α/β phase transition in quartz monitored using acoustic emissions

• DOI: 10.1111/j.1365-246x.1995.tb01852.x
• Publication Date: 2007-04-03T07:39:01Z
• Authors: P. W. J. Glover; P. Baud; M. Darot; P. G. Meredith; S. A. Boon; M. LeRavalec; S. Zoussi; T. Reuschlé
• Keywords: Acoustic Emission

It is usually suggested that thermal cracking in a quartz-bearing rock results from the anomalously high volumetric expansion coefficients of quartz (e.g. Simmons & Cooper 1978). has also been recognized mismatch and mineral anisotropy contribute to materials consist polycrystalline aggregate composed several anisotropic minerals even absence temperature gradient (Friedrich Wong 1986). Experiments investigating rocks commonly involve imaging quantitative stereology crack populations induced treated various peak temperatures Friedrich Johnson 1978; Homand-Etienne Troalan 1984; Atkinson, McDonald Meredith Atkinson 1985). Here we report on acoustic-emission experiments monitor process as it occurs during heating, supported by measurements surface area, pore-fluid permeability, porosity conductivity carried out samples temperatures. The show strong microcracking at phase transition for (∼573°C) superimposed upon background due expansion. There clear higher (∼800°C) can be attributed oxidation-dehydroxylation reactions hornblende chlorite. Measurements fluid pore electrical conductivity, made have heat maximum temperatures, increases associated with major episode 500-600°C range, indicating new cracks form well-interconnected network. This confirmed SEM optical microscopy These implications continental crust, providing mechanism enabling connectivity needed explain zones depth opened this way remain open pressures existing depth. should recognized, however, these are limited their direct application since they were obtained under initially dry conditions laboratory pressures.