Controls on the porphyry Cu-Au mineralizing potential of magmas in continental collision settings

本项目旨在评价岩浆因素对大陆碰撞背景下岩浆斑岩铜金成矿潜力的影响。一种流行的观点是，碰撞后富钾岩浆的高生育力源于俯冲相关岩浆活动前一阶段沉积在下地壳的富硫化物堆积的部分熔融。这一假设将采用双重方法进行检验，包括对自然样本的实验和研究。在实验中，将天然的含硫化物堆积物置于高压和高温下诱导部分熔融，得到的流动产物将在其组成、氧逸度以及硅酸盐熔体中硫、水和金属的丰度方面得到彻底的表征。对自然样品的研究旨在：(1)表征额外的下地壳堆积物，作为实验的起始材料；(2)重建与矿化和贫瘠系统相关的一些自然碰撞后岩浆的组成、形成条件和金属含量，以便与实验结果直接比较。

The aim of this project is to evaluate the influence of magmatic factors on the porphyry Cu-Au mineralizing potential of magmas in continental collision settings. A popular view is that the high fertility of postcollisional, potassium-rich magmas stems from the partial melting of sulfide-rich cumulates that were deposited in the lower crust during a previous stage of subduction-related magmatism. This hypothesis will be tested using a dual approach that involves both experiments and studies on natural samples. In the experiments, natural, sulfide-bearing cumulates will be subjected to high pressures and temperatures to induce partial melting, and the obtained run products will be thoroughly characterized with regard to their composition, the oxygen fugacity, and the abundances of sulfur, H2O and metals in the silicate melt. The studies on natural samples aim at: (1) characterizing additional lower crustal cumulates that can be used as starting materials for the experiments, and (2) reconstructing the composition, formation conditions and metal content of a number of natural, postcollisional magmas associated with both mineralized and barren systems, such that the results can be directly compared with those obtained from the experiments.