The Mozambique Ocean Suture in Southern India: Age and Significance of Granulites in the Palghat-Cauvery Shear Zone System

Abstract

The Neoproterozoic oceans that closed as Gondwana amalgamated left a cryptic, yet recognisable, record in the resulting orogens. These consist of Neoproterozoic oceanic or ocean-margin protoliths, relatively high-pressure metamorphic belts separating distinct crustal domains, and Neoproterozoic provenance fronts. The southern Indian Palghat-Cauvery shear zone system, is interpreted as the remains of the Neoproterozoic Mozambique Ocean, because: a) it separates Archaean and Palaeoproterozoic granulites from the extensive Neoproterozoic-Cambrian Southern Granulite Domain; b) it contains mafic gneisses that may have formed within a Neoproterozoic Ocean; c) it preserves distinctive high pressure, ultra-high temperature granulites that were metamorphosed in the Cambrian Malagasy Orogeny, and; d) it isolates southern Indian Proterozoic metasediments that are unlikely to be sourced from north of the shear system.