Collaborative Research: Investigating the Detachment Fault Cycle at the Mid-Cayman Spreading Center

合作研究：调查开曼中部扩张中心的脱离断层旋回

• 批准号: 2104437
• 负责人: Ross Parnell-Turner
• 金额: $ 44.85万
• 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: 2022
• 资助国家: 美国
• 起止时间: 2022-01-01 至 2025-12-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2104437&HistoricalAwards=false
• 关键词: Collaborative; Research; Investigating; Detachment; Fault

Continuous paving of new seafloor at the center of the oceans is one the fundamental processes that shape Earth’s surface. Where plates spread apart relatively quickly, new crust is formed as molten rock rises to the surface, and cools to form solid crust. Where the plates move apart more slowly less molten rock fills the gap, and instead, plate separation is taken up by motion on long-lived faults called detachments. Creation of new oceanic seafloor by slip on these kilometer-scale faults is poorly understood, and is associated with hydrothermal vent systems that provide metal-rich fluids, which create ore deposits and support thriving deep-sea ecosystems. One of the best ways to understand the behavior of these faults is to study the earthquakes that they generate. This project will use earthquake data recorded by a network of seafloor seismometers, deployed on a detachment fault system where two plates are spreading apart in the Caribbean Sea, at the Mid-Cayman Spreading Center. The results will help us understand the final stages of the ‘life cycle’ of an oceanic detachment fault, by monitoring the faulting, magmatism, and hydrothermal fluid flow in the subsurface. This project supports the training of a graduate student at the University of California San Diego, and a postdoctoral investigator at Woods Hole Oceanographic Institution. It also supports the training of undergraduate students, through participation in a sea-going research expedition and summer programs.The overarching goal of this project is to understand the processes that govern the late stages of the detachment faulting life cycle, and the processes by which the fault system is abandoned, in particular. Oceanic detachments undergo a life cycle of slip and abandonment that lasts millions of years, and commonly expose upper mantle rocks on the seafloor in kilometer-scale domes called oceanic core complexes. Although they form in magma-poor settings, detachments often host high-temperature hydrothermal systems, and interactions between hydrothermal vents and ultramafic rocks generate fluids with distinct compositions. Detachment faults are associated with a delicate interplay between tectonic, magmatic, and hydrothermal processes, but how such interactions evolve over the ~2 Myr life cycle are controversial. This project will use a local microearthquake survey of the Mt. Dent massif on the Mid-Cayman Spreading Center, to constrain the tectono-magmatic processes associated with the late stage of the life cycle. A network of ocean bottom seismographs will be deployed for 6–12 months to detect microearthquake arrivals, which will be used to generate hypocenter and focal mechanism catalogs, and also to test new full-waveform methods for detecting and locating hypocenters.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

在海洋中心不断粘贴新的海底是塑造地球表面的基本过程。如果板相对较快地分开，则形成新的外壳，熔融岩石升至表面，并冷却以形成固体地壳。板移动较慢的地方，较小的熔融岩石填补了间隙，而是通过在称为脱离的长寿命断层上进行运动来弥补板的分离。通过在这些公里尺度的断层上滑倒创建新的海洋海底的新海底的理解很少，并且与提供金属丰富的烟道的水热通风系统有关，这些系统可产生矿石沉积物并支持蓬勃发展的深海生态系统。理解这些故障行为的最佳方法之一是研究它们产生的地震。该项目将使用由海底地震仪网络记录的地震数据，该数据部署在分队断层系统上，其中两个板在加勒比海中散布的两个板块，位于中期传播中心。结果将有助于我们通过监测地下的断层，岩浆和水热流动来了解海洋分离断层的“生命周期”的最后阶段。该项目支持加利福尼亚大学圣地亚哥分校的一名研究生的培训，以及伍兹霍尔海洋学机构的博士后调查员。它还通过参与海上研究探险和夏季计划来支持对本科生的培训。该项目的总体目标是了解支配分队过失的生命周期晚期的过程，并尤其放弃了断层系统的过程。持续数百万年的滑移和遗弃生命周期下的海洋脱离，通常在公里尺度的国内国内揭露海底上的地幔岩石，称为海洋核心综合体。尽管它们是在岩浆贫困的环境中形成的，但脱离经常容纳高温水热系统，而水热通风孔和超大型岩石之间的相互作用会产生具有独特成分的长笛。脱离故障与构造，岩浆和水热过程之间的微妙相互作用有关，但是在〜2 MYR生命周期中，这种相互作用如何发展是有争议的。该项目将使用中识中心中心山地块的局部微夸克调查，以限制与生命周期晚期相关的构造杂种过程。海洋底部地震仪网络将部署6-12个月，以检测微夸克到达，该网络将用于生成低核和焦点机制，并测试新的全波形式方法，用于检测和定位次数的范围，以反映NSF的范围和广泛的依据。 标准。