abstract Views: 226  |  PDF Views: 97

Authors

A. B. Roy
Department of Geology, Presidency University, Kolkata 700 073, India
Krishan Dutt
H. No. 20/75, Mansarovar, Jaipur 302 020, India
Sanjeeb Rathore
No. 301, A.R. Complex, I-Block, Sector-14, Hiran Magri, Udaipur 313 001, India

Abstract


The present communication discusses two separate instances where features commonly observed in DSZ are noted, one along the margin of the Kisengarh nepheline syenite and the other in the granulite bodies the Sandmata Complex in Rajasthan, India. The foliations in the nepheline syenite pluton show features similar to the mylonite gneisses that characterize DSZs in orogenic belts. Apart from simulating LS tectonite- type fabric the continuity of similar structures in adjacent cover rocks provides evidence of heterogeneous deformation during upward ascent of nepheline syenite. Based on tectono-metamorphic studies on granulites suggestion is made about the uplift of deepseated granulites accompanied by ductile shearing on along the margins. The development of DSZ along margins helped in reducing the frictional resistance during upward ascent and emplacement into Archaean gneissic terrane. The process is comparable to buoyancy- induced diapiric uplift of hot plutonic bodies through cooler upper crust.

Keywords


Ductile Shear Zone, Diapiric Magmatism, Exhumation of Granulites, Emplacement of Plutonic Bodies.

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DOI: https://doi.org/10.18520/cs%2Fv110%2Fi6%2F1094-1101