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Inclusiones fluidas en pegmatitas portadoras de estaño de la Sierra de San Luis, Argentina
| Content Provider | Semantic Scholar |
|---|---|
| Author | Montenegro, Teresita Francis Sosa, Graciela E. Mañana |
| Copyright Year | 2003 |
| Abstract | Fluid inclusions in Sn-bearing pegmatites of the Sierra de San Luis, Argentina. In the Sierra de San Luis, Argentina, Sn-enriched granitic pegmatites represent the extremes of fractional crystallization of Ordovician, syn-kinematic, meta- to peraluminous S-type granites. The pegmatites are concordantly emplaced in quartz-mica schist with N-S general strike and vertical dip. The metamorphic grade varies from green-schist facies to lower-amphibolite facies. Contacts between pegmatite and country rock are sharp and parallel to the metamorphic foliation, suggesting a late-kinematic emplacement. Microthermometric measurements of fluid inclusions in quartz reveal an early complex CO2-H2O-NaCl fluid. Inclusions are distributed in groups or in intragranular trails, and are interpreted as primary or pseudosecondary. The salinity is generally 0-7 wt% NaCl-eq., but rare high-salinity inclusions (29-32 wt% NaCl-eq.) were possibly originated in a magmatic stage. Homogenization temperatures (into liquid or vapor, occasionally critical) range from 227 to 346°C. The fluid inclusion pressures at the homogenization points (minimal trapping pressures) vary between 1500 and 2700 bars. A low salinity aqueous fluid was trapped in secondary inclusions with homogenization temperatures (into liquid) of 210-264°C, and densities of 0.76-0.85 g/cm 3 . At lower temperature (103 a 183°C), a late fracturing originated secondary fluid inclusions, which contain low salinity water (0-5wt% NaCl-eq.). The wide variation in cavity morphology, the large variation of CO 2 proportion and the total homogenization temperatures indicate immiscibility of an early complex fluid, with fluid inclusions reaching up to 100% of CO 2 due to the leakage of the aqueous fluid, induced by deformation of the country rock. Occasionally, a recrystallization event trapped part of the aqueous fluid. |
| Starting Page | 347 |
| Ending Page | 355 |
| Page Count | 9 |
| File Format | PDF HTM / HTML |
| Volume Number | 58 |
| Alternate Webpage(s) | http://www.scielo.org.ar/pdf/raga/v58n3/v58n3a06.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
