Collaborative Research: Numerical Modeling of Fluid Flow and Transport during out of Sequence Thrusting and Underplating: Application to the NanTroSEIZE Investigation Area

合作研究：乱序推进和底侵过程中流体流动和传输的数值模拟：在 NanTroSEIZE 调查区域的应用

• 批准号: 0727485
• 负责人: Shemin Ge
• 金额: $ 9.43万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-08-01 至 2012-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0727485&HistoricalAwards=false
• 关键词: Collaborative; Research; Numerical; Modeling; Fluid

Understanding the interplay between out-of-sequence thrusts, fluid expulsion, underplating, and the behavior of the plate boundary fault is of fundamental importance to the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE), but these processes have not previously been examined through fluid flow and deformation modeling. Accordingly, this modeling study will address the impact of these major processes on pore pressures and fluid flow within the prism, mega-splay fault, and plate boundary fault. The modeling will be implemented using an existing software package ABAQUS. This package offers the ability to simulate the major features important to this modeling, will allow modeling results to be reproducible by other researchers, and is flexible enough to accommodate needs of future subduction zone modeling. The model will be applied to the Kii transect of the Nankai subduction zone and used to test the following interrelated hypotheses: Hypothesis 1: The mega-splay fault system significantly alters the patterns of excess pore pressures and porosity loss within the accretionary complex. Hypothesis 2: The hydrologic role of the Nankai mega-splay system can be illuminated through observation of pore pressures, porosities, and fluid chemistry. Hypothesis 3: Underplating rejuvenates fluid expulsion at the base of the accretionary prism by transferring sediments to a different stress state and by moving the decollement zone to a less dewatered area. Although this application of the modeling is to the Kii transect of the Nankai subduction complex, an assessment of the importance of underplating and out-of-sequence thrusting for subduction zone dewatering and deformation will be useful for other subduction zones, as well as for workers in fold and thrust belts. Splay faulting and underplating are commonly inferred features that could greatly alter pore pressure and porosity distributions (and thus seismogenesis) in many subduction zones. Broader Impact Understanding seismogenic zone processes has great societal impact related to earthquake and tsunami hazards. This study will constitute an initial step in the long-term investigation of the seismogenic zone. Modeling conducted early in the investigative process can help to shape scientific strategies during drilling and monitoring. The use of the ABAQUS software package will expand the ability of the subduction zone modeling community. Model input data sets will be made available to other researchers. As an active proponent in NanTroSEIZE, Liz Screaton will directly communicate modeling results to fellow proponents and at future workshops and NanTroSEIZE-related meetings. In addition, general interest conclusions will be published in scientific journals and presented at national scientific meetings. This project will result in the training of graduate students. At University of Florida, it will be adapted to either one PhD or two M.S. students. At University of Colorado, the project work will involve a student (either MS or PhD) in the modeling. The graduate students will present at scientific meetings and the project will be a significant component of their dissertation or thesis.

了解无序逆冲、流体排出、底侵和板块边界断层行为之间的相互作用对于南开海槽地震带实验 (NanTroSEIZE) 至关重要，但这些过程之前并未通过流体流动进行检验和变形建模。因此，该模型研究将解决这些主要过程对棱柱体、巨型张开断层和板块边界断层内的孔隙压力和流体流动的影响。建模将使用现有软件包 ABAQUS 来实现。该软件包提供了模拟对该建模重要的主要特征的能力，使其他研究人员可以重现建模结果，并且足够灵活，可以满足未来俯冲带建模的需求。该模型将应用于南海俯冲带的纪伊横断面，并用于检验以下相关假设： 假设 1：巨型张开断层系统显着改变了增生杂岩内的超孔隙压力和孔隙度损失模式。假设 2：南开巨型扇形系统的水文作用可以通过孔隙压力、孔隙度和流体化学的观察来阐明。假设 3：底侵作用通过将沉积物转移到不同的应力状态并将滑脱带移动到脱水程度较低的区域，从而恢复增生棱柱底部的流体排出。尽管该模型的应用是针对南海俯冲杂岩的纪伊横断面，但对俯冲带脱水和变形的底侵和无序逆冲的重要性的评估对于其他俯冲带以及工人来说将是有用的在折叠带和推力带中。展张断层和底侵是通常推断的特征，可以极大地改变许多俯冲带的孔隙压力和孔隙度分布（从而改变地震发生）。更广泛的影响 了解震源区过程对于地震和海啸灾害具有巨大的社会影响。这项研究将构成震源区长期调查的第一步。在调查过程早期进行的建模有助于在钻探和监测过程中制定科学策略。 ABAQUS 软件包的使用将扩展俯冲带建模界的能力。模型输入数据集将提供给其他研究人员。作为 NanTroSEIZE 的积极支持者，Liz Screaton 将在未来的研讨会和 NanTroSEIZE 相关会议上直接向其他支持者传达建模结果。此外，普遍感兴趣的结论将在科学期刊上发表并在国家科学会议上提出。该项目将导致研究生的培训。在佛罗里达大学，它将适应一个博士学位或两个硕士学位。学生。在科罗拉多大学，该项目工作将涉及一名学生（硕士或博士）参与建模。研究生将在科学会议上发表演讲，该项目将成为他们论文的重要组成部分。