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

该项目的目的是明确了解硫元素在火山中的行为，以及在火山喷发期间和之前从火山喷出的气体中的行为。火山对当地和全球环境都有重要影响。在全球范围内，它们排放大量的火山灰和污染气体，特别是二氧化硫形式的硫磺。火山灰和二氧化硫都有冷却大气的作用。例如，在1991年菲律宾皮纳图博火山喷发期间，排放了1800万吨二氧化硫，大气在地面的冷却持续了1-3年。一个更极端的例子是1815年印度尼西亚坦博拉山的喷发。这产生了1.2亿吨二氧化硫，导致了1816年的“无夏之年”。1816年，北半球庄稼歉收，牲畜死亡，许多人挨饿。尽管全球气温有上升的长期趋势，但这种具有类似或更大气候影响的喷发在未来可能会断断续续地发生。因此，了解火山活动期间二氧化硫的排放方式和原因对该项目至关重要。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，关于火山喷发前和喷发期间二氧化硫在火山液体(熔岩)中的溶解程度的资料很少。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，有多少气体被脱气到大气中。这将使地质学家能够将以液体和火山灰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。该项目的第二个目标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物矿藏的条件。地质学家知道这些矿床的赋存环境，但关于矿石矿物在多深处变得稳定，仍有一些悬而未决的问题。例如，在感兴趣的地区，如果地壳薄或厚，是否更有可能发现具有重要经济意义的矿藏？通过在不同压力下进行实验，模拟不同的地壳厚度，该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.