Mechanics and Applications of Titanium Isotope Fractionation in Terrestrial Magmas

地球和月球表面的岩浆喷发为研究地球和月球地幔的成分不均匀性和动力学以及地壳岩浆库中的岩浆演化提供了广泛的机会。然而，经典的地球化学工具往往给出不完整或模糊的答案的重要问题，如：什么矿物参与部分熔融和岩浆演化？地幔源区和岩浆的含水量是多少？过去火山活动的构造背景能从岩浆成分推断出来吗？这个博士项目的目的是使用新的钛稳定同位素系统来回答这些问题。在可用于同位素研究的一系列化学元素中，钛具有独特的能力，能够单独追踪氧化物矿物在岩浆成因和演化中的参与[1]。 学生将对岩浆岩及其矿物进行超高精度的Ti稳定同位素测量[2]，以研究与陆地和月球岩浆的生成和演化有关的一系列问题。分析工作将在卡迪夫大学新成立的最先进的同位素地球化学实验室进行。此外，学生将使用卡迪夫大学最近安装的FEG-SEM（场发射枪-扫描电子显微镜）设备来确定选定样品中钛的预算。该系统的目的是使矿物成分的快速绘图在高空间分辨率在大面积。组合的数据集将允许学生实现以下研究目标：1。确定部分熔融和岩浆分异过程中Ti同位素的分配效应.测量一系列月球样品的Ti稳定同位素组成，以模拟月球岩浆海的演化.评价岩浆分异过程中熔体水含量和氧逸度对Ti同位素行为的影响.确定一系列陆地熔岩的Ti稳定同位素组成，并在这样做时，确定它们的含水量和它们所处的构造环境。 总的来说，这个项目将使人们更清楚地了解地球和月球上岩浆的生成和演化。参考文献：[1] Millet M-A et al.（submitted to EPSL）Titanium stable isotope investigation of the magmatic processes on the Earth and Moon[2] Millet M-A and Daufas N.（2014）通过双尖峰高分辨率MC-ICP-MS进行的超精密钛稳定同位素测量J. Anal.原子Spectrom.，2014年，1444-1458

Magmas erupted at the surface of the Earth and Moon offer a wide array of opportunities to study the compositional heterogeneity and dynamics of the terrestrial and lunar mantles, as well as magma evolution in crustal magma reservoirs. However, classical geochemical tools often give incomplete or ambiguous answers to important questions such as: what minerals are involved during partial melting and magma evolution? What is the water content of the mantle source and resulting magma? Can the tectonic setting of past volcanism be inferred from magma compositions?The aim of this PhD project is to use the novel titanium stable isotope system to provide answers to these questions. Amongst the flurry of chemical elements available for isotopic study, titanium has the unique ability to be able to solely trace the involvement of oxide minerals in magma genesis and evolution[1]. The student will perform ultra-high precision Ti stable isotope measurements[2] of magmatic rocks and their minerals to study a range of questions related to the generation and evolution of terrestrial and lunar magmas. Analytical work will be carried out in the newly set up state-of-the-art isotope geochemistry laboratory at Cardiff University. In addition, the student will use the recently installed FEG-SEM (Field Emission Gun - Scanning Electron Microscope) facility at Cardiff University to determine the budget of Ti in selected samples. This system is designed to enable rapid mapping of mineral compositions at high spatial resolution over large areas.The combined dataset will allow the student to attain the following research objectives:1. Determine Ti isotope partitioning effects during partial melting and magma differentiation.2. Measure the Ti stable isotope composition of a range of lunar samples in order to model the evolution of the lunar magma ocean.3. Evaluate the effects of melt water content and oxygen fugacity on the behaviour of Ti isotope during magma differentiation.4. Determine the Ti stable isotope composition of a range of terrestrial lavas and, in doing so, their water content and the tectonic context in which they were emplaced. Overall, this project will allow for a much clearer understanding of magma generation and evolution on the Earth and Moon. References:[1] Millet M-A et al. (submitted to EPSL) Titanium stable isotope investigation of magmatic processes on the Earth and Moon[2] Millet M-A and Dauphas N. (2014) Ultra-precise titanium stable isotope measurements by double-spike high resolution MC-ICP-MS J. Anal. At. Spectrom., 2014, 1444-1458