弧前盆地的沉积和构造特征  

Sedimentary and Structural Characteristics of Forearc Basins

作　　者：谭毅滢 肖文交[3,1,2] 宋东方 Tan Yiying;Xiao Wenjiao;Song Dongfang(State Key Laboratory of Lithospheric Evolution,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China;Xinjiang Research Center for Mineral Resources,Xinjiang Institute of Ecology and Geography,Chinese Academy of Sciences,Urumqi 830011,China)

机构地区：[1]中国科学院地质与地球物理研究所岩石圈演化国家重点实验室,北京100029 [2]中国科学院大学地球与行星科学学院,北京100049 [3]中国科学院新疆生态与地理研究所新疆矿产资源研究中心,新疆乌鲁木齐830011

出　　处：《地球科学》2024年第7期2539-2551,共13页Earth Science

基　　金：国家自然科学基金项目(No.42488201).

摘　　要：汇聚板块边缘的沉积盆地是造山带研究的重要对象,其中弧前盆地位于弧前区域靠近岛弧一侧,更易在造山过程中被保留下来,保存造山带结构和演化的信息.本文以研究较为充分的新生代弧前盆地为例,详述了弧前盆地的大地构造位置、形成机制、沉积、物源和构造特征,为古老造山带研究中弧前盆地的识别提供依据.弧前盆地位于岛弧和海沟外坡之间,可以形成于伸展或挤压环境中,前者由伸展正断层形成地堑式盆地,后者由增生楔逆冲构造形成挤压盆地.弧前盆地发育多种类型的沉积,其中洋内弧以半深海-深海相沉积为主,大陆弧则涵盖陆相-海陆交互相-海相等多种沉积相,总体呈现粒度从边缘向中心变细、从下往上变粗的沉积序列.陆源碎屑主要来源于相邻岛弧和增生楔,通过河流、海底峡谷和海底滑坡等方式进入盆地.洋中脊、海山、洋底高原和大洋破碎带俯冲都能不同程度地影响俯冲带结构,造成弧前盆地的反转、抬升剥蚀、沉积间断、物源区变化以及沉积环境的改变.弧前盆地的沉积过程复杂,难以用单一模型简单概括,在应用弧前盆地对造山带进行分析时,应结合多学科资料对地质记录进行综合分析.Sedimentary basins are prominent in convergent margin studies.Located near the volcanic arc in the forearc region,the forearc basin is relatively well-preserved after intense orogeny,with records of intact information about orogenic processes.This paper illustrates the tectonic setting,formation mechanism,provenance,and sedimentary-structural characteristics of the forearc basins exemplified by well-studied Cenozoic examples.Forearc basins are located between the volcanic arc and the trench-slope break.It can be formed in an extensional environment where normal fault forms a half-graben basin,or in a compressional environment where thrusts of the accretionary wedge serve as a dam to pond sediments.All kinds of sedimentary facies can be developed in the forearc basin located in a continental arc,while hemipelagic-pelagic facies are dominant in that located in an intra-oceanic arc.Terrigenous debris is mainly derived from the proximal volcanic arc and accretionary wedge and enters the basin through rivers,submarine canyons,and collapse.Sediments in the forearc basin usually grow thicker from the basin margin to the center and from the bottom to the top.Subduction of mid-ocean ridge,seamount,oceanic plateau,and fracture zone could affect the structure of subduction zones to various degrees,leading to inversion,exhumation,sedimentary hiatus,sedimentary provenance changing,and depositional environment changing of the forearc basin.The development of the forearc basin is difficult to be summarized by a single model.Thus,when forearc basin is applied to orogeny analysis,multi-disciplinary data should be considered in a comprehensive analysis of basin geological records.

关 键 词：俯冲带 弧前盆地 沉积特征 构造特征 造山带 构造地质学 

分 类 号：P542[天文地球—构造地质学] P588.2[天文地球—地质学]