台湾东南部浅变质增生楔中与造山带平行的挤压作用

Orogen-parallel compression took place in the slightly metamorphosed accretionary prism in the southeastern segment of the active Taiwan orogen, a product of oblique arc-continent collision, in contrast to regional compression perpendicular to the orogen. Structural analysis, combined with thermochronology and numerical simulation, will in this project be performed to examine this peculiar phenomenon. The manifestation, distribution, relative age and deformation intensity of the orogen-parallel compression, as well as the spatial and temporal relationship with the orogen-perpendicular compression, will be observed and determined in the field, from which we will infer the possible mechanisms for the orogen-parallel compression. A coupled geomorphic-thermal history in the southern Taiwan orogen will be restored to address the role of the orogen-parallel compression in the uplift. Finally, a series of mechanical-thermal models for different mechanisms will be setup and solved, and their results will be compared, under the constraints of structural observations, thermochronological data, GPS surface displacements and the crust or lithosphere structures beneath, to appraise the factors controlling or influencing the compression and, further, to highlight its dynamic implication in the frame of oblique are-continent collision. This bottom-to-top study will enhance our understanding the process of arc-continent collision.

与造山带平行的挤压作用出现在台湾造山带东南部浅变质增生楔里，尽管整体上处于由斜向弧-陆碰撞形成的与造山带垂直的挤压环境。本项目将以这种特殊的挤压作用为研究对象，通过构造分析、热年代测定和数值模拟，查明其表现类型、分布特征、相对形成时代、变形程度及其与造山带垂直的挤压作用的时空关系，推断其可能的各种形成机制，并精确地恢复出台湾造山带南部的隆升剥蚀史，确定该挤压作用对造山带隆升剥蚀的贡献大小，然后建立和求解不同形成机制的变形-热模型，在构造观察、热年代学、现代地壳位移、地形高程和岩石圈结构等多方面数据的约束下从中找出影响或制约该挤压作用的主要因素，揭示其所反映的构造动力学内涵，期望由此深入理解弧-陆碰撞造山过程。

作为晚新生带代以来欧亚大陆与吕宋火山弧斜向碰撞的产物，台湾造山带是世界上研究弧–陆碰撞过程的少有理想场所之一。本项目以台湾南部增生楔中平行造山带的挤压变形构造为研究对象，查明了它们的表现形式、分布范围、形成时代和动力学背景。这些变形构造具有褶皱或重褶皱、褶劈理、顺层石英脉表面的滑线等主要类型，产出在最新出露的碰撞点（台东县城）之南，形成在准稳态造山楔演化的晚期阶段，与出露碰撞点不断地向南扩展密切相关。这一认识加深了对台湾造山带形成和演化的理解，有助于我们今后研究古老造山带内平行造山带的挤压作用和弧–陆碰撞造过程。