Behaviour of Igneous Systems and Metal endowment across Arcs (BISMArc)

弧壳的裂离可能孕育着大型热液系统，有可能形成具有经济意义的大型矿床。从弧到弧后环境的高度变化的结构和岩浆条件为研究各种岩浆和热液系统提供了独特的机会（例如，Hannington等人，2005年）。在这里，我们的目标是量化的熔化制度（物理条件，熔化和地幔源）的变化，在弧前到弧后的过渡和对金属电位的影响。岩浆挥发分（成矿）热液流体的直接贡献是已知的岛弧火山，但氧化状态，硫饱和度和硅酸盐熔体中的金属行为的岩浆脱气之间的一般联系仍然是一个积极的辩论。詹纳等人（2010年，2015年）指出了磁铁矿结晶开始对硫饱和度以及亲硫元素行为的重要性。然而，它们的磁铁矿危机可能仅限于特定的物理化学环境（如封闭系统行为、氧化状态和熔体成分等）。并且需要在不同的岩浆系统中进行研究（例如，弧到弧后过渡）和空间分辨率。在这里，我们的目标是解开地幔源和熔融的影响，金属富集在熔体和挥发物和熔体和挥发物的路径的地质框架在一个规模，是相关的资源勘探。该项目包括两个分项目，一个侧重于提供基本框架的地幔来源、熔融条件和岩浆分异，另一个侧重于海底地质学（上升路径和地球动力学）以及熔融物中金属（特别是铜、Au和所谓的关键金属）和挥发物（H2O、CO2、Cl、S）的独特行为。然而，这两个项目是密切相关的（特别是通过岩浆演化方面），需要密切合作和频繁交流。本研究的重点将是汤加-克马德克俯冲系统，该系统可随时获得大量样本材料，最近还批准了另外两艘研究游轮（ARCHIMEDES I和TongaRIFT）。

Rifting of arc crust may host large hydrothermal systems with the potential of forming large mineral deposits of economic relevance. The highly variable structural and magmatic conditions across arcs into the backarc environment provide a unique opportunity to investigate a large diversity of magmatic and hydrothermal systems (e.g., Hannington et al., 2005). Here, we aim at quantifying both the changes in the melting regime (physical conditions, melting and mantle sources) in the transition from arc front into backarc and the impact on metal potential. A direct contribution of magmatic volatiles to (ore-forming) hydrothermal fluids is known from island arc volcanoes but the general links between oxidation state, sulphur saturation and magmatic degassing on metal behaviour in silicate melts are still a matter of active debate. Jenner et al. (2010, 2015) pointed at the importance of the onset of magnetite crystallization for sulphur saturation and thus chalcophile element behaviour. However, their magnetite crisis may be restricted to specific physicochemical circumstances (such as closed system behaviour, oxidation state and melt composition etc.) and needs to be investigated in different magmatic systems (e.g., arc to backarc transition) and spatial resolution. Here, we are aiming at disentangling the influence of mantle sources and melting on the metal enrichment in melts and volatiles and the geological framework of pathways for melts and volatiles at a scale that is relevant to resource exploration. This project consists of two sub-projects, one with an emphasis on mantle sources, melting conditions and magmatic differentiation providing the basic framework and the other focused on seafloor geology (ascent paths and geodynamics) and the distinct behaviour of metals (especially Cu, Au and the so-called critical metals) and volatiles (H2O, CO2, Cl, S) in the melts. However, these two projects are closely linked (especially through the aspect of magma evolution), requiring close collaboration and frequent exchange. The focus of this study will be on the Tonga-Kermadec subduction system, where extensive sample material is readily available and two additional research cruises have been recently approved (ARCHIMEDES I and TongaRIFT).