华南东部白垩纪火山岩盆地构造演化与动力学过程

发布时间：2018-03-30 17:00

本文选题：华南　切入点：白垩纪盆地　出处：《合肥工业大学》2015年硕士论文

【摘要】：华南大陆位于特提斯碰撞构造域和滨太平洋俯冲增生构造域之间。中生代,古太平洋板片向亚洲大陆之下俯冲和印支-华南大陆间的俯冲／碰撞作用诱发了华南大陆内部广泛的陆内变形和岩浆活动。广泛分布的火山岩盆地是探索华南大陆白垩纪构造演化的重要物质记录。这些火山岩盆地中的岩石地层单元由下至上可分为早白垩世火山岩套(Klv)、永康群(K1-2)和金衢群(K2)。本文对这些地层中的夹层火山岩进行了SHRIMP锆石U-Pb和LA-MC-ICPMS锆石U-Pb年代学分析,结果表明：(1)早白垩世火山岩套的形成时代为136-129Ma;(2)永康群可划分为上、下2个火山-沉积组合,下火山-沉积组合包括馆头组和朝川组,其形成于124-112 Ma；上火山-沉积组合以方岩组为代表,其形成于104-91Ma。(3)金衢群沉积于91Ma之后。断层滑动矢量与古构造应力场反演资料表明,华南东部在白垩纪到古近纪时期,盆地经历了三个伸展-挤压旋回的构造演化过程：第一、二旋回分别发生于早白垩世(124-112Ma)和早白垩世晚期-晚白垩世早期(104-91Ma),古构造应力场均以NW-SE伸展和NW-SE挤压的交替出现为典型特征。第三构造旋回发生于晚白垩世-古近纪早期,古构造应力场以N-S伸展和NE-SW挤压为特征。NW-SE伸展事件控制了盆地的初始张开、断陷和沉积物充填,其动力学背景与古太平洋板块俯冲过程中因俯冲板片后撤(roll-back)诱发的弧后扩张作用有关。NW-SE挤压事件导致盆地的构造反转,下白垩统普遍褶皱,并形成区域角度不整合面,其形成与古太平洋构造域俯冲板片的几何学变化或陆缘碰撞的远程效应有关。N-S伸展事件控制了晚白垩世盆地的张开、断陷与沉积充填,与新特提斯构造域板块俯冲诱发的弧后扩张有关; NE-SW挤压事件引发了盆地再一次的构造反转。造成区内盆地的整体抬升和新生代地层的缺失,其动力学成因与新特提斯构造域印度-亚欧大陆碰撞作用相关。华南东部白垩纪盆地伸展-挤压事件的幕式交替记录了古太平洋和新特提斯两大构造域对华南大陆的交替影响和复杂的陆缘板块动力学过程。
[Abstract]:The southern China continent is located between the Tethys collision tectonic domain and the subduction and accretive tectonic domain of the riparian Pacific Ocean. The subduction of paleo-Pacific plate to the Asian continent and the subduction / collision between Indosinian and South China continents induced extensive intra-continental deformation and magmatic activity within the South China continent. The widely distributed volcanic basin is to explore the great South China. The lithostratigraphic units in these volcanic basins can be divided into early Cretaceous volcanic suite Klvan, Yongkang Group K1-2) and Jinqu Group K2. In this paper, the intercalation volcanic rocks in these strata are discussed. SHRIMP zircon U-Pb and LA-MC-ICPMS zircon U-Pb chronology analysis were carried out. The results show that the formation age of the early Cretaceous volcanic suite is 136-129 Majiao 2) the Yongkang Group can be divided into the upper two volcanic-sedimentary assemblages and the lower volcanic-sedimentary assemblage includes the Guantou formation and the Chaochuan formation. It was formed at 124-112 Ma.The Upper Volcanic-Sedimentary assemblage was represented by the calcite formation, which was formed after 91Ma. The fault slip vector and paleotectonic stress field inversion data show that the eastern part of South China occurred during the Cretaceous to Paleogene period. The basin has undergone three tectonic evolution processes of extension-compression cycle: first, The two cycles occurred at 124-112 Ma in the early Cretaceous and 104-91 Ma in the late Cretaceous to the early late late late Cretaceous. The paleotectonic stress fields were characterized by the alternation of NW-SE extension and NW-SE compression. The third tectonic cycle occurred from the late Cretaceous to the early Paleogene. The paleotectonic stress field is characterized by N-S extension and NE-SW compression. NW-SE extensional events control the initial opening of the basin, fault depression and sediment filling. Its dynamic background is related to the back-arc expansion induced by the withdrawal of subduction plates during subduction of the paleo-Pacific plate. NW-SE compressional events lead to the tectonic inversion of the basin, the general folds of the Lower Cretaceous, and the formation of regional angle unconformities. Its formation is related to the geometries of subduction plates in the paleo-Pacific tectonic domain or the remote effects of continental margin collision. The events of N-S extension control the late Cretaceous basin opening, fault depression and sedimentary filling. It is related to the back-arc expansion induced by plate subduction in the Neo-Tethys tectonic domain, and the NE-SW compressional event has triggered another tectonic reversal of the basin, resulting in the whole uplift of the basin and the loss of the Cenozoic strata in the area. Its dynamic genesis is related to the Indo-Eurasian collision in the Neo-Tethys tectonic domain. The extension-compression events of the Cretaceous basin in the eastern part of South China were recorded alternately in the Paleo-Pacific and Neo-Tethys tectonic domains over the Great South China. The alternating influence of the land and the complex dynamics of the continental margin plate.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P542

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