Expedition Oriented Research: Sedimentation and tectonics in Kumano forearc basin evolution, NantroSEIZE study area

探险导向研究：NantroSEIZE 研究区熊野弧前盆地演化中的沉积和构造

• 批准号: 1130078
• 负责人: Nicholas Hayman
• 金额: $ 29.92万
• 依托单位: University of Texas at Austin
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-15 至 2015-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1130078&HistoricalAwards=false
• 关键词: Expedition; Oriented; Research; Sedimentation; tectonics

Many destructive subduction-zone earthquakes nucleate beneath the sedimentary forearc basins above accretionary prisms. Such behavior certainly characterizes the Nankai prism off Japan?s Kii Peninsula where the Kumano basin sits above an out-of-sequence, or megasplay fault that is likely seismogenic. Nankai-prism behavior is largely governed by the frontal thrust system, incoming trench-sediment, and décollement zone. Yet, slope and forearc basin processes are also likely important to the mechanics of the margin. Because of drilling during IODP Expeditions 315, 316, and 319, it is possible to examine forearc basin evolution at a level not previously attainable. IODP drilling has revealed that the base of the Kumano basin roughly coincides with the Plio-Pleistocene boundary, raising the possibility that a change in sedimentation patterns affected forearc basin initiation. It is proposed to test the hypothesis that changes in sedimentation patterns from trench-fed sediment into the frontal accretionary prism to hinterland-fed slope and forearc basin deposition, coincide with changes in accretionary wedge mechanics. If climate-controlled sedimentation patterns do exert a large control on the Nankai margin tectonics, it would provide a good example of the controversial link between climate-driven sediment flux and tectonic deformation. We will test our hypothesis in the context of a margin-evolution model. Our model predicts that during the Plio-Pleistocene transition from low-to-high sediment flux, out-of-sequence thrusts and slope-basins developed along the Nankai prism in an effort to return the wedge to critical taper. The internal wedge deformation ultimately formed an incipient forearc basin. During the Pleistocene, uplift of the Japanese Alps caused significant sediment flux to the toe of the wedge and resulted in seaward advance of the accretionary prism, sediment underthrusting, and formation of the megasplay. Even greater sediment flux after the Mid-Pleistocene resulted in rapid infilling of the Kumano Basin, and loading of the seismogenic plate boundary. We will evaluate the key components of this descriptive model using a kinematic restoration of 3-D seismic reflection data, down-hole and core constraints on structural orientation and tilting histories, sedimentary provenance of key sections, and Coulomb wedge analytical solutions.Japan?s Nankai accretionary prism is the site of the 1944 and 1946 great earthquakes. Our work will generate needed datasets for the NantroSEIZE experiment, which seeks to study and monitor seismic deformation below the forearc basin, in contrast with predominantly aseismic deformation near the prism?s toe. The focus of the proposed research is of great interest to the GeoPRISMS program, leading to cross NSF programmatic impact. We will partner with Japanese colleagues, enhancing the international impact. Our education and outreach activities will be through support of a graduate student, and generating learning modules from our research. These modules will build on existing undergraduate tutorials, and be additionally tailored to UT-Austin programs that cater to predominantly minority-serving public school teachers, thereby increasing domestic public awareness about geological processes and natural hazards.

许多破坏性的俯冲带地震在增生棱柱体上方的沉积弧前盆地之下成核。这种行为肯定是日本南海棱镜的特征？在纪伊半岛，熊野盆地位于一个可能是孕震的序列外断层或巨型断层之上。南海-棱柱体的行为主要受锋面冲断系统、流入的沟槽沉积物和滑脱带的控制。然而，斜坡和弧前盆地的过程也可能是重要的边缘的力学。由于IODP第315、316和319次考察期间的钻探，有可能在以前无法达到的水平上研究弧前盆地的演化。IODP钻探显示，熊野盆地的底部大致与上新世-更新世的边界相吻合，这提高了沉积模式的变化影响弧前盆地形成的可能性。它提出了测试的假设，即沉积模式的变化，从沟喂沉积物到正面加积棱镜，以Alumand-fed斜坡和弧前盆地沉积，符合加积楔力学的变化。如果气候控制的沉积模式确实对南开边缘构造施加了很大的控制，那么它将为气候驱动的沉积物通量和构造变形之间有争议的联系提供一个很好的例子。我们将在边际演化模型的背景下测试我们的假设。我们的模型预测，在上新世-更新世的过渡，从低到高的沉积通量，顺序逆冲断层和斜坡盆地的开发沿着南开棱镜在努力返回楔临界锥度。内部楔形变形最终形成了弧前盆地的雏形。在更新世，日本阿尔卑斯山的隆起造成了显着的沉积物通量的楔趾，并导致在向海推进的增生棱柱，沉积物下冲，和形成的巨型播放。中更新世后更大的沉积物通量导致熊野盆地的快速填充，并加载孕震板块边界。我们将使用三维地震反射数据的运动学恢复、井下和岩心对构造方向和倾斜历史的约束、关键剖面的沉积物源和库仑楔分析解来评估该描述性模型的关键组成部分。1944年和1946年的大地震都发生在南海增生棱柱体上。我们的工作将产生NantroSEIZE实验所需的数据集，该实验旨在研究和监测弧前盆地以下的地震变形，与棱镜附近的主要地震变形形成对比。的脚趾。拟议研究的重点是GeoPRISMS计划的极大兴趣，导致跨NSF计划的影响。我们将与日本同行合作，增强国际影响力。我们的教育和推广活动将通过研究生的支持，并从我们的研究产生学习模块。这些模块将建立在现有的本科生教程，并额外量身定制，以满足主要是少数民族服务的公立学校教师UT奥斯汀计划，从而提高国内公众对地质过程和自然灾害的认识。