Magmatic Volatiles, Unraveling the Reservoirs and Processes of the Volcanism in the Antarctic Peninsula

地幔影响构造板块的运动和地表的火山活动。了解地幔的组成和性质的一种方法是研究玄武岩的化学成分，玄武岩是由部分熔融的地幔岩石火山喷发而来的。这项研究将建立火山玄武岩中挥发性元素(氢、碳、氟、氯、硫)的预算和分布，以更好地了解地球内部的组成。挥发物影响地幔熔融、岩浆结晶、岩浆迁移和火山喷发。它们的丰度和空间分布为地幔流动和温度模型提供了重要的约束条件。此外，挥发物是地球大气和海洋的关键成分。建立地球内部和表面之间的挥发循环对于理解我们星球的长期演化是至关重要的。该项目支持布朗大学的一名研究生和研究科学家。它促进了与来自美国、德国、英国、阿根廷、韩国和日本六个不同国家的11个机构的地球化学家的合作，并利用了几个由NSF资助的美国分析设施。成果的传播将通过以下方式进行：1)同行评议的期刊、在会议上的演讲和受邀的大学讲座，2)为当地小学和高中班级举办的动手科学学习活动，以及3)通过公开讲座向普通观众宣传。在过去60年的资助研究中，南极半岛和附近的洋脊得到了广泛的调查，提供了有关岩浆活动的起源、岩石圈和软流圈地幔的成分、结构、温度和演化的信息。对于南极半岛岩浆活动的成因，人们提出了各种假说，从俯冲菲尼克斯板块脱挥发过程中地幔楔体的通量熔融，到碳酸盐软流圈和含水软流圈的绝热减压熔融，再到富挥发分交代的次大陆岩石圈地幔熔融。所有提出的假设都提到了挥发物的作用。令人惊讶的是，关于该地区玄武岩和地幔挥发性含量的数据并不存在。考虑到挥发性元素在岩浆及其来源的生成和组成中发挥的重要作用，这是地球化学数据集中的一个重大遗漏。我们的研究重点是考察南极半岛和凤凰岭上新世-新近世玄武岩中挥发分(C、H、F、S、Cl)的区域变化。我们的目标是建立地幔中挥发分的收支和分布，以了解1)在时空上近距离产生化学多样性玄武岩的过程，2)南极半岛和凤凰岭之下不均匀地幔来源的性质(岩性、成分和温度)。

The Earth's mantle influences the movement of tectonic plates and volcanism on the surface. One way to understand the composition and nature of the Earth's mantle is by studying the chemistry of basalts, which originate by volcanic eruptions of partially melting mantle rocks. This study will establish the budget and distribution of volatile elements (hydrogen, carbon, fluorine, chlorine, sulfur) in volcanic basalts to better understand the composition of the Earth's interior. Volatiles influence mantle melting, magma crystallization, magma migration and volcanic eruptions. Their abundances and spatial distribution provide important constraints on models of mantle flow and temperature. Moreover, volatiles are key constituents of the Earth's atmosphere and oceans. Establishing the cycles of volatiles between the Earth's interior and surface is of fundamental importance to understand the long-term evolution of our planet. This project supports a graduate student and research scientist at Brown University. It promotes the collaboration with geochemists from eleven institutions representing six different countries: USA, Germany, United Kingdom, Argentina, South Korea and Japan, and utilizes several NSF-funded USA analytical facilities. Communication of results will occur through: 1) peer-reviewed journals, presentations at conferences and invited university lectures, 2) hands-on science learning activities for local elementary and high school classes, and 3) outreach to the general audience through public lectures.Over the last 60 years of funded research, the Antarctic Peninsula and nearby ocean ridges have been extensively investigated providing information on the origin of the magmatism, and the composition, structure, temperature and evolution of the lithospheric and asthenospheric mantle. Diverse hypotheses have been proposed for the origin of the magmatism in the Antarctic Peninsula, from flux melting of the mantle wedge during devolatilization of the subducted Phoenix plate, to adiabatic decompression melting of a carbonated and hydrous asthenosphere, to melting of a volatile-rich metasomatized subcontinental lithospheric mantle. All proposed hypotheses invoke the role of volatiles. Surprisingly, data on the volatile contents of basalts and mantle from this region are non-existent. This is a significant omission from the geochemical data set, given the important role volatile elements play in the generation and composition of magmas and their sources. The focus of our research is to examine the regional variations in volatile contents (C, H, F, S, Cl) in geochemically well-characterized Pliocene-recent basalts from the Antarctic Peninsula and Phoenix ridge. Our goal is to establish the budget and distribution of volatiles in the mantle to understand 1) the processes responsible for the generation of chemically diverse basalts in close spatial and temporal proximity and 2) the nature (lithology, composition and temperature) of the heterogeneous mantle source beneath the Antarctic Peninsula and Phoenix ridge.