The chemical behaviour of sulphur in magmas at high temperature and pressure

该项目的目的是对火山中硫元素的行为以及火山爆发期间和之前从火山中喷出的气体中的硫元素的行为有一个清晰的认识。火山对当地和全球环境都有重要影响。在全球范围内，它们排放出大量的火山灰和污染气体，特别是二氧化硫形式的硫。灰烬和二氧化硫都有冷却大气的作用。例如，在1991年菲律宾的皮纳图博火山喷发期间，排放了1800万吨二氧化硫，地面大气的冷却持续了1-3年。更极端的例子是1815年印度尼西亚坦博拉火山的喷发。这产生了1.2亿吨二氧化硫，导致1816年成为“没有夏天的一年”。1816年，北半球庄稼歉收，牲畜死亡，许多人挨饿。尽管全球气温长期呈上升趋势，但预计这种具有类似或更大气候影响的火山爆发在未来会偶尔发生。因此，了解火山活动中二氧化硫是如何以及为什么排放的是这个项目的核心。尽管这种火山排放物对环境具有重要意义，但令人惊讶的是，关于二氧化硫在喷发前和喷发期间溶解在火山液体（熔岩）中的程度，几乎没有可用的信息。因此，该项目的目标之一是确定在地壳深处的高压下，有多少气体被溶解在熔岩中，以及当熔岩从地壳深处移动到火山下方时，有多少气体被释放到大气中。这将使地质学家能够将以液体和灰烬形式喷发的熔岩数量与以二氧化硫形式排放的预期气候影响联系起来。该项目的第二个目的是确定与火山活动有关的具有重要经济意义的富硫矿石矿床的形成条件。地质学家知道这些矿床形成的环境类型，但对于矿石在多深的地方变得稳定，仍有未解决的问题。例如，如果感兴趣的地区地壳较薄或较厚，是否更有可能发现具有重要经济意义的矿床？通过在不同的压力下进行实验，模拟不同的地壳厚度，这个项目旨在回答这个问题。

The aim of this project is to develop a clear understanding of the behaviour of the element sulphur in volcanoes and in the gases which are expelled from volcanoes during and prior to volcanic eruptions. Volcanoes have important effects on both their local and global environments. In the global context they emit large clouds of ash and polluting gases particularly sulphur in the form of sulphur dioxide. Both ash and sulphur dioxide have the effect of cooling the atmosphere. During the 1991 eruption of Mt Pinatubo in the Philippines, for example 18 million tons of sulphur dioxide were emitted and cooling of the atmosphere at ground level lasted 1-3 years. A more extreme example is the eruption of Mt Tambora (Indonesia) in 1815. This produced 120 million tons of sulphur dioxide which led to the "year without summer" of 1816. In the Northern Hemisphere in 1816 crops failed, livestock died and many people starved. Such eruptions with similar or greater climatic effects can be expected episodically in the future despite the long-term trend of increasing global temperatures. Understanding how and why sulphur dioxide is emitted during volcanic activity is, therefore, central to this project. Despite the environmental importance of such emissions from volcanoes it is surprising that there is little information available on the extent to which sulphur dioxide dissolves in volcanic liquids (lavas) prior to and during eruption. One of the aims of the project is therefore to determine how much of the gas is dissolved in lavas at high pressures deep in the Earth's crust and how much is degassed to the atmosphere as the lava moves from deep in the crust to just underneath the volcano. This will enable geologists to connect the amounts of lava erupted as liquid and ash to the anticipated climatic effects in the form of sulphur dioxide emitted.A second aim of the project is to determine the conditions under which economically important deposits of sulphur-rich ore minerals occur in association with volcanic activity. Geologists know the kinds of environment in which these deposits occur, but there are still unresolved questions about the depths at which the ore minerals become stable. Are, for example, economically important deposits more likely to be found if the crust is thin or thick in the area of interest? By performing experiments at different pressures, simulating different crustal thicknesses, this project aims to answer that question.