| 南海西南部万安盆地新生代沉降分析及构造意义 |
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| 作者姓名： | 王蓓羽 张健 艾依飞 |
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| 作者单位： | 中国科学院大学地球与行星科学学院 中国科学院计算地球动力学重点实验室, 北京 100049 |
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| 基金项目： | 中国科学院战略性先导科技专项（XDB42020104）、国家自然科学基金重点项目（91858212）和国家自然科学基金（41906056，U1701245）资助 |
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| 摘 要： | 南海盆地位处特提斯、环太平洋和古亚洲三大构造域交汇部，其西南部代表性万安盆地新生代地层发育齐全，但前人对其构造沉降及伸展机制研究比较薄弱，制约了人们对南海扩张和盆地演化的理解。基于构造格局和地层层序等区域地质资料，利用回剥法模拟万安盆地的构造演化史，并通过McKenzie纯剪切拉伸模型反复调整拉张因子拟合构造沉降史，得到万安盆地的伸展因子与伸展速度，最终通过岩石圈的热传导方程求取基底热流。研究结果表明：南海扩张、洋脊跳跃和西南次海盆扩张的共同作用控制万安盆地的沉降、伸展和热异常；万安盆地具有独特的时空演化特征，即沉降作用受断裂带左行和右行活动的影响，整体上具有V型转折特性，而伸展作用以“早东西、后南北”为主要特点；伸展和热异常均受构造活动的影响，呈现出以断裂带为异常轴、向两侧以不同的速率逐渐减弱的特征。
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| 关 键 词： | 万安盆地 沉降速率 伸展速度 基底热流 |
| 收稿时间： | 2018-11-15 |
| 修稿时间： | 2019-05-20 |
Analysis of tectonic evolution characteristics of Wan'an Basin in the southwest of the South China Sea |
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| Authors: | WANG Beiyu ZHANG Jian AI Yifei |
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| Institution: | Key Laboratory of Computational Geodynamics of CAS, College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China |
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| Abstract: | The South China Sea Basin is located at the junction of Tethys, Pacific margin, and paleo-Asia tectonic domains. The representative Wan'an Basin in the southwest of the South China Sea Basin has the well-developed Cenozoic strata, but the underappreciated expansion and evolution remains because of a limited understanding of tectonic subsidence and extension mechanism of the basins. Based on the regional geological data, including structural style and stratigraphic sequence, the tectonic evolution history of Wan'an Basin is simulated by utilizing the backstripping method, and the extension factor and extension velocity of Wan'an Basin are obtained after fitting the structural subsidence history through an iterative adjustment of the tensile factor in the McKenzie pure shear tensile model. Furthermore, the heat transfer equation of the lithosphere is used to determine the heat flow of the substrate. The results are given as follows. 1) It is the combined action of the South China Sea expansion, the ridge jump, and the southwest sub-basin expansion that control the sedimentation, extension, and thermal anomalies in Wan'an Basin. 2) Wan'an Basin has unique characteristics of space-time evolution that the left and right rotations of the fracture zone affect the sedimentation which presents a V-shaped transition and that “early east and west, then north and south” is the mainly feature of the extension. 3) Due to the tectonic activity, the extension and thermal anomalies in the basin gradually decline in the directions from the fault to the both sides at different rates. |
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| Keywords: | Wan'an Basin sedimentation rate stretch rate basement heat flow |
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