Collaborative Research (USC and UCSB): Direct Observation of Depth Variation in Fault Zone Structure Through and Below the Seismogenic Crust

合作研究（USC 和 UCSB）：直接观测发震地壳及其下方的断层带结构的深度变化

• 批准号: 0309542
• 负责人: James Dolan
• 金额: $ 34.19万
• 依托单位: University of Southern California
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-01-15 至 2007-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0309542&HistoricalAwards=false
• 关键词: Collaborative; Research; USC; UCSB; Direct

James Dolan (USC), Brad Hacker (UCSB), Charlie Sammis (USC), Ann Blythe (USC), and their German collaborator Lothar Ratsbacher (Frieberg) are studying the relationship between earthquake mechanics and fault-zone structure through multi-disciplinary analysis of the exhumed, Miocene-aged Salzach-Ennstal-Mariazell-Puchberg [SEMP] fault zone in Austria. One of their major goals is to understand whether seismic ruptures always occur on a well-defined planar structure or whether the complexity observed in exhumed fault zones plays an important role in the nucleation and propagation of earthquakes. Stated another way, is earthquake mechanics fundamentally a problem in granular mechanics, or should it be viewed primarily in terms of frictional sliding along a single slip surface? These issues are critical for the question of scaling laboratory experiments to the Earth. A related issue is the role of fault-zone structure in the long- and short-term transport of fault-zone fluids, and their role in the faulting process. Although much has been learned about these issues from structural studies of exhumed faults, seismic studies of active fault zones, and laboratory studies of the mechanics of earthquake nucleation, this overall set of issues has proven extremely difficult to address in a systematic fashion on a single fault. In their analysis of the SEMP fault zone, the PI's are exploiting a unique example of a major strike-slip fault that has been tilted during exhumation, such that a continuum of exhumation levels-from the near-surface down into the lower crust-are now exposed along strike. Moreover, the SEMP fault system has participated in its own exhumation to a limited extent, reducing potential structural overprints related to younger faulting. Their research will characterize the geometry and internal structural architecture of the SEMP fault zone throughout the entire depth range of the seismogenic crust, with a focus on the recognition of depth-dependent changes in fault-zone structure. Field studies are focusing on structural transects across the SEMP fault zone at exhumation levels ranging from the near-surface at the eastern end of the fault (Vienna pull-apart basin), within the seismogenic crust (central Austria), and down into the ductile lower crust exposed in the Tauern window of western Austria. In addition to detailed field mapping of structural fabrics, fluid-rock interactions, relative timing relationships, and variations in fault geometry, the PI's are conducting detailed analyses of fault-zone rocks designed to explore deformation at a wide range of scales using petrographic microscopy, cathodoluminescence microscopy, fluid-inclusion studies, scanning electron microscopy, and transmission/analytical electron microscopy.

James Dolan (USC), Brad Hacker (UCSB), Charlie Sammis (USC), Ann Blythe (USC), and their German collaborator Lothar Ratsbacher (Frieberg) are studying the relationship between earthquake mechanics and fault-zone structure through multi-disciplinary analysis of the exhumed, Miocene-aged Salzach-Ennstal-Mariazell-Puchberg [SEMP]奥地利的断层区。 他们的主要目标之一是了解地震破裂是否总是在定义明确的平面结构上发生，或者在挖掘断层区域中观察到的复杂性是否在地震的成核和传播中起重要作用。另一种说明是，地震力学从根本上是颗粒机械师中的问题，还是应该主要是用沿单个滑动表面滑动的摩擦滑动的？这些问题对于将实验室实验扩展到地球至关重要。一个相关的问题是断层区结构在断层区流体的长期和短期运输中的作用及其在断层过程中的作用。尽管从挖掘断层的结构研究，主动断层区域的地震研究以及对地震成核力学的实验室研究已经了解了很多，但事实证明，这一总体问题非常困难，以单个断层的系统方式解决。在对SEMP断层区域的分析中，PI正在利用一个在挖掘过程中倾斜的主要滑滑断层的独特示例，因此，将近距离的挖掘水平连续到近地壳中，现在沿着罢工沿着撞击。此外，SEMP断层系统已在有限的程度上参与了自己的挖掘，从而减少了与年轻断层相关的潜在结构层压。他们的研究将表征SEMP断层区域的几何形状和内部结构架构在地震构成外壳的整个深度范围内，重点是识别缺陷区结构的深度依赖性变化。现场研究的重点是在挖掘水平上的跨SEMP断层区域的结构样品，范围从断层东端的近表面（维也纳拉普特盆地），在地震构成壳（奥地利中部）内，再到奥地利西部Tauern窗口中的延性下甲壳。除了结构织物的详细现场映射，流体岩石相互作用，相对时机关系和故障几何形状的变化外，PI还对旨在探索岩石学显微镜的广泛尺度上探索变形的断层区岩石进行了详细分析，使用了脉冲显微镜显微镜，流化显微镜，流化显微镜，分析微观的电子，分析微观的电子，扫描和分析。