Evolution of the Continental Crust in the Proterozoic Eastern Ghats Belt, India and new constraints for Rodinia reconstruction: implications from Sm-Nd, Rb-Sr and Pb-Pb isotopes

• Published in: Precambrian Research
• Main Authors: Rickers, K., Mezger, K., Raith, M.
• Other Authors: 3.3 Chemistry and Physics of Earth Materials, 3.0 Geodynamics and Geomaterials, Departments, GFZ Publication Database, Deutsches GeoForschungsZentrum
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: 2001
• Subjects: 550 - Earth sciences; Antarctic; Antarc*
• Online Access: https://gfzpublic.gfz-potsdam.de/pubman/item/item_228644

For this study Nd, Sr and Pb isotope compositions were analyzed for ortho- and paragneisses from the Eastern Ghats Belt of India in order to determine its crust formation and crustal evolution. This belt represents a Proterozoic orogen that extends along the east coast of Peninsular India and forms part of the mobile belts in East Gondwana and Rodinia. The Eastern Ghats Belt was affected by Mesoproterozoic granulite facies metamorphism in the western segment (Western Charnockite Zone) and a Grenvillian regional-scale high-grade event in the central and eastern segments (Western Khondalite Zone, Charnockite Migmatite Zone and Eastern Khondalite Zone) as well as a local Pan-African overprint. The results of the isotope studies are used for the large-scale reconstruction of the indo-antarctic part of the Rodinia supercontinent. Based on Nd model ages and Pb isotope ratios from leached feldspars four crustal domains can be distinguished in the Eastern Ghats Belt. These domains can in part be correlated with the lithological division of the belt: (1) The Western Charnockite Zone south of the Godavari Graben is characterized by Nd model ages between 2.3 and 2.5 Ga for orthogneisses and 2.6 and 2.8 Ga for metasediments (Domain 1). The Pb isotopes are primitive indicating reworking of dominantly Archean and mixing with minor Proterozoic material; (2) North of Godavari Graben Nd model ages for orthogneisses are significantly higher with values ranging from 3.2 to 3.9 Ga. The Pb isotopes are strongly retarded; (3) The north-eastern parts of the Charnockite Migmatite Zone and Western Khondalite Zone form a distinct and almost homogeneous crustal domain (Domain 3) with Nd model ages between 1.8 and 2.2 Ga; (4) Between the isotopically homogeneous terranes stretches a broad transition zone (Domain 2) enclosing parts of the Western Khondalite Zone, Charnockite Migmatite Zone and Eastern Khondalite Zone. The Nd model ages for metasediments (2.1–2.5 Ga) are younger than paragneiss ages of the adjoining Western Charnockite Zone. ...