Energy-Constrained Open-System Magmatic Processes II: Application of Energy-Constrained Assimilation-Fractional Crystallization (EC-AFC) Model to Magmatic Systems 论文

摘要

Evidence for open-system magmatic processes is abundant in igneous rocks from most tectonic settings and with ages spanning most of geologic time. Accurately documenting these processes is critical for understanding magma reservoir dynamics, including the processes that lead to compositional diversity in igneous rocks, and for deciphering the thermochemical evolution of the crust and mantle. Quantitative models describing open-system processes such as assimilation-fractional crystallization (AFC) have provided significant insight into all of these, but, nevertheless, suffer from several serious deficiencies. Foremost among these are the absence of energy conservation and the lack of consideration of country rock partial melting. For a magma body undergoing AFC, a new quantitative model, Energy-Constrained Assimilation Fractional Crystallization (EC-AFC), self-consistently balances energy, species and mass while also tracking compositional variations generated in anatectic melt as country rock undergoes partial melting. EC-AFC represents a significant improvement to existing AFC models for several reasons. First, the inclusion of energy conservation provides a direct and crucial link between thermal parameters and volcanological/geological data. Second, unlike ‘classical ’ AFC that models mass and chemical properties only, EC-AFC models mass, chemical and thermal