An integrated accessory mineral approach to understanding post-subduction magmas and mineralisation

经济上重要的元素，如金、碲和硒通常与活跃俯冲之后的岩浆有关。这些所谓的“后俯冲岩浆”经常与伸展事件相吻合，并且通常富含碱性元素。这种岩浆作用和矿化作用之间的联系目前还不清楚。一种观点认为，在俯冲早期形成的较古老的含水岩浆在地壳深处留下了含硫化物和富含金属的堆积物。在俯冲后的延伸过程中，这些肥沃的残留物重新溶解，从而释放出金、碲和硒等元素。与以往的许多研究不同，我们将与蔡司合作，使用最先进的分析技术（使用LA-ICP-MS、XRF、西姆斯进行结构和成分分析）来分析和绘制坚固的副矿物的化学组成。这些矿物的化学成分在漫长而复杂的岩浆历史中反映了许多关键的成矿过程。重要的是，这些矿物可以承受重熔事件可能往往来自更深和未暴露的部分岩浆系统。该项目将使用锆石、磷灰石、钛铁矿和磁铁矿来开发俯冲后岩浆作用和矿化的成岩模型。这四种矿物还可能含有不太坚固的矿物，包括被认为含有许多关键金属的硫化物。

Economically important elements, such as gold, tellurium, and selenium are commonly associated with magmas that post-date active subduction. These so-called 'post-subduction magmas' regularly coincide with episodes of extension and are often rich in alkali elements. The link between this style of magmatism and mineralisation is, at present, poorly understood. One suggestion is that older, hydrous magmas formed during earlier episodes of subduction leave a residue of sulphide-bearing and metal-rich cumulates deep in the crust. During post-subduction extension, these fertile residues redissolve, thereby liberating elements such as gold, tellurium and selenium.In contrast to many previous studies, we will use state-of-the art analytical techniques (textural and composition analysis using LA-ICP-MS, XRF, SIMS) in collaboration with Zeiss to analyse and map the chemistry of robust accessory minerals. These chemical composition of these minerals fingerprint many critical ore-forming processes over what can be long and complex magmatic histories. Critically, these minerals can withstand re-melting events may often be derived from much deeper and unexposed parts of magmatic system. This project will use zircon, apatite, titanite, and magnetite to develop a petrogenetic model for post-subduction magmatism and mineralisation. These four minerals may also carry with them inclusions of less-robust minerals, including sulphides that are thought to host many key metals.