Collaborative Research: Integrated Investigation of the Geodynamics of the Taiwan Orogeny (TAIGER)

台湾是世界上最活跃的弧-陆碰撞的结果（每年抬升3厘米，收敛8厘米）。欧亚板块和南海板块向菲律宾海板块东南偏西移动，中国东南大陆边缘的海洋岩石圈俯冲至位于菲律宾海板块之上的吕宋弧之下。约4 Ma以前，欧亚大陆边缘进入俯冲带，形成碰撞造山运动，形成台湾。台湾由平行带组成，代表了7个不同的构造地层省。碰撞发生在一个倾斜的角度，北缘首先碰撞，因此山脉在北方形成并向南传播。这种倾斜的碰撞使得空间变化被看作是时间的演变。弧吸积可以说是整个后太古代地球（甚至可能更早）大陆形成的最重要的模式。台湾提供了在世界上最活跃的弧形碰撞带研究这些过程的可能性，由于上述碰撞的倾斜性质，这种碰撞如何进行的时间视图。对于大陆岩石圈在碰撞过程中发生了什么，pi们提出了两个端元假设进行检验：1)大陆岩石圈俯冲，壳幔分离导致地壳增生，而更深的岩石圈则俯冲；2)不俯冲，但在俯冲带内淤塞，导致岩石圈不断变形增厚。大陆岩石圈在碰撞过程中所发生的两种末端情景为研究造山过程中一些最基本的问题提供了特殊的机会：大陆俯冲是否在弧-陆碰撞中起控制作用？欧亚大陆岩石圈是否在台湾下方俯冲？造山运动的一个基本问题是物质平衡。侵蚀、地壳增厚、地幔通量等因素是如何定量地相互作用的？造山带是如何演变的？-表面运动学与深层结构的关系如何？-各向异性在空间、横向和纵向上是如何变化的？s分裂方向随深度变化吗？造山带从地表到上地幔的变形是否垂直一致？为了回答这些问题，pi将进行综合地球物理成像，地震记录和地球动力学研究计划，以研究台湾的造山运动。通过结合整个区域的详细二维横断面研究和三维图像，可以表征造山带及其演化。数据采集项目包括宽带区域地震和远震记录、陆上-海上和陆地折射-反射地震剖面、大地电磁测深、岩石物理和重力建模。板块相互作用的几何形状、地壳变形模式和材料性质将为地球动力学建模提供新的定量依据。各种数据集将被整合到一个地球动力学模型中，该模型可用于测试造山的概念模型。该项目将涉及6家美国机构的合作，以及台湾和日本团体的合作和支持。中国大陆科学家参与的可能性也很大。这个项目的教育影响将是巨大的，有超过25名来自美国和外国参与机构的学生。此外，“德州实地教师”计划将邀请一名高中教师记录台湾近海地震，为德州高中教师开发相关教学模组。

0409266OkayaTaiwan is the result of the most active arc-continent collision in the world (uplift of 3cm/yr and convergence of up to 8 cm/yr). The Eurasian plate and the South China Sea have been moving to the SE wrt the Philippine Sea plate, with oceanic lithosphere of the southeast China continental margin subducting beneath the Luzon arc, which sits atop the Philippine Sea plate. Around 4 Ma ago, the margin of Eurasia entered the subduction zone, resulting in collisional orogeny that formed Taiwan. Taiwan consists of parallel belts representing 7 different tectonostratigraphic provinces. The collision is occurring at an oblique angle, with the northern margin colliding first, so that mountains are forming in the North and propagating south. This oblique collision allows spatial changes to be viewed as temporal evolution.Arc accretion is arguably the most important mode of continent formation throughout the post-Archean Earth (perhaps even before). Taiwan offers the possibility of studying these processes in the world's most active arc collision zone with a temporal view of how such collisions progress, due to the oblique nature of the collision as mentioned above. The PIs put forward two end member hypotheses to be tested concerning what is happening to continental lithosphere during the collision: 1) It is subducted, with crust-mantle detachment causing crust to accrete while deeper lithosphere is subducted; 2) It doesn't subduct, but jams up in the subduction zone, leading to continuous deformation resulting in thickening of the lithosphere. The two end-member scenarios for what is happening to continental lithosphere during the collision provide special opportunities to investigate some of the most fundamental questions of mountain building:- Does continental subduction play a controlling role in arc-continent collision? Is the Eurasian continental lithosphere subducting beneath Taiwan?- One of the fundamental issues in orogeny is mass balance. How do factors such as erosion, crustal thickening, mantle flux, etc. interact quantitatively?- How did the orogen evolve through time?- How does surface kinematics relate to deep structure?- How does anisotropy vary in space, laterally and vertically? Do the S-splitting directions change with depth? Is the deformation of the orogen vertically coherent from surface to upper mantle?To answer these questions the PIs will carry out an integrated geophysical imaging, earthquake recording and geodynamic research program to study the Taiwan orogeny. By combining detailed 2-D studies along transects and 3-D images for the whole region, the orogen and its evolution can be characterized. The data acquisition program includes broadband regional seismic and teleseismic recording, onshore-offshore and land refraction-reflection seismic transects, magnetotelluric sounding, petrophysics and gravity modeling. The geometry of the plate interactions, the mode of crustal deformation, and the material properties will provide a new quantitative basis for geodynamic modeling. The various datasets will be integrated into a geodynamic model which can be used to test conceptual models for mountain building.The project will involve collaboration from six US institutions as well as collaboration and support from Taiwanese and Japanese groups. There is also the distinct possibility of the participation of scientists from mainland China. The educational impact of this project will be large, with more than 25 students from the participating institutions, US and foreign. In addition, the "Texas Teacher in the Field" program would involve one high school teacher in recording earthquakes offshore Taiwan, developing related teaching modules for Texas high school teachers.