Chemistry of fluid inclusions in rock samples from Dronning Maud Land ...

• Main Authors: Kleinefeld, Bärbel, Bakker, R J
• Format: Article in Journal/Newspaper
• Language: English
• Published: PANGAEA 2002
• Subjects: Geological sample; GeoMaud95/96; Sampling on land; Antarc*; Antarctica; Dronning Maud Land; East Antarctica
• Online Access: https://dx.doi.org/10.1594/pangaea.736480; https://doi.pangaea.de/10.1594/PANGAEA.736480

Dense, CO2-rich fluid inclusions hosted by plagioclases, An45 to An54, of the O.-v.-Gruber- Anorthosite body, central Dronning Maud Land, East Antarctica, contain varying amounts of small calcite, paragonite and pyrophyllite crystals detected by Raman microspectroscopy. These crystals are reaction products that have formed during cooling of the host and the original CO2-rich H2O-bearing enclosed fluid. Variable amounts of these reaction products illustrates that the reaction did not take place uniformly in all fluid inclusions, possibly due to differences in kinetics as caused by differences in shape and size, or due to compositional variation in the originally trapped fluid. The reaction albite + 2anorthite + 2H2O + 2CO2 = pyrophyllite + paragonite + 2calcite was thermodynamically modelled with consideration of different original fluid compositions. Although free H2O is not detectable in most fluid inclusions, the occurrence of OH-bearing sheet silicates indicates that the original fluid was not pure CO2, ... : Supplement to: Kleinefeld, Bärbel; Bakker, R J (2002): Fluid inclusions as micro-chemical systems: evidence and modelling of fluid-rock interactions in plagioclase. Journal of Metamorphic Geology, 20(9), 845-858 ...