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

许多破坏性俯冲带地震在增生棱柱之上的沉积前弧盆地之下形成核。这种行为确实是南开“棱镜”事件的特征吗？熊野盆地位于一个乱序断层或可能发生地震的巨型天然气断层之上。南开棱柱的行为主要受锋面冲断体系、来袭海沟-沉积物和结垢带的控制。然而，斜坡和弧前盆地作用也可能对边缘的机制很重要。由于在IODP 315、316和319考察期间的钻探，可以在以前无法达到的水平上检查弧前盆地的演化。IODP钻探显示熊野盆地基底与上新世—更新世界线大致重合，提出沉积模式变化影响弧前盆地形成的可能性。为了验证从海沟沉积到前缘吸积棱镜再到腹地斜坡和弧前盆地沉积模式的变化与吸积楔力学的变化是一致的。如果气候控制的沉积模式确实对南开边缘构造有很大的控制作用，那么它将为气候驱动的沉积物通量与构造变形之间有争议的联系提供一个很好的例子。我们将在边际进化模型的背景下检验我们的假设。我们的模型预测，在上新世—更新世从低通量到高通量的转变过程中，南开棱柱发育了序外逆冲和斜坡盆地，使楔体回归到临界锥度。内部的楔体变形最终形成了早期的弧前盆地。更新世期间，日本阿尔卑斯山脉的隆升引起了大量的沉积物向楔脚的流动，导致了增生棱柱向海推进，沉积逆冲，形成了大气层。中更新世以后更大的沉积通量导致熊野盆地的快速填充和发震板块边界的加载。我们将利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限制、关键剖面的沉积物源以及库仑楔解析解来评估该描述性模型的关键组成部分。南开增生三棱镜是1944年和1946年两次大地震的发生地。我们的工作将为NantroSEIZE实验生成所需的数据集，该实验旨在研究和监测弧前盆地下方的地震变形，与棱柱附近主要的地震变形形成对比。年代的脚趾。所提出的研究重点对地质科学项目非常有兴趣，导致跨NSF项目的影响。我们将与日本同行合作，提升国际影响力。我们的教育和推广活动将通过研究生的支持，并从我们的研究中产生学习模块。这些模块将建立在现有的本科教程的基础上，并为德克萨斯大学奥斯汀分校的课程量身定制，以迎合主要为少数民族服务的公立学校教师，从而提高国内公众对地质过程和自然灾害的认识。

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.