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Contributions to Mineralogy and Petrology

, Volume 129, Issue 2–3, pp 182–197 | Cite as

Mid-crustal contact metamorphism around the Chimakurthy mafic-ultramafic complex, Eastern Ghats Belt, India

  • Somnath Dasgupta
  • Jürgen Ehl
  • Michael M. Raith
  • Pulak Sengupta
  • Pranesh Sengupta
Article

Abstract

Pelitic rocks were thermally metamorphosed at the contact of the Chimakurthy mafic-ultramafic igneous complex, Eastern Ghats Belt, India. The rocks show progressive change in mineralogy from biotite-sillimanite-quartz-garnet-K-feldspar (association I, 150 m from the intrusive contact) to garnet-spinel-cordierite-K-feldspar-sillimanite (association II, 20–30 m from the intrusive contact) to cordierite-K-feldspar-(cordierite-orthopyroxene-K-feldspar symplectite after osumilite)-spinel-FeTiAl oxides with/without garnet (associations III and IV, 5 m from the intrusive contact), and finally to spinel-orthopyroxene-cordierite-K-feldspar (association V, xenoliths). Oxide mineral clots in associations III and IV resemble emery-type rocks. Initial mineral reactions involved biotite-dehydration melting with partial segregation of the melt. Down-temperature mineral reactions were largely diffusion controlled and preservation of symplectitic and coronitic textures in microdomains is common. Interpretation of reaction textures in relevant petrogenetic grids for the sytems KFMASH and FMAS and combined with geothermobarometry suggest that the pelitic rocks were thermally metamorphosed at c. 6 kbar pressure along a heating-cooling trajectory within the temperature interval between c. 750 °C and c. 1000 °C.

Keywords

Temperature Interval Mineral Reaction Oxide Mineral Progressive Change Igneous Complex 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag Berlin Heidelberg 1997

Authors and Affiliations

  • Somnath Dasgupta
    • 1
  • Jürgen Ehl
    • 2
  • Michael M. Raith
    • 2
  • Pulak Sengupta
    • 1
  • Pranesh Sengupta
    • 1
  1. 1.Department of Geological Sciences, Jadavpur University, Calcutta-700 032, IndiaIN
  2. 2.Mineralogisch-Petrologisches Institut der Universität Bonn, Poppelsdorfer Schloss, D-53115 Bonn, GermanyDE

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