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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

从菲律宾海板块向欧亚板块俯冲的西北终止和吕宋弧从东北侧向台湾的碰撞的观点出发，琉球西南部地区是理解弧形海沟-弧-弧后体系对台湾造山作用的关键。我们加入了TAIGER计划，并在TAIGER-2009第二航段巡航期间，通过Marcus G.Langseth号R/V上的EM-122条带测深回声测深仪收集了该区域的新地形数据。利用JAMSTEC船队和NOAA/NGDC多波束数据库中的多波束测深资料，将宫古岛和八重山岛以南的琉球海沟划分为带状地形域。最北部区域的特点是沿着南部海岸分布着发育良好的海底峡谷。其次是圆形剧场、滑塌沉积块体及其大规模沉降作用。 ...更多信息南部地区地形复杂，有多个陡崖、山脊和海槽，以及一个东西走向的半地堑。最南带为海沟轴线区，深度约6500。6600米，其特点是平面。轴向平原的宽度约为八重山群岛的40公里，最大，向东和向西逐渐减小。然而，加瓜海岭碰撞西侧（123°E）海沟的地形特征尚不清楚，位于石垣岛东海岸外的一条跨弧正断层已被多波束测深和地震勘探研究。精确分析表明，该断裂呈幕式向北西扩展，可能是由于冲绳海槽的裂谷作用引起的弧平行伸展.观测到的地形特征表明，俯冲的菲宾海板块的回滚和海沟轴的南退缩是由于斜向俯冲作用在123°E东侧发生的，与冲绳海槽西部的延伸相对应。然而，在123°E西侧，目前还不清楚是否正在发生俯冲的花东盆地。花东盆地可能与弧前、弧后地区耦合，共同碰撞台湾陆块。华南盆地北部弧前区以下存在明显的贝尼奥夫带。然而，这可能是由于西菲律宾盆地向西北斜向俯冲于欧亚板块。少