Crystallization conditions of peraluminous charnockites: constraints from mineral thermometry and thermodynamic modelling

摘要: Most igneous charnockites are interpreted to have crystallized at hot and dry conditions, i.e. >800 °C <3 wt.% H2O with an important CO2 component in the system. These metaluminous weakly peraluminous their formation involves a significant mantle-derived component. This study, contrast, investigates crystallization conditions of strongly peraluminous, metasediment-sourced from Qinzhou Bay Granitic Complex, South China. To constrain temperature-melt paths for studied charnockites, petrographic characterization was combined fluid inclusion compositional data, mineral thermometry, thermodynamic modelling. The uncertainties modelling reconstructing granitic magmas been evaluated by comparison between modelled experimental phase relations moderately evolved, granite (~70 wt.% SiO2). suggests that reproduces experimentally derived saturation boundaries 20–60 °C 0.5–1 wt.% systems ≤1–2 wt.% initial melt ~0.2 GPa. For investigated natural systems, thermometric estimates indicate orthopyroxene relatively low temperature (750–790 ± 30 °C) high content (3.5–5.6 ± 0.5 wt.%). finally solidified “cold” “wet” conditions. affords possible approach charnockite as tested here pressure (≤0.3 GPa), overall H2O-poor (≤1–2 wt.% total), but yields results increasing uncertainty high-pressure or H2O-rich systems.