Role of the Ryukyu Arc towards the Taiwan orogeny

琉球岛弧对台湾造山运动的作用

基本信息

批准号：
21540439
负责人：
MATSUMOTO Takeshi
金额：
$ 2.75万
依托单位：
University of the Ryukyus
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2009
资助国家：
日本
起止时间：
2009 至 2011
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-21540439/
关键词：
台湾琉球弧造山運動

项目摘要

The southwestern Ryukyu area is the key to understanding the role of the arcuate-shaped trench-arc-backarc system towards the orogeny of Taiwan ; with the viewpoint of the northwestern termination of subduction of the Philippine Sea Plate against the Eurasian Plate and the consequent collision of the Luzon Arc against Taiwan from the northeastern side. We joined the TAIGER programme and collected the new topographic data in this area by EM-122 swath bathymetric echo sounder on board R/V Marcus G.Langseth during the TAIGER-2009 Leg2 cruise. We also compiled all the available multibeam bathymetric survey data in this area from JAMSTEC fleet cruises and NOAA/NGDC multibeam database.The Ryukyu Trench area south of Miyako and Yaeyama Islands is classified into zonal topographic domains. The northernmost zone is characterised by the distribution of well-developed submarine canyons along the southern coasts. The next is by amphitheatres, slump sediment blocks and their large-scale subsidence. … More The southern zone is by quite complicated topography, such as several escarpments, ridges and troughs and an E-W trending half graben. The southernmost zone is the trench axis area with depth of about 6500. 6600 m, which is characterised by a flat plane. The width of the axial plain is about 40 km of Yaeyama Islands which shows maximum and decreases towards both east and west. However, the topographic features of the trench is unclear on the western side of the Gagua Ridge collision(123°E).One of the across-arc normal faults located off the eastern coast of Ishigaki Island was already studied by multibeam sounding and ROV reconnaissance. Precise analyses of the data revealed an episodic northwestward propagation of the fault, probably due to the arc-parallel extension caused by the rifting of the Okinawa Trough.The observed topographic features suggest that the roll back of the subducting Phippine Sea Plate and the southward retreat of the trench axis is taking place on the eastern side of 123°E due to the oblique subduction, which corresponds to the extension of the western Okinawa Trough. However, on the western side of 123°E, it is unclear whether subduction of Huatung Basin is taking place. It may be possible that Huatung Basin couples with the fore-arc and back-arc areas and that these three areas altogether collides against the Taiwan block. Clear Benioff zone is observed below the fore-arc area on the north of Huatung Basin. However, this might be derived from the West Philippine Basin subducting northwestward obliquely against the Eurasia Plate. Less

从菲律宾海板块向西北俯冲终止以及随之而来的碰撞的角度来看，西南琉球地区是理解弧形海沟-弧-弧后系统对台湾造山运动作用的关键；我们加入了 TAIGER 计划，并通过 EM-122 条带测深回波收集了该地区的新地形数据。 R/V Marcus G.Langseth 在 TAIGER-2009 Leg2 巡航期间使用了 R/V Marcus G.Langseth 上的发声器我们还从 JAMSTEC 舰队巡航和 NOAA/NGDC 多波束数据库中汇编了该区域的所有可用多波束测深数据。八重山群岛被划分为地带性地形域，最北端地区的特点是南部海岸分布着发育良好的海底峡谷。其次是露天剧场、塌陷沉积块及其大规模沉降…… 南部地带地貌较为复杂，有数个陡坡、山脊和槽地以及东西向的半地堑。深度约6500. 6600 m，其特点是平面平坦，轴向平原的宽度约为八重山40公里。岛屿向东、西方向最大，逐渐减小，但在加瓜海岭碰撞西侧（123°E），海沟的地形特征尚不清楚。位于东海岸的跨弧正断层之一。石垣岛的断层已经通过多波束测深和 ROV 勘察进行了研究。对数据的精确分析显示，断层呈间歇性向西北方向传播，这可能是由于裂谷引起的弧形平行延伸所致。观测到的地形特征表明，由于斜向俯冲作用，俯冲菲律宾海板块的后滚和海沟轴线的南退发生在123°E东侧，这对应于冲绳海槽的伸展然而，在东经123°的西侧，尚不清楚华东盆地是否正在发生俯冲，华东盆地可能与冲绳海槽耦合。弧前和弧后区域，并且这三个区域共同碰撞台湾地块，在华东盆地北部的弧前区域下方观察到明显的贝尼奥夫带，但这可能是由西菲律宾盆地俯冲引起的。向西北斜抵欧亚板块。