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陈泽超,林伟,Michel FAURE,Claude LEPVRIER,褚杨,王清晨. 2013. 越南东北部早中生代构造事件的年代学约束. 岩石学报, 29(5): 1825-1840
越南东北部早中生代构造事件的年代学约束
作者单位
陈泽超 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
中国科学院大学, 北京 100049 
林伟 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 
Michel FAURE 法国奥尔良大学地球科学研究所, 奥尔良 45071 
Claude LEPVRIER 法国皮埃尔和玛丽居里大学, 巴黎 UMR7072 
褚杨 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 
王清晨 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 
基金项目:本文受国家973项目(2009CB825008);国家自然科学基金项目(41225009);中国科学院知识创新工程重大项目(KZCX1-YW-15-1)和重大科技项目(2011ZX05008-001)联合资助.
摘要:
      越南东北部-海南岛-粤西南构造带整体上呈NW-SE走向展布于华南板块的南缘,是理解华南构造演化的关键地区。作为印支运动代表性地区的越南东北部地区Song Chay构造带上,下古生界浅变质沉积岩、上古生界至早-中三叠世未变质的沉积盖层中都发育向北东逆冲推覆,韧性变形域表现为NE-SW向的矿物拉伸线理和上部指NE的剪切变形,而脆性变形域则记录了大量NE极性的褶皱和冲断构造。两广交界的云开地体和海南岛地区存在着相同样式的构造变形。关于这期变形的时间,本文通过对野外地层以及所出露不同时期岩体变形特征的综合研究,并结合高质量的锆石U-Pb年代学数据,在越南的东北部厘定为237~228Ma。这期广泛分布于华南板块南缘构造事件的动力学机制同Day Nui Con Voi(大象山)微陆块与华南板块在早中生代的构造拼合事件相关。本文认为华南板块在早三叠世开始沿着越南东北部的Song Chay缝合带俯冲拼合于Day Nui Con Voi微陆块之下,因此在早-中三叠世时期,在作为俯冲盘的华南板块南缘发育一系列的褶皱和逆冲推覆构造,晚三叠世印支造山作用结束。因此,华南板块南缘的越南东北部-海南岛-粤西南构造带被一同卷入早-中三叠世同印支板块的碰撞造山体系之中。
英文摘要:
      The northeastern Vietnam, northeastern Guangxi, southwestern Guangdong and Hainan Island with NW-SE trending all locate in south margin of South China Block (SCB). It is an important region to understanding the tectonic evolution of South China Block. Song Chay belt locates in the northeast region of Vietnam, a NE-SW mineral and stretching lineation,and top-to-the-NE ductile deformation are the main structures and observed both in Early Paleozoic lower metamorphism face strata and Late Paleozoic to Early Mesozoic unmetamorphozed sedimentary rocks. These structural characteristics were coeval with N/NE verging recumbent folds and nappes. Alike for the Song Chay belt, the same Early Mesozoic structural characteristics are also observed in Yunkai terrane, Hainan island and northeast region of Guangxi. All of these deformations occurred in the same tectonic event because of the time and the deformation style are almost the same. To decipher the time of this deformation, we study the structural character of deformed strata and granitic rocks, and analyzed the high quality U-Pb zircon geochronology data, then defined the time of nappes as 237~228Ma. The geodynamic of the tectonic event can be related to the collision between South China Block and Indochina in the Early Mesozoic time. We argue that South China Block subducted beneath to Day Nui Con Voi micro-continental block along Song Chay suture zone in Early Triassic, the south margin of SCB as the subduction plate were developed top to NE thrust and NE verging nappes. This orogeny is over at Late Triassic. Therefore, the northeastern Vietnam, northeastern Guangxi, southwestern Guangdong and Hainan island are belong to the southern margin of SCB and involved in the Indosinian orogenic belt.
关键词:华南板块南缘  Song Chay构造带  逆冲推覆  早中生代  构造演化
投稿时间:2013-02-05  修订日期:2013-04-01
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