Analysis of deformation fabric in an Alkaline Complex (Koraput): Implications for time relationship between emplacement,fabric development and regional tectonics |
| |
Authors: | Jagatbikas Nanda Saibal Gupta Manish A. Mamtani |
| |
Affiliation: | (1) Department of Geology and Geophysics, Indian Institute of Technology, Kharagpur, 721 302, India |
| |
Abstract: | The Koraput Alkaline Complex (KAC) lies on the NE-SW trending Sileru Shear Zone (SSZ) separating the Proterozoic Eastern Ghats Province from the Archaean Indian craton. The core of the KAC is made of hornblende gabbro, which is rimmed by a band of nepheline syenite in the east and syenodiorite in the west. The timing of magmatism with respect to the SSZ is disputed. The KAC was deformed during emplacement, and a magmatic foliation related to the syn-emplacement deformation, D 1 , is present in the gabbroic core. The dominant D 2 -related field fabric strikes NESW and is penetrative in parts of the gabbro and marginal lithologies. E-W trending D 3 shear zones cut across the complex. Distinct textural domains resulted from strain partitioning during deformation. Parts of the complex with magmatic textures constitute Domain-1, while D 2 and D 3 fabric zones comprise Domains-2 and 3 respectively. Temperatures in the KAC initially decreased following D 1 , but increased through D 2 and D 3 . Anisotropy of magnetic susceptibility (AMS) studies show that the magnetic fabric generally follows S 1 in Domain-1. While the magnetic fabric in Domain-2 is dominantly parallel to S 2 , some of it parallels S 1 . The latter is a relict D 1 fabric that is recognized from AMS analysis but is obliterated in the field, which confirms that the KAC pre-dates the SSZ. The response of magnetic fabrics to temperature and implications of the study for Indo-Antarctica amalgamation are discussed. |
| |
Keywords: | Anisotropy of magnetic susceptibility Alkaline complex Fabric Eastern Ghats Belt Indo-Antarctica amalgamation |
本文献已被 SpringerLink 等数据库收录! |
|