Evaluation of crustal recycling and magma formation by subduction in the Trans Mexican Volcanic Belt: New insights from the Ceboruco volcano, Mexico

跨墨西哥火山带俯冲作用的地壳循环和岩浆形成评估：墨西哥塞博鲁科火山的新见解

• 批准号: 2902362
• 金额: --
• 依托单位: University of Leicester
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2902362
• 关键词: Evaluation; crustal; recycling; magma; formation

The Trans-Mexican Volcanic Belt (TMVB) is one of the most compositionally diverse magmatic arcs on Earth and therefore constitutes a prime location for testing emerging hypotheses on arc petrogenesis and continental evolution (Gómez-Tuena et al., 2018). Recycling of upper plate crust in subduction zones, or 'subduction erosion', is a major mechanism of crustal destruction at convergent margins. Assessing the impact of eroded crust on arc magmas is, however, difficult owing to the compositional similarity between the eroded crust, trench sediment and arc crustal basement that may all contribute to arc magma formation (Ferrari et al., 2011; Straub et al., 2015). Ceboruco volcano is one of a few active volcanoes in the western part of the TMVB and is compositionally diverse ranging from mafic to rhyolite magmas (Nelson, 1980; Nunez et al., 2022). It is known that Ceboruco produced three compositionally and volumetrically different magma types including two caldera-forming explosive eruptions. However, it remains unclear how these different magmas formed, what controls their composition including distinctively high-Nb magmas enriched in LILE and HFSE resembling those of enriched intraplate magmas. Volatile bearing minerals, common to other volcanoes within the TMVB, are rare at Ceboruco raising the question whether metasomatism can be held responsible for this enrichment? This project will focus on a field-based analysis of the volcano and geochemical and petrographic study of samples collected from various domes and lavas in order to gain a better understanding leading to the formation of a range of volcanic products. The aim is to create a schematic model of the Ceboruco magma system and to see whether the basaltic to rhyolitic magmas originated from the same reservoir or whether complex processes involving partial melting of different source regions, fractional crystallisation and magma mixing and/or crustal erosion was responsible for the diverse magmatism at Ceboruco. In order to achieve this, whole rock and in-situ analyses of the mineral budget will be applied and compared to data from other subduction zone volcanoes to outline a potential magmatic system for Ceboruco. This combination provides a unique opportunity to track the eruption history of subduction-related volcanism and magma enrichment processes.

跨墨西哥火山带(TMVB)是地球上成分最多样化的岩浆弧之一，因此是检验关于弧岩成因和大陆演化的新假说的主要地点(Gómez-Tuena等人，2018年)。俯冲带上板块地壳的再循环，或称“俯冲侵蚀”，是会聚边缘地壳破坏的主要机制。然而，由于侵蚀地壳、海沟沉积物和弧形地壳基底之间的成分相似，都可能有助于弧形岩浆的形成，因此很难评估侵蚀地壳对弧形岩浆的影响(Ferrari等人，2011年；Straub等人，2015年)。Ceboruco火山是TMVB西部为数不多的活火山之一，成分多样，从镁铁质岩浆到流纹岩岩浆(Nelson，1980；Nunez等人，2022)。众所周知，Ceboruco产生了三种成分和体积不同的岩浆类型，其中包括两次形成火山口的爆炸性喷发。然而，目前尚不清楚这些不同的岩浆是如何形成的，是什么控制了它们的组成，包括富含LILE和HFSE的独特的高Nb岩浆，类似于富集的板内岩浆。TMVB内其他火山常见的含有挥发性矿物的矿物在Ceboruco很少见，这引发了这样一个问题：交代作用是否应该为这种富集物负责？该项目将侧重于对火山进行实地分析，并对从各种穹顶和熔岩中采集的样品进行地球化学和岩石学研究，以便更好地了解各种火山产品的形成。其目的是建立Ceboruco岩浆系统的示意图模型，并了解玄武岩到流纹岩岩浆是否来自同一储集层，或者涉及不同源区的部分熔融、分离结晶、岩浆混合和/或地壳侵蚀的复杂过程是否导致Ceboruco的不同岩浆活动。为了实现这一目标，将应用全岩和现场矿物平衡分析，并与其他俯冲带火山的数据进行比较，以勾勒出Ceboruco潜在的岩浆系统。这一组合为追踪与俯冲有关的火山活动和岩浆浓缩过程的喷发历史提供了独特的机会。