TY - JOUR A1 - Ferrero, Silvio A1 - Angel, Ross J. T1 - Micropetrology BT - Are Inclusions Grains of Truth? JF - Journal of petrology N2 - Inclusions in minerals, whether fluids, melts or crystalline phases, are small pieces of the large-scale puzzle of Nature, time-consuming to investigate and often of difficult interpretation. Yet they are windows into the past of their host mineral. Mineral inclusions provide the opportunity to unravel the genesis of their host, and the increasingly refined understanding of their elastic behaviour provides the basis for alternative, equilibrium-independent geobarometry. Fluid and melt inclusions reveal information about material transfer in the Earth system, from shallow mineralization to mantle re-fertilization via subduction. The study of inclusions is thus one of the most intriguing and fertile branches of micropetrology. In this contribution, we focus on two recent developments: the use of elasticity models to extract the formation conditions of the host crystal, and the discovery and investigation of melt inclusions in metamorphic rocks. We also discuss how to evaluate the information provided by inclusions, given that they are no longer at the pressure and temperature conditions of entrapment. We discuss how to understand and quantify the changes undergone during cooling and depressurization, and how metastability-related phenomena in inclusions, such as crystallization of rare polymorphs and preservation of the original content of volatiles in fluid and melt inclusions, provide direct evidence that inclusions represent closed systems. The field of study of inclusions in minerals still has a largely untapped potential. The most fruitful avenues for future research will emerge from continuous technological innovation in analytical and imaging techniques, the application of experimental petrology, and the development and application of new theoretical models for coupled mineral behaviour under changing P-T conditions. KW - inclusions KW - nanogranitoids KW - polymorphs KW - elastic geobarometry Y1 - 2018 U6 - https://doi.org/10.1093/petrology/egy075 SN - 0022-3530 SN - 1460-2415 VL - 59 IS - 9 SP - 1671 EP - 1700 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Ferrero, Silvio A1 - Ziemann, Martin Andreas A1 - Angel, Ross J. A1 - Wunder, Bernd T1 - Kumdykolite, kokchetavite, and cristobalite crystallized in nanogranites from felsic granulites, Orlica-Snieznik Dome (Bohemian Massif): not evidence for ultrahigh-pressure conditions JF - Contributions to mineralogy and petrology N2 - A unique assemblage including kumdykolite and kokchetavite, polymorphs of albite and K-feldspar, respectively, together with cristobalite, micas, and calcite has been identified in high-pressure granulites of the Orlica-Snieznik dome (Bohemian Massif) as the product of partial melt crystallization in preserved nanogranites. Previous reports of both kumdykolite and kokchetavite in natural rocks are mainly from samples that passed through the diamond stability field. However, because the maximum pressure recorded in these host rocks is <3 GPa, our observations indicate that high pressure is not required for the formation of kumdykolite and kokchetavite, and their presence is not therefore an indicator of ultrahigh-pressure conditions. Detailed microstructural and microchemical investigation of these inclusions indicates that such phases should instead be regarded as (1) a direct mineralogical criteria to identify former melt inclusions with preserved original compositions, including H2O and CO2 contents and (2) indicators of rapid cooling of the host rocks. Thus, the present study provides novel criteria for the interpretation of melt inclusions in natural rocks and allows a more rigorous characterization of partial melts during deep subduction to mantle depth as well as their behavior on exhumation. KW - Partial melt KW - Polymorphs KW - Deep fluids KW - Nanogranites KW - Kumdykolite KW - Kokchetavite KW - Cristobalite Y1 - 2016 U6 - https://doi.org/10.1007/s00410-015-1220-x SN - 0010-7999 SN - 1432-0967 VL - 171 SP - 61 EP - 65 PB - Springer CY - New York ER -