Collaborative Research: Integrated He-CO2-N2 Isotope and Petrologic Study of Volatiles Cycling via the New Zealand Subduction System

合作研究：新西兰俯冲系统挥发物循环的 He-CO2-N2 同位素综合和岩石学研究

• 批准号: 1624280
• 负责人: Paterno Castillo
• 金额: $ 37.64万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2023-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1624280&HistoricalAwards=false
• 关键词: Collaborative; Research; Integrated; He; CO2

Knowledge of the cycling of volatiles such as water (H2O), carbon dioxide (CO2), and molecular N (N2) at Earth's convergent margins is fundamental to understanding the role of fluids in a variety of processes related to plate tectonics on Earth. In order to fully assess the impacts of human-related ("anthropogenic") processes on our surface environment (atmosphere, oceans, and biosphere), we must understand the natural (non-anthropogenic) processes contributing to environmental change, at all time scales. There is no better example of this need than that relating to the buildup of CO2 in the atmosphere and its likely effect on global mean surface temperature and the myriad other related processes (change in ocean surface water temperature, ocean circulation, polar ice melting, etc.). Understanding these processes is predicated on a quantitative assessment of the mass balance of volatiles entering subduction zones versus the fraction returned to the surface in fore-arc, volcanic front, or back-arc localities, versus the proportion transported into the deeper Earth (to depths greater than 150 km, in the mantle). Huge uncertainties on flux estimates of volatiles returned directly to the surface versus those subducted to the deeper mantle remain, and prevent assessments of both long- and short-term cycling histories of key volatiles between Earth's interior and external reservoirs.In this study, the research team will investigate the cycling of volatiles in the well-characterized New Zealand North Island subduction system where input and output fluxes of specific volatiles (CO2, N2, and noble gases such as He and Ar) can be well constrained. The proposed study area, a combination of the Hikurangi Margin, Axial Ranges, Taupo Volcanic Zone and Hauraki Rift Zone, comprises a forearc-volcanic front-backarc profile providing a crucial test of the mass balance of these key volatiles between sedimentary and oceanic lithosphere inputs at the Hikurangi Trench to output via magmatic, geothermal and groundwater activity in various tectonic regimes of the North Island. The volatile input characteristics will be constrained using sediment cores from ODP Site 1124, DSDP Site 317, and an upcoming IODP leg, whereas output volatile characteristics and fluxes will be provided by extensive on-shore sampling of ~100 sites at strategically-placed localities throughout the North Island. The approach will be underpinned by thermodynamic modeling of slab volatile release utilizing Perple_X and other software and composite profiles of incoming sediment/basement. Taken together, the combination of combined petrologic-geochemical-geothermal approaches at the NZ subduction zone offers the tantalizing prospect of providing well-constrained solutions to the question of recycling efficiencies for key volatiles through subduction systems, and a clearer understanding of fundamental processes (e.g., slab composition, P-T regime, plate-coupling and upper plate structure) involved in controlling subducted volatile release/retention properties.

了解挥发物（H2O），二氧化碳（CO2）和分子N（N2）等挥发物的循环知识对于理解流体在与地球上板块构造相关的多种过程中的作用至关重要。为了充分评估与人类相关（“人为”）过程对我们的表面环境（大气，海洋和生物圈）的影响，我们必须了解在所有时间尺度上有助于环境变化的自然（非人为）过程。没有比与大气中二氧化碳积聚及其对全球平均表面温度和无数其他相关过程的影响（海洋地表水温，海洋循环，极地冰熔化等的变化）的可能性更好的例子。 ）。理解这些过程的基于对进入俯冲区的质量平衡的定量评估，而弯曲区的质量平衡与返回的分数返回到表面，以arc，火山阵线或背面的区域为基础，而不是传输到更深的地球的比例（到深度（到深度）大于150公里，地幔）。对挥发物的通量估计值的巨大不确定性直接返回到表面与俯冲到更深地幔的挥发物，并防止评估地球内部和外部储层之间关键挥发物的长期和短期循环历史。在这项研究中，这项研究，这项研究团队将研究北岛俯冲良好的北岛俯冲系统中挥发物的循环，在该系统中，特定挥发物（CO2，N2和诸如HE和AR等贵族气体）的输入和输出通量可能受到良好的限制。拟议的研究区域是Hikurangi边缘，轴向范围，陶波火山区和Hauraki Rift区的组合，包括前牙前 - 沃尔克尼式前后 - ackarc概况，可对这些沉积物和大洋洲岩层输入之间的质量平衡进行至关重要的测试。在北岛各种构造政权中，通过岩浆，地热和地下水活动在Hikurangi沟渠中输出。挥发性输入特性将使用ODP站点1124，DSDP站点317和即将到来的IODP腿的沉积物芯来限制，而在整个〜100个站点的广泛采样则在整个战略平台的地点上，将提供输出的挥发性特征和通量。北岛。通过使用Perple_X和其他软件以及传入的沉积物/地下室的其他软件以及复合概况的平板挥发性释放的热力学建模将为该方法提供基础。综上所述，NZ俯冲带的岩石学 - 地球化学 - 地球化地形方法的结合提供了诱人的前景，即通过俯冲系统为关键挥发性的回收效率提供良好的解决方案，并对基本过程有更清晰的理解（例如。 ，平板组成，P-T状态，板耦合和上层结构），涉及控制俯冲的挥发性释放/保留特性。