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Collaborative Research: Fingerprinting source-to-sink connections for deep-marine vitriclastic deposits and their association to caldera formation on Axial Seamount

合作研究：深海玻璃碎屑沉积物源-汇连接的指纹识别及其与轴海山破火山口形成的关联

基本信息

批准号：
1633936
负责人：
Brian Dreyer
金额：
$ 11.63万
依托单位：
University of California-Santa Cruz
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2016
资助国家：
美国
起止时间：
2016-09-15 至 2022-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1633936&HistoricalAwards=false
关键词：
Collaborative Research Fingerprinting source sink

项目摘要

The most active volcanic provinces in the world are under the sea. Because there is little interference from the thick crustal rocks that form the continents and because the magmas that erupt on the seafloor are closer to and more representative of their source in the mantle, submarine volcanic studies over the last 50 years have helped to transform our knowledge of magma and magma chamber dynamics and evolution. They have also improved our understanding of how the Earth and its tectonic plates work and the cycling of geochemical elements between crustal and mantle reservoirs and vice versa. This being said, with the exception of a few that peek above the ocean as islands, most seafloor volcanoes lie thousands of meters below the sea surface making it very difficult to know when or how they are erupting. This research will improve our knowledge of these processes by examining volcanically generated sediments deposited in and around the Axial Volcano caldera 1,400 meters below sealevel and about 500 km off the west coast of Oregon. The research is focused on understanding the history of Axial Volcano caldera formation and determining the mechanisms of vitriclastic formation and the applicability of their use in volcanic stratigraphic studies on undersea volcanoes. Axial is the most thoroughly monitored and sampled seamount in the world. Samples consisting of sediment cores, scoop bags, and rocks as well as bathymetric maps of the caldera at 1 meter resolution will be used in the analysis as will sedimentologic, stratigraphic, and geochemical analytical approaches. Broader impacts of the project include support of two early career scientists, graduate student training, and use of the new, major, NSF-funded Ocean Observing Initiative network. Impacts also include collaboration with two scientists whose gender is under-represented in the sciences, both of whom are employed at institutions in the EPSCoR states (i.e., states that do not receive significant amounts of federal funding) of Idaho and Rhode Island. Other impacts include international collaboration with German and French scientists and outreach to K-5 schools by producing materials for instruction on volcanoes and volcanic eruptions.Goals of the research are to define the physical and chemical evolution of Axial Seamount through the time of caldera formation and increase our understanding of submarine volcano eruption styles, fragmentation processes, and vitriclast dispersal mechanisms. Hypotheses to be tested include (1) the physical and chemical characteristics of vitriclastic deposits can be used to fingerprint their eruption, fragmentation, and dispersal origins and (2) lithofacies record magma reservoir deepening associated with magma withdrawal and caldera collapse.Technical The mineralogy of vitriclasts will be examined using X-ray diffraction and scanning electron energy dispersive spectroscopy to constrain their temperature and chemical conditions of origin. Stable isotopes of Hydrogen and Oxygen as well as Cl/K2O ratios will be used to determine magma-seawater interaction during vitriclast fragmentation and seawter assimilation into the magma. A detailed morphometric, textural, and grain size analysis will be carried out to determine if clasts are of phreatomagmatic origin. Magmatic volatiles will be measured in 80 glass inclusions in olivine by secondary ion mass spectrometry from samples taken from vitriclasts.

世界上最活跃的火山区在海底。由于形成大陆的厚地壳岩石几乎没有干扰，而且海底喷发的岩浆更接近地幔，更具有代表性，因此过去50年来的海底火山研究有助于改变我们对岩浆和岩浆房动力学和演化的认识。它们还提高了我们对地球及其构造板块如何运作以及地壳和地幔储层之间地球化学元素循环的理解，反之亦然。话虽如此，除了少数几个在海洋上方窥视的岛屿外，大多数海底火山位于海面以下数千米处，因此很难知道它们何时或如何喷发。这项研究将通过检查沉积在海平面以下1,400米、距离俄勒冈州西海岸约500公里的轴向火山破火山口及其周围的火山生成沉积物，提高我们对这些过程的认识。研究的重点是了解轴向火山破火山口形成的历史，并确定玻璃体的形成机制及其在海底火山火山地层学研究中的适用性。Axial是世界上监测和采样最彻底的海山。分析中将使用由沉积物岩心、勺袋和岩石组成的样品以及1米分辨率的破火山口测深图，以及沉积学、地层学和地球化学分析方法。该项目更广泛的影响包括支持两名早期职业科学家，研究生培训，以及使用新的，主要的，NSF资助的海洋观测倡议网络。影响还包括与两名科学家的合作，这两名科学家的性别在科学领域代表性不足，他们都受雇于EPSCoR州的机构（即，没有收到大量联邦资金的州）的爱达荷州和罗得岛。其他影响包括与德国和法国科学家开展国际合作，并通过编写火山和火山爆发教学材料向K-5学校进行宣传，研究的目标是确定火山口形成期间轴海山的物理和化学演变，并增加我们对海底火山爆发方式、破碎过程和玻璃体分散机制的了解。有待验证的假设包括：（1）玻璃质矿床的物理化学特征可用于识别其喷发、破碎、（2）岩相记录了与岩浆撤退和破火山口塌陷相关的岩浆储层加深。技术玻璃体的矿物学将使用X-射线衍射仪进行检查。射线衍射和扫描电子能量色散光谱来限制它们的温度和化学条件的起源。氢和氧的稳定同位素以及Cl/K2 O比值将被用来确定在玻璃碎屑破碎和海水同化到岩浆中的岩浆-海水相互作用。将进行详细的形态、结构和粒度分析，以确定碎屑是否为蒸汽岩浆成因。采用二次离子质谱法，对80个橄榄石玻璃包裹体中的岩浆挥发分进行了测定。