Metamorphic petrology

 

Partial melting of high-grade pelites and processes of melt extraction

Experimental and field based research into the processes by which granites are generated in the crust. This includes experimental work looking at fluid-absent biotite-melting reactions (with Prof. J.D. Clemens, now at Kingston, and G. Stevens, now at Stellenbosch) and a complementary field-based study of partial melting of pelites in the vicinity of the Huntly Gabbro, NE Scotland (with Prof. Clemens and student D.J. Dalrymple). How such granitic melts are physically extracted from their source rocks is currently a topic exciting much interest; aspects of this complex problem are being studied by a combined experimental and field approach in collaboration with Prof. E.H. Rutter, Dr. K.H. Brodie and Dr. D. Irving.

  • Stevens, G., Clemens, J. D. & Droop, G. T. R. 1997. Melt production during granulite-facies anatexis: experimental data from "primitive" metasedimentary protoliths. Contributions to Mineralogy and Petrology 128, 352-370.
  • Droop, G. T. R., Clemens, J. D. & Dalrymple, D. J. 2003. Processes and conditions during contact anatexis, melt escape and restite formation: The Huntly Gabbro complex, NE Scotland. Journal-of-Petrology 44(6), 995-1029.

For more information contact: Giles Droop

 

Application of 40Ar/ 39Ar Laser Probe Dating to the Interpretation of Metamorphic Rocks

This project makes use of the state-of-the-art 40Ar/ 39Ar laser-probe dating facility to time-calibrate P-T paths. The project aims to provide a detailed history of metamorphism and deformation, and ultimately provide data on the dynamics of orogenic processes. This project is conducted by Chris Horsfall in collaboration with Ray Burgess of the Isotope Group.

For more information contact: Chris Horsfall or Giles Droop

 

Variations in water activity in thermal aureoles and regional metamorphic terranes

In this project (started in collaboration with student M. Moazzen), water contents (determined by secondary ion mass spectrometry) of cordierites that crystallised at known P and T are used as sensors of water activity. In the Etive aureole, W Scotland, an abrupt transition in the magnitude of water activity has been found within migmatised pelites of the melt-present zone, which has implications for the contrasting role of fluid during partial melting at different locations within the inner aureole. Building on this, work is under way (with Dr. C. Hayward and student M. Rigby) to develop an electron-microprobe technique for quantifying the H 2O and CO 2 contents of cordierites using the state-of-the-art Cameca SX-100 probe at Manchester. The intention is to apply this technique to estimate H 2O and CO 2 activity variations across a variety of medium- and high-grade regional and contact metamorphic terranes with a view to assessing the role of fluid in metamorphism and melting.

  • Moazzen, M., Droop, G. T. R. & Harte, B. 2001. Abrupt transition in H 2O activity in the melt-present zone of a thermal aureole: Evidence from H 2O contents of cordierites. Geology 29(4), 311-314.

For more information contact: Giles Droop

 

'Alpine' subduction complexes of the Middle East

Ongoing collaborative projects with Dr. M. Celik (at Konya), visiting student G. Fotoohi Rad (from Teheran) and Dr. R. Burgess (at Manchester) are examining the metamorphic P-T evolution of blueschist- and eclogite-facies rocks in central Turkey and eastern Iran, respectively. The results should shed light on the tectonic evolution of hitherto poorly known segments of the `Alpine-Himalayan' chain.

For more information contact: Giles Droop

 

Examining the role of orogenic spreading in the Scottish Dalradian

The interplay between deformation and metamorphism in the Grampian orogenic belt in the Scottish Highlands is being examined by applying new thermodynamic computational techniques to garnets with preserved compositional growth-zoning, in Dalradian rocks of known structural context. The idea is to see whether or not these garnets, which can be shown on textural grounds to have grown during the `D2' regional deformation episode (considered by some workers to reflect vertical shortening), did indeed grow during a period of decompression. This work is at a very preliminary stage. The results should help clarify the relative roles of tectonic thickening and gravitational spreading in the early to middle part of the tectonothermal evolution of the Grampian orogenic belt.

For more information contact: Giles Droop

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