Extrusion, Extension and Exhumation in an Emerging Mountain Belt, Taiwan

台湾新兴山带的挤压、延伸和折返

• 批准号: 0711353
• 负责人: Timothy Byrne
• 金额: $ 23.69万
• 依托单位: University of Connecticut
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-06-01 至 2011-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0711353&HistoricalAwards=false
• 关键词: Extrusion; Extension; Exhumation; Emerging; Mountain; Extrusion; Extension; Exhumation; Emerging; Mountain

This goal of this project is to test the new hypothesis that extension in southern Taiwan initiated 1 to 2 million years ago as the Philippine Sea plate initially collided with a zone of transitional continental crust (5 to 20 km thick) followed by collision with continental crust of more typical thickness (about 30 km). The transition in collision mode initiated along-strike flow or extrusion and local areas of extension, especially in the southern Central Range of Taiwan. Field-based structural geology (brittle and ductile structural analyses) and low-temperature thermochronology (fission track and (U-Th)/He dating) coupled with seismological (focal mechanisms, cluster geometries) and GPS analysis will be carried out to determine: 1) if and when exhumation changed from relatively slow to fast rates; 2) the regional extent of the any change in exhumation rates; 3) if there has been a change from shortening to extension; 4) determine which structures accommodate extension and rock uplift; and 5) document southward propagation of specific structures, structural sequences or exhumation. The overall goal will be to document the current and past kinematics in the area and then tie the interpreted kinematic evolution to the history of uplift and exhumation as revealed by the thermochronologic data.One of the most significant recent breakthroughs in understanding processes that affect the Earth's surface is the discovery that some contractional orogenic belts also experience horizontal extension. The orogenic belt in Taiwan provides an unusual opportunity to better constrain the origin and significance of synorogenic extension. The orogen straddles the boundary between the Eurasian and Philippine Sea plates and is actively propagating as the two plates collide. In the area where the orogen is just emerging above sea level, a dense GPS network shows a broad zone of relatively fast extensional strains. The topography in this area also climbs to the maximum elevation in the collision zone (just under 4 km) and available thermochronological data suggest relatively high uplift rates. Why is this area of well-documented extension also an area of substantial rock and surface uplift? Answering this question would greatly improve understanding of processes that operate during collisonal mountain building episodes.

该项目的这个目标是测试新的假设，即台湾南部的扩展在1至200万年前开始，菲律宾海板最初与过渡性大陆壳（5至20 km厚）相撞，然后与更典型的厚度（约30 km）的大陆壳发生碰撞。碰撞模式下的过渡沿撞击或挤压以及延伸的局部区域启动，尤其是在台湾中部南部范围内。基于现场的结构地质（脆性和延性结构分析）和低温热量学（裂变轨道和（u-th）/HE日期）以及地震学（局灶性机制，群集几何）和GPS分析将进行：1）以确定：1）是否何时从相对缓慢的速度转化为快速速度，何时将刺激变化为快速快速速度； 2）任何挖掘率变化的区域范围； 3）如果从缩短到扩展发生了变化； 4）确定哪些结构适合延伸和隆起； 5）记录了特定结构，结构序列或挖掘的向南传播。总体目标是记录该地区的当前和过去的运动学，然后将解释的运动学演变与热量数据学数据所揭示的抬高和挖掘历史相关。台湾的造山带提供了一个不寻常的机会，以更好地限制同步扩展的起源和意义。造型跨越了欧亚和菲律宾海板之间的边界，并且随着两个板碰撞而积极地传播。在造山基因仅在海平面上方出现的区域中，密集的GPS网络显示出相对快速的延伸菌株的广泛区域。该区域的地形还爬升到碰撞区（不到4公里）的最大海拔，可用的热量数据表明升高速率相对较高。为什么有据可查的延伸区域也有一个巨大的岩石和地表隆起的区域？回答这个问题将大大提高人们对在山脉山区建筑情节中运作的过程的理解。