Collaborative Research: Non-equilibrium Topography and Crustal-scale Imbrication in an Arc-continent Collision, Taiwan

该项目将与台湾科学家合作，研究台湾中央山脉的变形、折返和景观演变，重点是最近发现的高海拔低起伏斑块，这些斑块横跨山脉的顶部，与造山系统预测的陡峭崎岖的地形形成鲜明对比，被认为已经达到稳定状态的地形。研究小组将测试这样一种想法，即这些低起伏地区是在岩石抬升速率最近瞬时加速之前形成的残余景观的抬升残余，并且抬升的加速是由地震层析分析的初步解释所建议的地壳规模的叠瓦作用驱动的。为了验证这些相关的假设，该团队将开展三个相关的研究：1）地貌学和宇宙成因分析（详细分析地形;详细实地绘制河流阶地图;主要使用10 Be确定低地形地区的侵蚀率）; 2）基于野外和地壳尺度的运动学分析（记录露头规模断层和运动学的空间分布、相对年龄和方向;确定主要变形机制;断层地震资料对应变椭球形状和方位的反演）; 3）热年代学研究。本研究的综合数据集有可能改变对地壳变形和景观演化的理解，这是一个活跃的弧-大陆碰撞的典型例子之一。台湾代表了地球上最活跃的构造环境之一。该岛标志着吕宋火山弧和亚洲被动边缘之间的碰撞，几十年来，这种碰撞激发了地球动力学模型来解释世界各地许多山脉带的演变。台湾的范例是，东北-西南走向的被动边缘和南北走向的火山弧之间的平行性导致了山脉带的稳定向南扩展和时间-空间的等价性，因此可以将山脉带的横截面视为特征演化中不同阶段的时间切片。此外，相对恒定的宽度的造山带导致许多工作者认为，地形稳定状态的物质流入是平衡的侵蚀。该项目旨在研究山区地带被扰乱稳态系统的偶发事件打断的想法。该项目得到地球科学部构造计划和NSF国际科学与工程办公室的支持。

This project, in collaboration with scientists from Taiwan, will study of the deformation, exhumation, and landscape evolution of the Central Range of Taiwan with focus on recently recognized patches of low relief at high elevations that straddle the crest of the range and stand in stark contrast to the steep and rugged topography predicted for an orogenic system considered to have reached steady-state topography. The research team will test the idea that these areas of low relief are uplifted remnants of a relict landscape that formed prior to a recent transient acceleration in rock uplift rate and that the acceleration in uplift was driven by crustal-scale imbrication as suggested by preliminary interpretations of seismic tomographic analyses. To test these linked hypotheses, the team will carry out three related lines of research: 1) geomorphology and cosmogenic analyses (detailed analysis of the topography; detailed field mapping of fluvial terraces; and determination of erosion rates for the areas of low relief primarily using 10Be); 2) field-based and crustal-scale kinematic analyses (documentation of the spatial distribution, relative age, and orientation of outcrop-scale faults and kinematics; determination of the dominant deformation mechanisms; and inversion of fault earthquake data for the shape and orientation of the strain ellipsoid); 3) thermochronometry studies. The integrated dataset from this study has the potential to transform understanding of the crustal deformation and landscape evolution of one of the type examples of an active, arc-continent collision.Taiwan represents one of the most active tectonic environments on Earth. The island marks the collision between the Luzon volcanic arc and the passive margin of Asia and for decades the collision has motivated geodynamic models to explain the evolution of many mountain belts around the world. The paradigm for Taiwan is that the obliquity between the northeast-southwest trending passive margin and the north-south trending volcanic arc has led to steady southward propagation of the mountain belt and a time-for-space equivalence so that cross sections of the belt can be treated as time slices for different stages in a characteristic evolution. Moreover, the relatively constant width of the orogen has led numerous workers to argue for a topographic steady state where the influx of material is balanced by erosion. This project aims to examine the idea that the mountain belt is punctuated by episodic events that perturb the steady state system.This project is supported by the Earth Sciences Division Tectonics Program and the NSF Office of International Science and Engineering.