Defining geochemical signatures and timescales of melting processes in the crust: An experimental tale of melt segregation, migration and emplacement

摘要: Both the mechanism of melt segregation and nature short-range transport paths developed during partial melting can exert significant control over geochemistry because these variables influence degree equilibrium achieved between solid restite. We suggest that physical process will therefore leave a chemical signature may be detected in anatectic melts rocks which melted to form them. The experimental studies described below there are distinct differences composition derived statically distributed crack networks from those formed permeable shear zones. These exploited by natural granites estimate rates melting, extraction crystallization. As rise into upper crust, assimilation also become an important contributor final magma composition. describe use radiogenic isotopes they powerful means assessing crustal contamination models. However, evidence presented here for disequilibrium suggests isotopic not necessarily same as their source. have seen trace elements problematic well (e.g. REE our pelite experiments) compositions deviate predicted using established phase mineral-melt partitioning data. If crust really is process, would it make constraining source contaminant signatures less tractable problem? propose accepting this happen, we now position real progress. element function only its precursor, but processes at extracted. Therefore, if establish general framework modelling melts, then tool constrain mechanisms timescales extracted or assimilated. results consistent with growing body theoretical field indicating processes, ranging lower rapid, efficient occur decades less.