The Mamil Choique granitoids located in the SW border of the North Patagonian Massif consist of three peraluminous units: the banded Huenchuquil tonalites and granodiorites (HTG) and the Cerro Mojón biotite-muscovite monzogranites (CMG), which are intruded by the Nahuelfil monzogranites (NG). According to their major and trace element relations, as well as a comparison with experimentally produced melts, HTG are compatible with partial melting of mafic source rocks at variable H2O contents; residual garnet is suggested by HREE depletion that indicates a minimum P of 9-10 kbar during melting. The CMG would have formed from partial melting of supracrustal fertile lithologies (biotite-bearing) in the presence of H2O-bearing volatile phase that resulted in Sr-rich, moderately depressed HREE melts, likely produced within the garnet stability field (7-10 kbar). The intrusive NG display distinct geochemical signatures (low Sr, no HREE depletion) and general major element ratios akin to the experimentally produced melt at low P (≈5 kbar). Regional constraints indicate that coeval HTG and CMG emplacement took place along a decompressing path slightly postdating the climax of regional metamorphism in the host Cushamen Formation. Later NG intrusion would have occurred at upper crustal levels. © 2007 Elsevier Ltd. All rights reserved.
Documento: | Artículo |
Título: | Geochemistry of the Mamil Choique granitoids at Rio Chico, Río Negro, Argentina: Late Paleozoic crustal melting in the North Patagonian Massif |
Autor: | López de Luchi, M.G.; Cerredo, M.E. |
Filiación: | INGEIS, CONICET, Instituto de Geocronología y Geología Isotópica, Pabellón INGEIS, C1428EHA Buenos Aires, Argentina CONICET, Departamento de Ciencias Geológicas, Facultad de Ciencias Exactas y Naturales, C1428EHA Buenos Aires, C1428EHA Buenos Aires, Argentina |
Palabras clave: | Geochemistry; Mamil Choique granitoids; North Patagonian Massif; Partial melting; Upper Paleozoic; emplacement; granitoid; granodiorite; igneous geochemistry; igneous intrusion; Paleozoic; partial melting; source rock; tonalite; trace element; Argentina; Patagonia; Rio Negro [Argentina]; South America |
Año: | 2008 |
Volumen: | 25 |
Número: | 4 |
Página de inicio: | 526 |
Página de fin: | 546 |
DOI: | http://dx.doi.org/10.1016/j.jsames.2007.05.004 |
Título revista: | Journal of South American Earth Sciences |
Título revista abreviado: | J. South Am. Earth Sci. |
ISSN: | 08959811 |
Registro: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_08959811_v25_n4_p526_LopezdeLuchi |