INGEOSUR   20376
INSTITUTO GEOLOGICO DEL SUR
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Metasomatism in the lithospheric mantle beneath southern Patagonia, Argentina
Autor/es:
KOLOSOVA-SATLBERGER, OLESYA; NTAFLOS, TH.; BJERG, E. A.
Lugar:
Viena
Reunión:
Conferencia; 11th EGU General Assembly; 2014
Institución organizadora:
European Union of Geosciences
Resumen:
Mantle xenoliths from Gobernador Gregores, southern Patagonia are spinel- lherzolites, harzburgites and wherlites. A large number of the studied xenoliths have experienced cryptic and modal metasomatism. The xenoliths are mainly coarse-grained with prevalent protogranular texture but equigranular tabular and mosaic textures are present as well. Xenoliths that have undergone modal metasomatism bear hydrous phases such as amphibole, phlogopite apatite and melt pockets. The latter are of particular interest because of their unusually large size (up to 1 cm in diameter) and freshness. They consist of second generation olivine, clinopyroxene and spinel relict amphibole sulfides that are surrounded by a yellowish vesicular glass matrix. The melt pockets are found in amphiboleand/or phlogopite-bearing wehrlites and harzburgites as well as anhydrous lherzolites. Subhedral primary olivines enclosed by melt pockets show in the BSE images a dark grey margin up to 80 microns thick attributed to the reaction of the primatry olivine with melt. Fine grained spinel inclusions are always associated with the dark grey margin, indicating that they belong to the secong generation assemblage.