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Mineralogy and Petrology

, Volume 112, Issue 4, pp 535–553 | Cite as

Growth of chloritoid and garnet along a nearly isothermal burial path to 70 km depth: an example from the Bughea Metamorphic Complex, Leaota Massif, South Carpathians

  • Elena Negulescu
  • Gavril Săbău
  • Hans-Joachim Massonne
Original Paper

Abstract

Chloritoid-bearing micaschist occurs in the matrix of a subduction mélange (Bughea Complex) of the Leaota Massif (South Carpathians) containing blocks of high-pressure rocks such as eclogite and metagabbronorite. Chloritoid is Mg rich and exclusively enclosed together with chlorite, epidote, paragonite, phengite, quartz, and rutile in mm-sized garnet porphyroblasts embedded in a matrix rich in white mica and chlorite. The Mg content of chloritoid inclusions systematically increases outwards from the inner core of garnet porphyroblasts. Modelling using a pressure (P) — temperature (T) pseudosection predicts the growth of chloritoid together with garnet at the expense of chlorite and other Al-rich phases, while following a nearly isothermal P-T path from 13 kbar and 540 °C to 21 kbar and 560 °C. Breakdown of chloritoid occurred along a P-T path characterised by heating and decompression to 600 °C and 15 kbar. The constrained P-T path is compatible with previously determined ones for eclogites in the Bughea Complex, namely burial in a subduction-accretion complex to depths of 70 km, detachment from the subducting slab, tectonic mixing with blocks sampled from different depths, and, thus, exhumation in a subduction channel.

Keywords

Mg-rich chloritoid Garnet zoning P-T path Pseudosection Micaschist High-pressure metamorphism 

Notes

Acknowledgements

We would like to thank Thomas Theye for the invaluable help provided with the use of the EPMA. Thorough and constructive reviews by Pavel Pitra and Arne Willner, as well as helpful suggestions and directions from the Editor Shah Wali Faryad and Editor-in-Chief Lutz Nasdala are thankfully acknowledged. This contribution was financially supported by Deutscher Akademischer Austauschdienst through grant A/13/03102, and the Romanian Executive Unit for Financing Higher Education, Research, Development and Innovation through grant PN-II-ID-PCE-2011-3-0030.

Supplementary material

710_2017_552_MOESM1_ESM.pdf (890 kb)
Supplementary material 1 (PDF 889 KB)

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Copyright information

© Springer-Verlag GmbH Austria, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Geological Institute of RomaniaBucharest 32Romania
  2. 2.Institut für Mineralogie und Kristallchemie, Universität StuttgartStuttgartGermany

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