南海北部晚新生代岩浆活动的发育特征与构造意义  

CHARACTERISTICS OF LATE CENOZOIC MAGMATIC ACTIVITIES ON THE NORTHERN MARGIN OF SOUTH CHINA SEA AND THEIR TECTONIC IMPLICATIONS

作　　者：夏少红[1] 范朝焰 孙金龙[1] 曹敬贺 赵芳 万奎元 

机构地区：[1]中国科学院边缘海与大洋地质重点实验室,中国科学院南海海洋研究所,广州510301 [2]中国科学院大学,北京100049

出　　处：《海洋地质与第四纪地质》2017年第6期25-33,共9页Marine Geology & Quaternary Geology

基　　金：中国科学院战略性先导科技专项(XDA13010101);国家自然科学基金(41576041,91328206);广东省自然科学基金(2017A030311015)

摘　　要：南海北部陆缘具有极其独特的岩浆活动特征,其岩浆活动在大陆张裂和破裂期间表现的较为薄弱,而在裂后期尤其是海底扩张停止之后的晚新生代时期却变得极为强烈。通过总结南海北部晚新生代玄武岩浆的岩石学、年代学、地球物理学等方面的研究成果,从发育规模、物质属性、构造模式以及通道特征等方面系统揭示了岩浆活动的发育特征及其隐含的构造意义。结果显示:(1)南海北部晚新生代玄武岩均显示洋岛玄武岩(OIB)的物质属性,且与世界典型热点火山OIB具有相似的同位素分布范围;(2)南海北部海底火山的侵入和喷出体积量与世界典型的大火成岩省具有可对比性;(3)岩石圈伸展过程中所形成的张性断裂可能为后期玄武岩浆的活动提供了良好的通道;(4)沉积地层中所发现的岩脉与岩墙复合体与海底火山活动应该具有相同的岩浆来源;(5)全球和区域地震层析成像结果均显示了一条清晰的深部低速通道,暗示了南海北部晚新生代玄武岩浆活动可能与深部地幔柱存在紧密联系。The northern margin of South China Sea is characterized by unique magmatic activities.They were weak during the period of continental rifting and breakup but intense in the late Cenozoic of post-rifting stage,particularly after the cessation of seafloor spreading.In this paper,studied are the characteristics of magmatic activities in the late Cenozoic including the scale,material properties,tectonic pattern and conduit features by summarizing the previous research results of petrology,chronology and geophysics.Our results show that：（1）The Late Cenozoic basalts on the northern margin of South China Sea is a kind of oceanic island basalts（OIB）,having similar isotopic distribution pattern with the typical hotspot OIB of the world;（2）The volume and scale of the submarine volcanism on the northern margin of South China Sea are comparable to the typical igneous rocks of the world;（3）The tensile faults formed during the extension and rifting of the lithosphere may provide a good conduit for the basaltic magma to move upward;（4）The dyke and dike complexes found in the sedimentary strata have the same magmatic source as the submarine volcanism;（5）Global and regional seismic tomography results show a clear deep low-speed channel,suggesting that the Late Cenozoic basaltic magmatism on the northern margin of South China Sea may be closely related to a deep mantle plume.

关 键 词：玄武岩浆作用 地幔柱 海底火山 南海北部 晚新生代 

分 类 号：P736.1[天文地球—海洋地质]