Journal of Petrology Advance Access published online on October 1, 2004
Journal of Petrology, doi:10.1093/petrology/egh071
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
1 DEPARTMENT OF GEOLOGY, UNIVERSITY OF GEORGIA, ATHENS, GA 30602, USA
* To whom correspondence should be addressed. E-mail: klingon{at}3rdrock.gly.uga.edu.
The behavior of igneous continental crust during subduction is modeled by means of vapor-absent partial melting experiments on a tonalite, containing equal amounts of biotite and hornblende, at pressures of 15-32 kbar. The experiments produce leucogranitic melts coexisting with garnet + omphacitic clinopyroxene + K-feldspar + kyanite + quartz/coesite ± phengite ± zoisite. Experimental constraints and geometrical analysis of phase equilibria show that the hydrous phases that control dehydration-melting of tonalites in deep thickened continental crust and in the upper mantle are phengite and zoisite. The negatively sloping amphibole + quartz vapor-absent solidus characteristic of amphibolites is largely suppressed in tonalites, because amphibole is eliminated by water-conserving reactions that also consume K-feldspar and kyanite and produce phengite and zoisite. The temperature at which melt first appears in the experiments varies from <900°C at 15 kbar, to 1000°C at 27 kbar, to <925°C at 32 kbar. Moderate degrees of partial melting (20-30%) yield residual assemblages with mantle-like densities but which can still contain minor amounts of hydrous phases. Partial melting of tonalitic crust during continental subduction can thus generate incompatible element-rich residues that would be able to remain in the mantle indefinitely, acting as long-term sources of metasomatic fluids.
Accepted August 6, 2004
Article
Vapor-Absent Melting of Tonalite at 15-32 kbar
Abstract 
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  H. K. Brueckner Subduction of continental crust, the origin of post-orogenic granitoids (and anorthosites?) and the evolution of Fennoscandia Journal of the Geological Society, July 1, 2009; 166(4): 753 - 762. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. J. Gregory, I. S. Buick, J. Hermann, and D. Rubatto Mineral-scale Trace Element and U-Th-Pb Age Constraints on Metamorphism and Melting during the Petermann Orogeny (Central Australia) J. Petrology, February 3, 2009; (2009) egn077v1. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. B. Thomsen and M. W. Schmidt The Biotite to Phengite Reaction and Mica-dominated Melting in Fluid + Carbonate-saturated Pelites at High Pressures J. Petrology, October 29, 2008; (2008) egn051v1. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Hermann and C. J. Spandler Sediment Melts at Sub-arc Depths: an Experimental Study J. Petrology, April 1, 2008; 49(4): 717 - 740. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. D. Putirka Thermometers and Barometers for Volcanic Systems Reviews in Mineralogy and Geochemistry, January 1, 2008; 69(1): 61 - 120. [Full Text] [PDF]
|
|
|
|
 |
|
 Y. Hiroi, Y. Motoyoshi, N. Ishikawa, T. Hokada, and K. Shiraishi Origin of xenocrystic garnet and kyanite in clinopyroxene-hornblende-bearing adakitic meta-tonalites from Cape Hinode, Prince Olav Coast, East Antarctica Geological Society, London, Special Publications, January 1, 2008; 308(1): 333 - 350. [Abstract] [Full Text] [PDF]
|
|