Abstract
polymorph kyanite also has the capacity to retain tensile stresses if exhumed to Earth's surface after being trapped as an inclusion in plagioclase at P-T conditions within the kyanite stability field, with the stresses developed during exhumation sufficient to produce a transformation to anda - lusite. These results highlight the elastic environment that may arise during exhumation and provide a potential expla- nation of observed inclusions whose stability fields are well removed from P-T paths followed during exhumation. Abstract Analysis of mineral inclusions in chemically and physically resistant hosts has proven to be valuable for reconstructing the P-T exhumation history of high-grade metamorphic rocks. The occurrence of cristobalite-bear- ing inclusions in garnets from Gore Mountain, New York, is unexpected because the peak metamorphic conditions reached are well removed (>600 °C too cold) from the sta- bility field of this low-density silica polymorph that typi - cally forms in high temperature volcanic environments. A previous study of samples from this area interpreted pol- ymineralic inclusions consisting of cristobalite, albite and ilmenite as representing crystallized droplets of melt gen- erated during a garnet-in reaction, followed by water loss from the inclusion to explain the reduction in inclusion pressure that drove the transformation of quartz to cristo- balite. However, the recent discovery of monomineralic inclusions of cristobalite from the nearby Hooper Mine can- not be explained by this process. For these inclusions, we propose that the volume response to pressure and tempera- ture changes during exhumation to Earth's surface resulted in large tensile stresses within the silica phase that would be sufficient to cause transformation to the low-density (low- pressure) form. Elastic modeling of other common inclu- sion-host systems suggests that this quartz-to-cristobalite example may not be a unique case. The aluminosilicate
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