THE EFFECTS OF THERMAL METAMORPHISM ON ORGANIC MATTER IN CO3 CARBONACEOUS CHONDRITE METEORITES

摘要

Primitive carbonaceous chondrite meteorites provide a detailed record of thegeological processes and events that have shaped our solar system over the last 4.5 billion years.They contain (> 50 vol%) a fine-grained (≤ 1 μm) matrix of amorphous and crystalline silicates,oxides, sulphides and metals that have remained largely unaltered since the time they accreted intoan asteroid. The matrix of carbonaceous chondrites also contains ～5 wt% carbon in a wide varietyof organic materials including soluble molecules, kerogen-like insoluble organic matter (IOM), andcarbonaceous nanoglobules. However, due to the fine-grained and heterogeneous nature of thematrix the relationship between the mineralogy and organic materials remains poorly understood.We are investigating the effects of thermal metamorphism on crystalline materials present in thematrices of very pristine Ornans type carbonaceous chondrites, such and the relationship betweenthe organics and amorphous and crystalline silicates. The meteorites studied have a metamorphicrange from 3.0 to 3.8 as defined by Weisberg et al. , with higher petrologic type values indicatinggreater metamorphic temperatures (200 - 600 °C).