Relating changes in melt genesis to dynamic conditions of the demise of a continental arc: Antarctic Peninsula arc

知之甚少的南极半岛火山弧是晚侏罗世早期至中新世早期的活跃大陆边缘。尽管许多探险队已经访问了该弧线的部分地区，并且对弧线的北端进行了很好的研究，但弧线的大片地区要么没有地质年代学的限制，要么没有对弧线发展的地球化学调查。最近对现有数据的一项研究（Leat和Riley， 2018年）发现，弧内有四个化学性质不同的火山群：钙碱性、高镁安山岩、埃达克岩和高锆过碱性火山群。然而，这些群体之间的限制很少，包括它们在弧发展中的时间和它们彼此之间的关系，以及它们对当时不断变化的边缘动态的意义。Leat和Riley（2018）的研究强调了弧内许多高镁安山岩的可能不寻常的特征，但由于缺乏地质年代学控制，其意义尚不确定。弧向海沟的迁移表明发生在白垩纪，但由于缺乏年龄数据，也非常缺乏约束。新的同位素年龄将限制沿弧线和横跨弧线的融化条件的变化，并将与该地区地球动力学模型的发展联系起来。该项目将利用英国南极调查局保存的特殊样本，并通过英国南极调查局的科学家莱利博士获得这些样本。此外，莱斯特大学的两位荣誉科学家Leat博士和Smellie博士将加强UoL和BAS之间的联系，他们曾是BAS的科学家，并收集了许多遗留样本。该项目的目的是了解高镁安山岩和埃达克岩如何适应南极半岛弧的发展，是什么控制了它们的起源，以及这告诉我们南极半岛弧在其发展和消亡的生命周期中熔体生产条件的变化。该项目将适合对地球化学和地质年代学感兴趣的学生，对勘探不足的地区进行分析，并对岩石成因和弧岩浆作用有浓厚兴趣。

The poorly understood Antarctic Peninsula volcanic arc was an active continental margin between the Early Late Jurassic and the Early Miocene. Although many expeditions have visited parts of the arc, and the northern end of the arc has been well-studied, there are vast tracts of the arc for which there are either no geochronological constraints or geochemical investigations of the arc development. A recent study of the available data (Leat and Riley, 2018) found four chemically distinct volcanic groups within the arc: calc-alkaline, high-Mg andesites, adakites and a peralkaline high-Zr group. However, few constraints between the groups are known, including their timing within arc development and their relation to each other, and what their significance was to the changing margin dynamics of the time. The Leat and Riley (2018) study has highlighted the perhaps unusual feature of numerous high-Mg andesites within the arc, but the significance of this is uncertain due to a lack of geochronological controls. A migration of the arc toward the trench is indicated to have occurred during the Cretaceous, but is also very poorly constrained due to the lack of age data. New isotopic ages will constrain the changing melt conditions along and across the arc and will be linked into the development of geodynamic models for the area.This project will take advantage of the exceptional collection of samples held by the British Antarctic Survey and access to it through BAS scientist Dr Riley. Furthermore, the link between UoL and BAS will be enhanced by two honorary Leicester scientists Drs Leat and Smellie who have formerly been BAS-scientists and whom collected many of the legacy samples. The aim of this project will be to learn how the high-Mg andesites and adakites fit into the development of the Antarctic Peninsula arc, what the controls their genesis, and what this tells us about the changing conditions of melt production along the Antarctic Peninsula arc during its life cycle of development and demise.The project will suit a student interested in geochemistry and geochronology, taking apart a poorly explored region, and with a keen interest in petrogenesis and arc magmatism.