Journal of Petrology Volume 42 Number 9 Pages 1751-1772 2001
© Oxford University Press 2001
Partial Melting of Aluminous Metagreywackes in the Northern Sierra de Comechingones, Central Argentina
1DEPARTAMENTO DE GEOLOGÍA, UNIVERSIDAD NACIONAL DE RÍO CUARTO, 5800 RÍO CUARTO, ARGENTINA
2DEPARTMENT OF GEOLOGY, UNIVERSITY OF GEORGIA, ATHENS, GA 30602, USA
We describe a suite of metamorphic and migmatitic rocks from the Sierra de Comechingones (Sierras Pampeanas of Central Argentina) that include unmelted gneisses, migmatites and refractory granulites. The gneisses are aluminous greywackes metamorphosed in the amphibolite grade and are likely to have been the protoliths for the higher-grade migmatites and granulites. Mineralogical characteristics and major and trace element compositions show that metatexite migmatites, diatexite migmatites and granulites are all melt-depleted rocks. The migmatites (both metatexites and diatexites) have undergone H2O-fluxed melting and lost 
20% melt, whereas the granulites have lost as much as 60% melt, formed chiefly by dehydration-melting of biotite. The granulites are rocks from which essentially all the granitic components have been extracted, whereas the migmatites cooled and solidified while still retaining a granitic fraction. The only evidence for the presence of melt in the study area, apart from migmatitic leucosomes, are dikes and sills of leucogranite rich in cumulate K-feldspar. These leucogranite bodies may represent the pathways along which melt was drained from the exposed rocks. Our study shows that in the Sierra de Comechingones both migmatites and granulites represent source regions of anatectic magmas, which were ‘frozen in’ at different stages of development.
KEY WORDS: migmatites; granulites; anatexis; metagreywackes; granites
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  N. HARRIS, A. McMILLAN, M. HOLNESS, R. UKEN, M. WATKEYS, N. ROGERS, and A. FALLICK Melt Generation and Fluid Flow in the Thermal Aureole of the Bushveld Complex J. Petrology, June 1, 2003; 44(6): 1031 - 1054. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. E. Johnson, T.E. Johnson, N.F.C. Hudson, and G.T.R. Droop Evidence for a genetic granite-migmatite link in the Dalradian of NE Scotland Journal of the Geological Society, May 1, 2003; 160(3): 447 - 457. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. FORNELLI, G. PICCARRETA, A. DEL MORO, and P. ACQUAFREDDA Multi-stage Melting in the Lower Crust of the Serre (Southern Italy) J. Petrology, December 1, 2002; 43(12): 2191 - 2217. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. E. Otamendi, J. D. de la Rosa, A. E. P. Douce, and A. Castro Rayleigh fractionation of heavy rare earths and yttrium during metamorphic garnet growth Geology, February 1, 2002; 30(2): 159 - 162. [Abstract] [Full Text] [PDF]
|
|