Petrological and geochemical evolution of the alkaline Mont Saint-Hilaire complex, Montreal area, Quebec, Canada

点击翻译按钮获取中文摘要

Based on intensive petrographic, petrologic, fluid inclusion and geochemical work of the past 2 years (see progress report), we will now try to constrain in detail the late-stage evolution of the Mont Saint- Hilaire complex during which an unusual mineral wealth developed. Representative mineral chemistry and stable carbon and oxygen data of late-stage carbonates and detailed mineral chemistry data of Na-Al-silicates will be collected. These will serve as key tools for reconstructing intensive parameters like temperature, pH and activities of silica, NaCl and H2O of late-stage assemblages. We will compare these data to intensive parameters in the earlier crystallized rocks from Mont Saint-Hilaire (see progress report). Relating the conditions reconstructed for the magmatic stage to the postmagmatic hydrothermal stage, continuous and discontinuous behavior in evolutionary trends will be distinguished. We will thus try to distinguish between open and closed system episodes and compare our results to similar assemblages from other alkaline complexes in order to understand and – where possible – quantify the chemical and physical parameters which control the development of these unusual late-magmatic/hydrothermal mineral assemblages.