南海岩石圈破裂方式与扩张过程的三维物理模拟  

Discussion on the South China Sea Evolution and Lithospheric Breakup through 3D Analogue Modeling

作　　者：孙珍[1] 孙龙涛[1] 周蒂[1] 蔡东升[2] 李绪深[2] 钟志洪[3] 姜建群[4] 樊浩[4] 

机构地区：[1]中国科学院边缘海地质重点实验室、南海海洋研究所,广东广州510301 [2]中国海洋石油有限公司湛江分公司,广东湛江524057 [3]中国海洋石油有限公司深圳分公司技术部,广东广州510240 [4]辽河油田海南油气分公司,辽宁盘锦124010

出　　处：《地球科学（中国地质大学学报）》2009年第3期435-447,共13页Earth Science-Journal of China University of Geosciences

基　　金：国家重点基础研究973计划项目(Nos.2009CB219401,2007CB41170405);中国科学院知识创新工程重要方向项目(No.KZCX3-SW-234-1);国家自然科学基金项目(Nos.40406012,40876026,40576027);中国科学院南海海洋研究所知识创新工程领域前沿项目(No.LYQY200704);中国科学院海洋地质与环境重点实验室开放课题资助项目

摘　　要：南海的形成演化一直是国内外关注的热点之一.为了揭示南海的构造演化过程,分析对比了3组物理模拟实验.实验结果表明,断裂样式和裂谷带的走向与岩石圈的初始热流变结构密切相关.对比模拟结果与陆缘的断层样式,推测在张裂初期,陆坡区比陆架区具有相对热减薄的岩石圈,从而导致不同构造位置上发育不同的裂陷特征.受下地壳和软流圈韧性流动的影响,断层越是靠近扩张区,倾角变得越平缓.实验揭示,破裂首先以点状出现,这些点不断扩大并互相连接形成连续的扩张区.共轭边缘常具有对称的形状,向海盆方向对凹或者对凸.当离散边界附近有刚性块体时,扩张区域的边界会明显受到地块边缘形态的影响.通过模拟实验,推测破裂过程可能以较粘性的方式进行.西北次海盆的发育可能是沿着中-西沙地块北缘深裂陷槽破裂的结果.The evolution of the South China Sea is one of the worldwide hot research spots. In order to investigate its evolution progress of tectonics, we compared three sets of analogue modeling experiments. Modeling experiments suggest that the fault patterns and orientation change of the rift zone were strongly related to the thermal situation and rheological stratification of the lithosphere. Comparing the modeling results with the fault patterns on the conjugate continental margin, we conjectured that the slope area might have born relatively hotter and thinner lithosphere than shelf area from the beginning of rifting. Due to the stretching and mantle upwelling associated with the regional extension, the initial rheolugical stratification was changed and therefore the rifting pattern from shelf to slope. Affected by the ductile flow of lower crust and asthenosphere, the faults became flattened, especially close to the breakup area. In the experiments, breakup developed first at isolated points, which grew and coalesced to become a single spreading area. The conjugate boundaries were either all concave or all convex. When there was a rigid massif located at the divergent boundary, the northern and southern areas of the massif thinned rapidly and developed into two deep troughs, which may finally evolve into spreading centers. The shape of the massif controls the orientation and boundary shape of the spreading area. It＇s supposed that the crustal breakup may go in more viscous style, and the NW sub sea basin may develop along the northern trough of the Zhongsha-Xisha massif.

关 键 词：南海 破裂方式 形成演化 三维物理模拟 

分 类 号：P736[天文地球—海洋地质]