Eruptive history and magmatic evolution at Corbetti Caldera, Ethiopia

东非裂谷(EAR)是与活火山有关的大陆裂谷系统的典型例子。EAR的一个部分，主要的埃塞俄比亚裂谷(MER)，是由于集中在大型硅质中心的丰富的第四纪火山活动而引起人们的兴趣。然而，埃塞俄比亚近50%的人口生活在其65座火山中的一座的100公里范围内。然而，我们对该地区近代火山史的了解相当匮乏。最近的一些努力提高了我们对该地区的了解，取得了重要的发现，更好地限制了过去300公里内火山喷发的频率和规模，以及过去300公里内助长火山活动的岩浆作用。由于利用火山中心作为地热能源的潜力，该地区的火山活动日益重要。科贝蒂火山口是最南端的火山，也是MERS内最大的火山之一。最近的研究发现，来自3个火山后喷发建筑物(乌尔吉，乌尔吉)的火山喷发后发生了多次高震级事件阿尔图和查比)，并在过去10年中表现出持续的不安。虽然已经提出了过去10,000年的喷发时间，但它们在时间、规模和动力方面仍然相对较差。在~2ka BP Wendo Kohe Young浮岩单元上已经开展了一些工作，这是一个浮石层位，被认为来自乌尔吉，描述了其动力学和范围。然而，还没有对杂岩中的任何其他矿床进行这样的工作。其中一个原因是，科贝蒂的大多数矿床在地球化学和视觉上都是同质的，这使得区分它们变得困难。解决这一问题的一种方法是使用微量元素分析来帮助近端和远端矿床之间的对比，并研究岩浆过程。虽然一些作者已经进行了痕量元素分析，但需要一个更大的数据集来编目喷发事件。此外，火山喷发和喷发的控制是火山学研究的关键领域之一。科贝蒂提供了一个研究这一问题的理想场所，因为乌尔吉和查比分别几乎只展示了喷发和喷发。MER内所有火山都有一个一致的特征，那就是它们强烈的过碱性。过碱性岩浆的演化在科学文献中一直存在争议，然而，人们已达成共识，认为这些碱性岩浆主要是通过极端的分离结晶作用演化的，可能受到地壳同化的轻微影响。这一过程被归因于MER内的几座火山，然而所有这些火山都有沉积物，具有晶体货物，并在喷发的成分中显示出更广泛的范围。科贝蒂在某种程度上是独一无二的，因为大多数喷发的沉积物都是完全形成性的，这可能表明其他过程可能正在影响岩浆演化或熔体提取。

The East African Rift (EAR) is the type example of a continental rift system associated with active volcanism.One segment of the EAR, the Main Ethiopian Rift (MER), is of interest due to the abundance of Quaternary volcanism focused around large silicic centres. Almost 50% of Ethiopia's population live within 100 km of one of its 65 volcanoes however,our understanding of the recent volcanic history of the region is considerably lacking.Recent attempts to improve our understandingof the region have yielded important findings better constraining the frequency and magnitude of past eruptions and the magmatic processes that have fed volcanism over the last 300 ka.Understanding volcanism in this region is of growing importance due to the potential of utilising volcanic centres as a source of geothermal energy.Corbetti caldera is the southernmost, and one of the largest volcanic calderas within the MER.Recent studies have identified multiple high magnitude events emanating from 3 post caldera edifices(Urji, Artu and Chabbi) and demonstrated continued restlessness over the past 10 years. Whilst timings of eruptions over the last 10,000 years have been proposed, they are still relatively poorlyconstrained in terms of timing, magnitude and dynamics. Some work has been carried out on the ~2 ka BP Wendo Koshe Younger Pumice unit, a pumiceous horizons thought to be sourced from Urji,characterising its dynamics and extent.However, no such work has been done on any other deposits within the complex. One reason for this is that most deposits from Corbetti are both geochemically and visually homogenous, making distinguishing between them challenging. One way to tackle this problem is by using trace element analysis to aid correlation between proximal and distal deposits and to investigate magmatic processes. Whilst some authors have conducted trace element analysis, a significantly larger dataset is required to catalogue eruptive events. In addition, the controls on effusive and explosive volcanism is one of the key areas of investigation in volcanology.Corbetti provides an ideal place to study this as Urji and Chabbi exhibit almost exclusively explosive and effusive eruptions respectively. One feature that is consistent across all volcanoes within the MER is their strong peralkalkinity. The evolution of peralkaline magmas has been debated within scientific literature,however, a consensus has arisen that these alkaline magmas predominantly evolve through extreme fractional crystallisation which may be slightly influenced by crustal assimilation. This has been the process attributed at several volcanoes within the MER, however all these volcanoes have deposits that have a crystal cargo and display a wider range in erupted compositions. Corbetti is somewhat unique in that most eruptive deposits are completely aphyric which may indicate additional processes may be influencing magma evolution or melt extraction.