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，通常与活动俯冲后的岩浆有关。这些所谓的“后俯冲岩浆”经常与伸展期重合，通常富含碱元素。目前，人们对这种岩浆活动与矿化之间的联系知之甚少。一种说法是，在早期俯冲期形成的更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残留物。在俯冲后的伸展过程中，这些肥沃的残留物重新溶解，从而释放出金、碲和硒等元素。与之前的许多研究相比，我们将与蔡司合作，使用最先进的分析技术（使用LA-ICP-MS， XRF， SIMS进行结构和成分分析）来分析和绘制强大的辅助矿物的化学成分。这些矿物的化学成分表明，在漫长而复杂的岩浆历史中，有许多关键的成矿过程。至关重要的是，这些矿物可以承受再融化事件，这些再融化事件通常来自岩浆系统中更深和未暴露的部分。该项目将使用锆石、磷灰石、钛矿和磁铁矿来开发俯冲后岩浆作用和矿化的岩石成因模型。这四种矿物也可能带有不太坚固的矿物内含物，包括硫化物，人们认为硫化物含有许多关键金属。

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.