刘心哲^1,2, 陈文文³, 邢军辉^1,2, 吴晓阳^1,2, 安隆^1,2, 张浩^1,2, 彭树聪^1,2
1.海底科学与探测技术教育部重点实验室, 山东 青岛 266100;2.中国海洋大学海洋地球科学学院, 山东 青岛 266100;3.中国海洋大学学报(英文版)编辑部, 山东 青岛 266100

摘要:
以南桑威奇俯冲带为例，根据EGM2008超高阶地球重力场模型、卫星重力数据为基础，利用移去-恢复原理计算了研究区大地水准面，实现了研究区不同场源深度大地水准面异常信息的分离，根据Runcorn模型计算了研究区小尺度地幔对流应力场，并结合天然地震空间展布和前人研究成果，对俯冲带结构特征与地幔对流模式进行了探讨。结果表明：南桑威奇俯冲带具有俯冲倾角较大、地震震级较低、弧前侵蚀明显等典型的马里亚纳型俯冲带特征，俯冲带南北部俯冲深度存在明显差异，中段偏北俯冲深度可达500 km；受到软流圈与上地幔上部物质密度差异的控制，东斯科舍海脊下存在沿海脊轴向南流动强地幔流；俯冲带结构与小尺度地幔对流应力场具有很强的相关性。本研究对于搞清南桑威奇俯冲带深部构造特征，理解俯冲运动、地幔对流方向及其动力控制机制提供了新的研究思路和方法。
关键词:南桑威奇俯冲带EGM2008地球重力场模型大地水准面异常地幔对流
DOI：10.11759/hykx20181019001
分类号:P738.2
基金项目:国家自然科学基金项目（41606044）；国家科技重大专项项目（2016ZX05027-002）

Analysis of geoid anomalies and mantle convection features in the South Sandwich subduction zone
LIU Xin-zhe^1,2, CHEN Wen-wen³, XING Jun-hui^1,2, WU Xiao-yang^1,2, AN Long^1,2, ZHANG Hao^1,2, PENG Shu-cong^1,2
1.Key Laboratory of Submarine Geosciences and Prospecting Techniques, Ministry of Education, Qingdao 266100, China;2.College of Marine Geosciences, Ocean University of China, Qingdao 266100, China;3.Editorial Office of Journal of Ocean University of China, Qingdao 266100, China
Abstract:
In this paper, the South Sandwich subduction zone is investigated as an example for applications involving gravity anomalies. Based on the EGM2008 ultra-high-order gravity field model, satellite gravity data, and the remove-restore method, we calculated the geoids and the separation of geoid anomalies at different field source depths. Then, we calculated the stress field from small-scale mantle convection based on the Runcorn model. Finally, we obtained a comprehensive understanding of the structural characteristics and the mantle convection model of the subduction zone based on the natural seismic distribution and previous research results. The results show that the South Sandwich subduction zone is a typical Mariana type with a large subduction dip angle, low seismic magnitude, and obvious fore-arc erosion. The subduction depth differs strongly from south to north, with the maximum subduction depth of 500 km occurring in the middle-northern part. Controlled by the density difference between the asthenosphere and upper mantle, a strong southward axial mantle flow occurs beneath the East Scotia Ridge. The structure of the subduction zone is strongly correlated with the stress field from small-scale mantle convection. The research results presented in this paper provide a new research approach and method for understanding the deep tectonic characteristics of the South Sandwich subduction zone, the subduction movement, the mantle convective direction, and its dynamic control mechanism.
Key words:the South Sandwich subduction zoneEGM2008 gravity field modelgeoid anomalymantle convection





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