Skip Navigation



Journal of Petrology Advance Access published online on November 30, 2007
Journal of Petrology, doi:10.1093/petrology/egm072
This Article
Right arrow Full Text Freely available
Right arrow FREE Full Text (PDF) Freely available
Right arrow Supplementary Data
Right arrow All Versions of this Article:
49/1/107    most recent
egm072v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrowRequest Permissions
Google Scholar
Right arrow Articles by Saha, L.
Right arrow Articles by Dasgupta, S.
Right arrow Search for Related Content
GeoRef
Right arrow GeoRef Citation
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

© The Author 2007. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oxfordjournals.org

Contrasting Episodes of Regional Granulite-Facies Metamorphism in Enclaves and Host Gneisses from the Aravalli–Delhi Mobile Belt, NW India

L. Saha1, S. K. Bhowmik1,*, M. Fukuoka2 and S. Dasgupta3

1Department of Geology and Geophysics, Indian Institute of Technology, Kharagpur-721 302, India 2Department of Earth and Planetary Sciences, Hiroshima University, Higashi-Hiroshima, Japan and 3Indian Institute of Science Education and Research, Hc Block, Sector Iii, Salt Lake, Kolkata-700 106, India

Received September 20, 2006; Revised typescript accepted October 16, 2007


  Abstract

The Aravalli–Delhi Mobile Belt in the northwestern part of India demonstrates how granulite enclaves and their host gneisses can be utilized to unravel multistage metamorphic histories of orogenic belts, using three suites of metamorphic rocks: (1) an enclave of pelitic migmatite gneiss–leptynite gneiss; (2) metamorphosed megacrystic granitoids, intrusive into the enclave; (3) host tonalite–trondhjemite–granodiorite (TTG) gneisses associated with an interlayered sequence of garnetiferous metabasite and psammo-pelitic schist, locally migmatitic. Based on integrated structural, petrographic, mineral compositional, geothermobarometric studies and P–T pseudosection modelling in the systems NCKFMASH and NCFMASH, we record three distinct tectonothermal events: an older, medium-pressure granulite-facies metamorphic event (M1) in the sillimanite stability field, which is registered only in the enclave, a younger, kyanite-grade high-pressure granulite-facies event (M2), common to all the three litho-associations, and a terminal amphibolite-facies metamorphic overprint (M3). The high-P granulite facies event has a clockwise P–T loop with a well-constrained prograde, peak (M2, P ~12–15 kbar, T ~815°C) and retrograde (M2R, ~6·1 kbar, T ~625°C) metamorphic history. M3 is recorded particularly in late shear zones. When collated with available geochronological data, the metamorphic P–T conditions provide the first constraint of crustal thickening in this belt, leading to the amalgamation of two crustal blocks during a collisional orogeny of possible Early Mesoproterozoic age. M3 reactivation is inferred to be of Grenvillian age.

KEY WORDS: Northwestern India; polycyclic granulite enclave; pseudosection; high-pressure metamorphism; P–T path

*Corresponding author. E-mail: santanu{at}gg.iikgp.ernet.in


Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?




Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.