Magmatic volatiles and ore metals released from intraoceanic arc magmas: constraints from high pressure experiments and melt inclusions for Brothers volcano, Kermadec arc

洋内弧岩浆释放的岩浆挥发物和矿石金属：来自克马德克弧兄弟火山高压实验和熔融包裹体的限制

• 批准号: 429243206
• 负责人: Professor Dr. Francois Holtz, Ph.D.
• 金额: --
• 依托单位: Institut für Mineralogie
• 依托单位国家: 德国
• 项目类别: Infrastructure Priority Programmes
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/429243206?language=en
• 关键词: Magmatic; volatiles; ore; metals; released

The main goal of IODP Expedition 376 (conducted in 2018) was the understanding of the magmatic-hydrothermal system and associated metal ore deposits (e.g., Cu+Au) at intraoceanic volcanic arcs. The expedition focused on the sampling of Brothers volcano of the Kermadec arc, that produces evolved dacitic to rhyolitic melts, in contrast to several other volcanic systems along the Kermadec arc. Brothers volcano has also the particularity to be extremely Cl-rich with a large compositional variability (e.g., alkali and alumina content, Mg#) and the aim of this proposal is to unravel the nature and composition of magma chamber-derived volatile phases (e.g., single-phase fluid or two-phase brine and vapor) as well as their effect on fractionation trends and metal enrichment during differentiation.This objective will be achieved with three complementary analytical and experimental tasks: 1) the origin of the felsic magmas, the fractionation and differentiation processes will be investigated based on the major element analysis of matrix glasses and glass inclusions, 2) the magma storage conditions and the role of volatiles, especially Cl and H2O, on the fractionation of magmas will be constrained from high pressure crystallization experiments and 3) the role of volatiles and oxygen fugacity for ore metals (e.g., Fe, Cu, Zn, W, Au) enrichment will be estimated based on trace element analysis of glass inclusions in plagioclase and clinopyroxene. Most glass inclusions contain quench crystals and bubbles and need to be re-homogenized at high pressure. The combination of the three work packages will allow us to track the evolution of metal concentrations in Cl-rich magmatic systems during differentiation and at the magmatic-hydrothermal stage.

IODP Expedition 376（于2018年进行）的主要目标是了解岩浆 - 热热系统和相关的金属矿石沉积物（例如Cu+Au）在始终火山弧线上。这次探险重点是对克马德克（Kermadec Arc）的兄弟火山的采样，该火山产生了发展为流纹岩融化的河畔，与沿克马底克弧线沿岸的其他几个火山系统相比。兄弟火山还具有极大的特殊性，具有较大的组成可变性（例如碱和氧化铝含量，mg＃），该提议的目的是揭示岩浆室衍生的挥发性阶段的性质和成分通过三个互补的分析和实验任务实现：1）基于基质玻璃和玻璃包含的主要元素分析，将研究长英质岩浆的起源，分馏和差异过程，2）岩浆存储条件以及挥发性的作用，尤其是CL和H2O的作用，尤其是在高压结晶的基础上，以及3个型号的摇摆实验。矿石金属（例如Fe，Cu，Zn，W，Au）富集将根据斜长石和Clinopyroxene中玻璃夹杂物的痕量元素分析进行​​估计。大多数玻璃夹杂物包含淬灭晶体和气泡，需要在高压下重新调解。这三个工作包的组合将使我们能够在分化和岩浆 - 热热阶段跟踪富含Cl的岩浆系统中金属浓度的演变。