Behavior of chalcophile elements in subduction zones

我将研究弧形火山形成的俯冲带中亲铜元素的行为。这些元素对浅层地壳岩石中的硫有亲和力，并包括许多我们社会所必需的金属，如铜。大多数岩石主要由硅酸盐组成，亲硫元素仅以微量浓度存在。对采矿经济有利的金属矿床出现在火山弧中，火山弧形成于大洋岩石俯冲的地方。金属矿床和俯冲带之间的这种空间联系表明了一种联系；然而，深部的金属行为鲜为人知，因为俯冲导致岩石熔融，从而导致弧形火山活动。在过去的研究中，我的团队已经证明，氧化的岩浆含有高浓度的硫和金属，氧化状态反映了下伏地幔的性质。从山上排放出大量的二氧化硫。菲律宾的皮纳图博是火山下方高度氧化的地幔的结果。我们在喜马拉雅山和南美洲的工作也表明，地幔的氧化条件受到俯冲物质的影响。地幔的硫含量很低，因此火山的大量硫排放需要从俯冲的板块中提供。我的研究将有助于回答几个问题：硫和金属是如何从俯冲板块转移到地幔，然后转移到可能喷发的岩浆中的，这些金属是如何出现在S贫瘠的地幔中的？在我们的研究中，我们将研究三种类型的岩石：那些被深度俯冲并带回地表的岩石，在造山过程中被抬升的地幔碎片，以及被火山爆发带到地表的地幔碎片。

I will investigate the behaviour of chalcophile (copper-like) elements in subduction zones where arc volcanoes form. Such elements have an affinity for sulphur in shallow crustal rocks, and include many metals that are necessary for our society, such as copper. Most rocks consist largely of silicates, and the chalcophile elements are present in only trace concentrations. Metal deposits that are economic to mine occur in volcanic arcs that are formed where oceanic rocks are subducted. This spatial association between metal deposits and subduction zones indicates a linkage; however, metal behaviour at great depths, where subduction causes melting of rocks that leads to arc volcanism, is little known. In past research, my team has shown that oxidized magmas contain high concentrations of sulphur and metals, and that the oxidation state reflects the nature of the underlying mantle. The discharge of huge amounts of SO2 from Mt. Pinatubo, Philippines, was a consequence of the highly oxidized mantle below the volcano. We have also shown from work in the Himalayas and S. America that the mantle oxidation condition is affected by the subducted material. The mantle has low sulfur, requiring the large discharge of sulfur from volcanoes to be supplied from the subducted plates. My research will help to answer several questions: How are sulfur and metals transferred from the subducting plate to the mantle, then to magmas that may erupt, and how do these metals occur in the S-poor mantle? For our research, we will study three types of rocks; those that have been deeply subducted and brought back to the surface, pieces of mantle that were uplifted during mountain building, and mantle fragments that were brought to the surface by explosive volcanoes.