Preface

Summary

The new discoveries of diamond and coesite previously thought to form only in the mantle or under cataclysmic conditions have mobilized the petrologic community into an intense search throughout the world for new occurrences of these minerals in crustal rocks. The advancement in petrologic knowledge has taken shape in three separate and interconnected spheres that have allowed us to explore further into the depths of our planet. Continued high temperature and pressure laboratory experimental synthesis produced heretofore unrecognized naturally occurring species that initiated a search for these minerals in nature. Identification and chemical analysis of micron-size mineral inclusions in resistant minerals by the electron and ion probe have provided the ground truth for verifying the presence of such ultrahigh pressure minerals (UHPM) occurring naturally. At a much different scale, geophysical seismic profiles across young orogenic zones containing UHP minerals, such as the Alps, reveal that fragments of subducted crust indeed penetrate into the mantle and that plate movements are capable of moving crustal materials to such great depths. In all new discoveries, such as this one, there has been an enthusiasm developed for discovering yet another occurrence of diamond or coesite. Nearly a decade ago these discoveries were not predicted, and so the reality of these new finds is only now being considered by the earth science community; therefore, we can look forward to new paradigms explaining the origin of UHP minerals.