Sulfidation of synthetic biotites

dc.contributor.authorTso, Jonathan Leeen
dc.contributor.departmentGeological Sciencesen
dc.description.abstractA series of hydrothermal experiments at 2000 bars have been conducted in order to investigate the systematic relation between biotite composition on the join phlogopite-annite and the composition of pyrrhotite. In an attempt to bracket the sulfide-silicate compositional pairs, three layers within a single capsule were used: 1) pyrite + Fe-rich biotite in the top, 2) sanidine + magnetite in the middle, and 3) troilite + Mg-rich biotite in the bottom. At the conclusion of a bracketing run, the biotite in the top was found to have become more Mg-rich and the biotite in the bottom was found to have become more Fe-rich while a pyrrhotite of apparently homogeneous composition was found throughout the capsule. Five equilibrium determinations at 700°C have been located: (N)<sub>Po</sub> = 0.928, (Fe/(Fe + Mg))<sub>Bi</sub> = 0.496 0.936 0.530 0.945 0.541 0.947 0.581 0.950 0.585 The data demonstrate that biotites tend to become more Mg-enriched with increasingly sulfur-rich compositions of pyrrhotite. This study can be applied to natural systems in which a pyrrhotite-biotite-magnetite-K-spar assemblage is present. Since sulfides have been observed to re-equilibrate at lower temperatures while the composition of the Fe-Mg silicates still mirror the conditions of metamorphism, silicate compositions can potentially be used as a measure of f<sub>S₂</sub> and f<sub>O₂</sub>. From this, one can attempt to calculate the properties of the vapor during the alteration of the silicates and ore genesis.en
dc.description.degreeMaster of Scienceen
dc.format.extentiii, 55 leavesen
dc.publisherVirginia Polytechnic Institute and State Universityen
dc.relation.isformatofOCLC# 8041118en
dc.rightsIn Copyrighten
dc.subject.lccLD5655.V855 1977.T85en
dc.titleSulfidation of synthetic biotitesen
dc.type.dcmitypeTexten Sciencesen Polytechnic Institute and State Universityen of Scienceen
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