Peter Tropper, 2019. "Experimental simulation of contact metamorphism using natural quartzphyllite materials: advantages and pitfalls", Metamorphic Geology: Microscale to Mountain Belts, Silvio Ferrero, Pierre Lanari, Philippe Goncalves, Eugene G. Grosch
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Experimental investigations on metamorphic processes can be viewed as an alternative forward modelling approach of the pressure–temperature–composition (P–T–X) evolution of a rock. To obtain results as close as possible to natural observations one can use natural rocks as starting materials. The disadvantage of this method is the complex chemical compositions of the rocks and therefore these whole-rock experiments need to be evaluated not only (1) in terms of their ability to reproduce the natural observations but also (2) in their ability to reproduce theoretical calculations. In this contribution high-T low-P experiments (550–780°C and 0.15–0.6 GPa) simulating contact metamorphism of metapelites at the rims of the Permian Brixen Granite and Klausen Diorite are evaluated with respect to the points discussed above. The agreement between the experimental results and the observed mineral assemblages and mineral compositions (plagioclase, biotite) from the contact aureoles is very good. Thermodynamic testing of the experiments showed, however, a variable match between observed and calculated assemblages, ranging from satisfactory to rather poor. Finally, observed and calculated mineral compositions showed a very poor match.
Overall there is good agreement between the experiments and the natural observations, but theoretical calculations are still hampered by the complex nature of the starting materials.
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Metamorphic Geology: Microscale to Mountain Belts
CONTAINS OPEN ACCESS
In Earth evolution, mountain belts are the loci of crustal growth, reworking and recycling. These crustal-scale processes are unravelled through microscale investigations of textures and mineral assemblages of metamorphic rocks. Multiple episodes of metamorphism, re-equilibration and deformation, however, generally produce a complex and tightly interwoven pattern of microstructures and assemblages. Over the last two decades, the combination of advanced computing and technological capabilities with new concepts has provided a vast array of novel petrological tools and high-resolution/high-sensitivity techniques for microanalysis and imaging. Such novel approaches are proving fundamental to untangling the enigma represented by metamorphism with an unprecedented level of detail and confidence. As a result, the first decade and a half of this century has already seen the tumultuous development of new research avenues in metamorphic petrology. This book aims to provide a timely overview of the state of the art of this field, of newly developed petrological techniques, future advancements and significant new case studies.