Publication Date:
2023-05-22
Description:
A comprehensive analysis of the character, formation, and exhumation of continental crust is studied using seismic reflection profiling across the Achankovil shear zone, Southern Granulite Terrain, India, one of the constituents of the 2000 km long East African orogen. Seismic imaging reveals a dipping reflection fabric extending from the surface to 60 km depth. We interpret the structure developed during the subduction-accretion-suturing of the Madurai and Trivandrum blocks. The deep-seated reflection fabric suggests a rheologically strong lower crust, as viscosity did not change much downwards due to the presence of mafic minerals and granulites in place of quartz and feldspars. Gravity modeling along seismic profile indicated density (velocity) perturbation in the form of high and low intrusive bodies of varying composition in the upper crust. The subduction zone environment might be responsible for the formation of ultramafic rocks comprising dunite, glimmerrite, and spinellite minerals in the region. Charnockites (granulites), the orthopyroxene (hypersthene) bearing anhydrous rocks of granitic composition that are formed at P-T condition between 5-12 Kbars and 700-1040〈sup〉0〈/sup〉 C are exposed on the surface. The ultra-high temperature metamorphic rocks provided insights into crustal dynamics and crust-mantle interaction. Seismic and gravity results are integrated with LVZ at 120 km depth derived from tomographic study, high mantle heat flow data, and various rocks/minerals such as sapphirine, humite bearing marbles, alkaline rocks, arc-related magmatism to understand the structure, composition, and thermal state of the lithosphere.
Language:
English
Type:
info:eu-repo/semantics/conferenceObject
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