摘要
古特提斯洋的形成与演化导致了冈瓦纳大陆北缘多个陆块的裂解分离、向北漂移并最终拼贴到亚洲大陆的南侧,该洋盆的闭合形成了多条蛇绿岩带。印支造山带作为古特提斯造山带的一部分,记录了古特提斯洋的演化历史,但其洋盆位置、俯冲极性等关键科学问题仍存在争议。回答上述问题的关键在于厘定中国−越南(中越)边境地区的八布−高平构造带的构造属性和越北地块的构造归属,即八布−高平构造带是否代表开阔洋盆的缝合带,以及越北地块是华南地块的组成部分还是一个独立的小陆块。因此,通过搜集华南地块西南缘南盘江盆地、中越边境地区的八布−高平构造带和越北地块3个构造单元中的31个碎屑岩锆石年龄数据和越北地块斋江岩体的岩浆结晶−继承锆石的年龄数据,进行了锆石年龄分布直方图和概率曲线谱峰对比。研究结果发现,这些样品多具有270~250 Ma、460~420 Ma、1000~900 Ma的年龄谱峰,另外年龄数据在1800 Ma左右以及2500 Ma左右也相对集中,这体现了3个构造单元物源存在较好的一致性。结合南盘江盆地和越北地块晚古生代—早中生代地层对比结果,以及同时期动物区系的相似性,研究推测自泥盆纪以来的伸展作用导致了八布−高平构造带在二叠纪时发育裂谷、深水沉积,甚至演化至初始洋盆;然而由于其扩张幅度有限,未发育成广阔的大洋,也未完全裂解进而阻断了越北地块和南盘江盆地的联系。越北地块是华南地块的重要组成部分,古特提斯开阔洋盆应位于越北地块南侧区域。研究成果为印支造山带中大地构造单元划分提供了证据和论证,对理解中越边境地区印支造山作用和过程具有一定程度的指导价值。
[Objective]During the opening and closing of the Paleo-Tethys ocean,multiple continental blocks rifted from the northern margin of Gondwana,drifted northward,and eventually merged with the southern boundary of the Asian continent,forming multiple serpentinite belts.As part of the Paleo-Tethys orogenic belt,the Indosinian orogenic belt records the evolution history of the Paleo-Tethys ocean;however,key scientific issues,such as the location of the ocean basin and the subduction polarity,remain controversial.The keys to addressing these questions lie in defining the structural characteristics of the Babu–Cao Bang tectonic belt along the Sino-Vietnamese border and clarifying the tectonic affinity of the North Vietnam terrane.Specifically,it has to be determined,whether the Babu–Cao Bang tectonic belt represents a suture zone of a wide ocean basin,and whether the North Vietnam terrane is a component of the South China block or an independent micro-continental block.[Methods]In order to clarify these two questions,detrital zircon age data were collected from 31 sedimentary rocks in three tectonic units including the Nanpanjiang basin along the southwestern margin of the South China block,the Babu-Cao Bang tectonic belt,and the North Vietnam terrane.Furthermore,age data of inherited igneous zircon from the Song Chay massif in the North Vietnam terrane were obtained.The zircon age distribution histograms and probability curve peaks were compared within these three tectonic units.[Results]It was found that the age spectra of these samples mostly have peaks at 270-250 Ma,460-420 Ma,and 1000-900 Ma.In addition,the age data are relatively concentrated around 1800 Ma and 2500 Ma,which reflects good consistency in the provenance of the three tectonic units.[Conclusion]Based on the stratigraphic correlation between the Nanpanjiang basin and the North Vietnam terrane from the late Paleozoic to the early Mesozoic and the faunal similarities during the same period,this study speculates that an extensional event led to the development of rifts,deep-water sediments,and even oceanic crust in the Babu-Cao Bang tectonic belt during the Permian.However,due to its limited extensional magnitude,this rift failed to evolve into a mature oceanic basin,preserving the tectonic connection between the North Vietnam terrane and the Nanpanjiang basin.The North Vietnam terrane is an important component of the South China block,and the open basin of the Paleo-Tethys ocean should have been located to the south of the North Vietnam terrane.[Significance]This study provides evidence for the division of tectonic units in the Indosinian orogenic belt,and guides our understanding of Indosinian orogenic processes in the Sino-Vietnamese border area.
作者
夏磊
夏文静
卫巍
宋超
王印
刘飞
XIA Lei;XIA Wenjing;WEI Wei;SONG Chao;WANG Yin;LIU Fei(School of Architectural and Civil Engineering,Kunming University,Kunming 650214,Yunnan,China;College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China;School of Humanities and Social Sciences(School of Public Administration),Beihang University,Beijing 100037,China;State Key Laboratory of Lithospheric and Environmental Coevolution,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;Geosteering&Logging Research Institute,Sinopec Matrix Corporation,Qingdao 266071,Shandong,China;Wuhan Center,China Geological Survey(Geosciences Innovation Center of Central South China),Wuhan 430205,Hubei,China;Research Center for Petrogenesis and Mineralization of Granitoid Rocks,China Geological Survey,Wuhan 430205,Hubei,China)
出处
《地质力学学报》
北大核心
2025年第4期576-588,共13页
Journal of Geomechanics
基金
国家自然科学基金项目(92355302)
中国地质调查局地质调查项目(DD20160201-07)
云南省基础研究计划项目(202401CF070004)
云南省地方本科高校基础研究联合专项项目(202301BA070001-007)。
关键词
南盘江盆地
八布−高平构造带
越北地块
碎屑锆石年龄
印支造山带
古特提斯洋
Nanpanjiang basin
Babu–Cao Bang tectonic belt
North Vietnam terrane
detrital zircon age
Indosinian orogenic belt
Paleo-Tethys ocean
作者简介
第一作者:夏磊(1989-),男,助理研究员,主要从事沉积大地构造学研究。Email:xialei@kmu.edu.cn;通信作者:卫巍(1983-),男,副研究员,主要从事构造地质学研究。Email:weiweigeo@mail.iggcas.ac.cn。
