鱼山-久米断裂带构造特征及其对中新世以来东海东部构造演化的分隔控制

The tectonic evolution of the East China Sea and its present tectonic framework are influenced by the Yushan-Kume Fault Belt. However, little work has been done on the geometric, kinematic, dynamic and deep structure characteristics of the fault belt. For the purpose of better understanding the transition and accommodation that the Yushan -Kume Fault Belt has played in the tectonic evolution of the East China Sea, in this project, several studied were intended to be conducted, including gravity and magnetic inversion, structural analysis of the seismic reflection profiles, seismic stratigraphic interpretations, balanced cross section analysis, OBS deep seismic sounding and finite element numerical simulation. Based on the above works, the position, distribution and segmentation of the fault belt will be ascertained. 3D shallow structural model and deep crustal and mantle velocity model will be developed. The activity intensities of different segments of the fault will be evaluated quantificationally. The tectonic stress field of the southeastern segment of the fault belt will be explicated. Finally, some previous results including the structural characteristics and evolution processes of the shelf margin, the Ryukyu trench-arc-backarc system and the Taiwan orogenic belt will be taken into account to explicit the separation and control effects that the Yushan-Kume Fault Belt has played during the evolution of the eastern East China Sea since Miocene. And the plate-plate interaction model of the southeastern East China Sea since Miocene will be developed. This study is not only helpful to reconstruct the evolution history of the East Asian continental margin, but can also benefit the exploration and exploitation of the oil and gas and submarine mineral resources.

鱼山-久米断裂带对东海构造演化过程和现今构造格局产生了显著影响，目前对其几何学、运动学、动力学和深部构造特征的研究较少。为了进一步揭示鱼山-久米断裂带在东海构造演化过程中的分隔控制和转换协调作用，本项目拟采用重磁反演计算、二维地震剖面精细构造解释、地震地层学研究、构造平衡剖面分析、OBS 深地震探测、有限元数值模拟等方法，查明鱼山-久米断裂带平面展布特征和分段性，建立断裂带浅部三维结构模型和深部壳-幔速度结构模型，定量评价断裂带活动强度，明确断裂带东南段构造应力场的时空变化特征。结合东海陆架东缘、琉球沟-弧-盆体系、台湾碰撞造山带构造特征和形成演化的研究成果，阐明鱼山-久米断裂带对中新世以来东海东部构造演化的分隔控制作用，建立中新世以来东海东南部板块相互作用模型。本项研究是新生代东亚大陆边缘板块重建的重要环节，对推动我国在东海的油气资源和海底矿产资源勘探开发具有重要的实用价值。

鱼山-久米断裂带对东海构造演化过程和现今构造格局产生了显著影响，对其几何学、运动学、动力学特征进行研究，并揭示其对两侧块体深浅部构造和形成演化过程的分隔控制作用，是开展中国东部大陆边缘板块重建、深入认识新生代西太平洋板块汇聚边缘复杂动力过程的关键环节。本项目基于海底地形、重磁、多道地震、海底地震仪（OBS）等资料的处理和综合解译，对鱼山-久米断裂带构造特征及其在晚新生代东海东部构造演化过程中的分隔控制和转换协调作用进行了研究。结果表明，鱼山-久米断裂带是一条深达上地幔的大断裂，其东段在浅部分支形成多条次级左旋走滑张扭性断层。该断裂带是一条重要的构造转换带，以之为界，冲绳海槽及邻区的构造特征和形成演化过程存在显著差异。在中新世-上新世期间，该构造转换带是一条古转换断层的组成部分，协调了南、北两侧方向相反的俯冲作用（南侧欧亚板块俯冲于菲律宾海板块之下，北侧菲律宾海板块俯冲于欧亚板块之下）。鱼山-久米断裂带以北的冲绳海槽中-北段受控于菲律宾海板块的俯冲，弧后张裂自中中新世延续至今；以南的冲绳海槽南段主要形成于第四纪期间，受台湾碰撞造山作用的显著影响。台湾造山带初始弧-陆碰撞点位于鱼山-久米断裂带附近，随着主造山作用的向西迁移和琉球俯冲带的向西前展，古造山带逐渐塌陷解体，被弧后张裂取代，即“造山带塌陷为弧后张裂开辟道路”。东海陆架外缘和冲绳海槽西坡存在明显的分段性，不同分段之间在地形地貌、基底构造和沉积层结构等方面存在显著差异，体现了弧后张裂过程的非同步性，但仍需结合新的调查成果，对本区更小尺度的分段特征以及更高分辨率的穿时性弧后张裂过程开展进一步研究。本项研究为新生代东亚大陆边缘板块相互作用过程重建提供了新的证据和模式，对推动我国在东海的油气资源和海底矿产资源勘探开发具有重要的实用价值。