RT Journal Article
T1 Phase relations in the Cabeza de Araya cordierite monzogranite, Iberian Massif: implications for the formation of cordierite in a crystal mush
A1 García Moreno, Olga
A1 Corretgé Castañón, Luis Guillermo
A1 HOLTZ, F.
A1 García Arias, M.
A1 Rodríguez Cañas, C.
AB Experimental investigations and thermodynamic calculations of the phase relations of a cordierite-richmonzogranite from the Cabeza de Araya batholith (Cáceres, Spain) have been performed to understand theformation of cordierite. The experiments failed to crystallize cordierite in the pressure range 200-600MPa, inthe temperature range 700-975ºC and for different water activities (melt water contents between 2 and 6 wt.%).In contrast, clinopyroxene and orthopyroxene (absent in the natural mineral rock assemblage), together withbiotite, were observed as ferromagnesian assemblage in a wide range of experimental conditions. Thermodynamiccalculations, using the software PERPLE_X, describe the formation of cordierite only at 200 and 400MPa andvery low water contents, and the amount of cordierite formed in the models is always below 3.5 vol.%. The resultsindicate that cordierite is not in equilibrium with the bulk rock compositions. The most probable explanation wasthat cordierite nucleated and crystallized from a melt that is not in equilibrium with part of the mineral assemblagepresent in the magma. This “non-reactive” mineral assemblage was mainly composed of plagioclase. The silicatemelts from which cordierite crystallized was more Al-rich and K-rich than the silicate melt composition inequilibrium with the bulk composition. One possible process for the high Al content of the silicate melt is relatedto assimilation and partial melting of Al-rich metasediments. An exo-perictetic reaction is assumed to account forboth textural and geochemical observations. On the other hand, hybridization processes typical for calc-alkalineseries can also explain the high proportions of “non-reactive” minerals observed in relatively high temperaturemagmas. This study clearly demonstrates that silicate melts in a crystal mush can depart significantly from thecomposition of melt that should be in equilibrium with the bulk solid assemblage.
PB Facultat de Ciències de la Terra - Universitat de Barcelona
SN 1695-6133
YR 2017
FD 2017-12
LK http://hdl.handle.net/10272/16044
UL http://hdl.handle.net/10272/16044
LA eng
NO Olga García Moreno, Luis Guillermo Corretgé Castañón, Holtz, F., García Arias, M., Rodríguez Cañas, C. Phase relations in the Cabeza de Araya cordierite monzogranite, Iberian Massif: implications for the formation of cordierite in a crystal mush. Geologica Acta, Vol.15, Nº 4, December 2017, págs. 337-359, ISSN: 1695-6133,  DOI: 10.1344/GeologicaActa2017.15.4.6.
DS Repositorio Institucional de la Universidad de Huelva
RD 1 jun 2026