Fluids in Continental Fault Zones: Evidence From Neomineralized Clays

断层岩中新生成的粘土保留了断层作用期间存在的流体的同位素特征，并将用于约束浅断层系统的管道和流体的主要来源。研究地壳断层系统的流体渗透和循环测试的假设，即起源于地表的流体是走滑断层和正断层系统中的主导相。该研究项目将使用成对的氧和氢同位素测量新生长的伊利石从一套剥离（正常）断层系统在美国西南部和大陆走滑断层（圣安德烈亚斯断层，阿尔卑斯断层，北安纳托利亚断层）。这些断层含有新矿化粘土，是主要大陆断层系统的研究实例。野外方法利用地表取样和最近的岩芯，而实验室工作包括稳定和放射成因分析，并得到各种样品表征研究的支持，研究天然断层系统中的流体循环对于了解上地壳中流体的作用至关重要，这对断层的强度和地震成因以及经济矿床的形成具有重要意义。该研究方法可应用于世界各地的许多断层系统，以研究变质（深部）和流星（地表）流体的相对贡献，因此具有广泛的应用潜力。这个领域和实验室项目包括密歇根大学的研究生和本科生，并涉及与几个领域和实验室专家的国际合作。对青年科学家的培训大大有助于满足未来科学、数学和工程领域对人力资本的需求。研究结果将发表在专业文献中，并插入适当的公共宣传和教学环境中，以及团队成员的科学报告中。

Newly-grown clays in fault rock preserve the isotopic signature of fluids that were present during faulting, and will be used to constrain the plumbing of shallow fault systems and the dominant source of fluids. Examining fluid infiltration and circulation of crustal fault systems tests the hypothesis that fluids originating at the surface are the dominant phase in strike-slip fault and normal fault systems. This research project will use paired oxygen and hydrogen isotopic measurements on newly-grown illite from a suite of detachment (normal) fault systems in southwestern United States and continental strike-slip faults (San Andreas Fault, Alpine Fault, North Anatolian Fault). These faults contain neomineralized clays and are well-studied examples of major continental fault systems. The field approach utilizes surface sampling and recent drill core, while the laboratory works involves stable and radiogenic analyses, supported by various sample characterization studies.Studying fluid circulation in natural fault systems is fundamental to understanding the role of fluids within the upper crust, which has major implications for the strength and seismogenesis of faults, and the formation of economic deposits. The approach in this study can be applied to many fault systems around the world to examine the relative contributions of metamorphic (deep) and meteoric (surface) fluids, so it has excellent potential for broad application. This field and laboratory project includes graduate and undergraduate students at the University of Michigan, and involves international collaboration with several field and laboratory experts. The training of young scientists contributes significantly to tomorrow's needs for human capital in science, math and engineering fields. Results will be published in the professional literature and inserted in appropriate public outreach and teaching setting, as well as scientific presentations by team members.