Experimental determination of mantle rheology

地球表面最活跃和最具破坏性的现象，火山和地震，都起源于发生在地幔中的动态过程。这些现象是地幔中发生热对流的结果。地幔的对流发生在十亿年以上的时间尺度上，但本质上类似于在一锅水里发生的过程，在这种过程中，物质在底部加热，上升，到达表面并冷却。这些冷却的物质随后下沉，到达底部时再次加热，形成对流循环。为了了解地球的对流循环及其破坏性的副作用，我们需要研究地幔中矿物质的流动是如何随着温度、压力和其他参数的变化而变化的。这是通过在地幔中存在的条件下变形矿物样本来实现的。直到最近，人们还只能在地幔顶部400公里处的压力下进行变形实验。然而，随着一种新的实验设备的发展，变形t杯，现在有可能在地幔顶部700公里的条件下进行实验。地球顶部2500公里处的所有主要矿物都存在于顶部700公里处；因此，这项研究将能够描述几乎整个地幔的强度和流动特性。在这项研究中，我将使用新的仪器进行实验，测量压力、温度等参数对地幔矿物强度的影响。这些知识将用于更详细地了解地幔中发生的动力学过程，这反过来将有助于更好地了解地震和火山爆发。

The most active and destructive phenomena of the Earth's surface, volcanoes and earthquakes, have their origin in dynamic processes that take place in the mantle. These phenomena are a consequence of thermal convection taking place in the mantle. Convection in the Earth's mantle takes place over a billion year time-scale but in essence is similar to the processes taking place in a simmering pan of water, where material is heated at the bottom, rises, reaches the surface and cools. This cool material then sinks and when it reaches the bottom is heated again, in a convective cycle. In order to understand the Earth's convective cycle and its destructive side effects we need to investigate how flow of the minerals present in the mantle changes as a function of temperature, pressure and other parameters. This is done by deforming samples of the minerals under the conditions present in the mantle. Until recently, it was only possible to perform the deformation experiments at pressures found in the top 400km of the mantle. However, with the development of a new piece of experimental apparatus, the Deformation-T-Cup, it is now possible to perform experiments at conditions relevant to the top 700km of the mantle. All the major minerals present in the top 2500km of the Earth are present in the top 700km; therefore this study will be able to characterise the strength and flow properties of almost the entire mantle. In this study I will use the new apparatus to perform experiments measuring the effects of pressure, temperature and other parameters on the strength of mantle minerals. This knowledge will be used to gain a more detailed understanding of the dynamics processes taking place in the Earth's mantle, which in turn will assist in greater understanding of earthquakes and volcanic eruptions.