ESTUDIO PRELIMINAR DE LAS INCLUSIONES FLUIDAS EN ESPODUMENO DE LA PEGMATITA LAS CUEVAS, SAN LUIS, ARGENTINA.

MARTÍNEZ V. A.; GALLISKI M. A.; LIRA R.

AVANCES EN MINERALOGÍA, METALOGENIA Y PETROLOGÍA 2013

Fundación Universidad Nacional de San Juan

Lugar: San Juan; Año: 2013; p. 89 - 94

Preliminary fluid inclusion data from spodumene crystals of the intermediate zone of the LasCuevas pegmatite, Conlara pegmatitic district, Sierra de San Luis, Argentina, is presented. Thislithium-bearing body belongs to the LCT-family, Rare-Element class, REL-Li subclass, complextype, spodumene-subtype of granitic pegmatite. Fluid inclusion data in spodumene were examinedin terms of pegmatite petrogenetic melt-fluid evolution. Fluid inclusion petrography indicate thatmost inclusions are pseudosecondary, biphase or multiphase (daughter crystals-rich), with L>Vand absence of CO2. Fluid inclusion homogeneization temperatures (Th) range between ~276 and308°C, salinities vary from ~1 to 11 eq. wt. % NaCl, and densities from 0.7 to 0.9 g/cm3. Trapping temperatures would fall within the range of 600° to 700°C if about 4 kb of confining pressure is applied to Th-correction, based on the regional metamorphic grade of the LCT-pegmatite host. The PT path in the LiAlSiO4-SiO2-H2O stability field suggests initial crystallization of spodumene+quartz represented by daughter crystals phases devitrified from a H2O-rich, CO2-absent aluminosilicate melt, followed by progressive cooling and salinity increase controlled by subsolidus hydration reactions.