白垩纪—古近纪南海北缘盆地构造特征研究

发布时间：2019-01-30 13:08

【摘要】：南海北缘白垩纪以来的构造特征以挤压和拉张并存，并在此背景下发育出众多的白垩纪-第三纪盆地。这些盆地的演化过程与太平洋板块、欧亚板块的运动情况关系密切，还可能与古南海-南海的演化存在重要联系。本文选取南海北缘中新生代盆地为研究对象，力图通过盆地在中生代之交的构造演化特征来反映南海北缘的构造属性和演化规律。通过对盆地沉积特征、火山岩岩石学特征及盆地构造过程的分析和对比，得出了以下的结论：（1）南海北缘在白垩纪存在一条代表古南海俯冲的陆缘弧，，凡保留有白垩纪火山-沉积记录的南海北缘盆地均表现出与陆缘弧的关联，表明研究区具有一个囊括众多盆地、总宽超过600km的安第斯型陆缘弧体系，体系的展布以南北方向为主。（2）陆缘弧体系内部发展史存在差异，乐东、茂名、三水盆地等近弧区在白垩纪大部分时间内均表现出与陆缘弧压性环境紧密相关的岩浆、沉积或构造特征；而在以衡阳盆地、丹霞-南雄盆地和河源盆地为代表的宽阔弧后带，则在晚白垩世初期普遍显现伸展拉张的地质特征，属于陆缘弧体系的弧后裂谷环境，其主导因素恐与古南海俯冲带后撤、弧后软流圈地幔上涌有关。（3）三水盆地新生代热点式火山喷发拉开现代南海威尔逊旋回的序幕，保存有新生代地质记录的三水盆地、河源盆地、茂名盆地、乐东盆地、珠江口盆地均以稳定的被动陆缘沉积为基本特征，表明古南海的活动陆缘背景完全易位于现代南海的被动陆缘背景。限于目前的研究条件，形成上述重大构造转换的时代界线尚难界定。
[Abstract]:The tectonic features of the northern margin of the South China Sea since Cretaceous coexist with compression and extension, and many Cretaceous-Tertiary basins have been developed under this background. The evolution process of these basins is closely related to the movement of the Pacific plate and Eurasian plate, and may also be related to the evolution of the ancient South China Sea and the South China Sea. In this paper, the Meso-Cenozoic basins in the northern margin of the South China Sea are selected as the research objects, and the tectonic properties and evolution rules of the northern margin of the South China Sea are reflected by the tectonic evolution characteristics of the basins at the intersection of the Mesozoic. Based on the analysis and comparison of the sedimentary characteristics of the basin, the petrological characteristics of volcanic rocks and the tectonic process of the basin, the following conclusions have been drawn: (1) there was a continental margin arc representing the subduction of the ancient South China Sea in the Cretaceous period in the northern margin of the South China Sea. All the basins in the northern margin of the South China Sea with Cretaceous volcano-sedimentary records are associated with the continental margin arc, indicating that the study area has an Andean continental margin arc system with a total width of more than 600km, covering many basins. The distribution of the system is mainly in the north-south direction. (2) there are differences in the internal history of the continental margin arc system. During most of the Cretaceous period, the near-arc areas of the Ledong, Maoming and Sanshui basins showed magmatic, sedimentary or structural characteristics closely related to the continental margin arc pressure environment; In the broad back-arc belt represented by Hengyang basin, Danxia Nanxiong basin and Heyuan basin, extensional and extensional geological characteristics were generally observed in the early stage of the late Cretaceous, which belongs to the back-arc rift environment of the continental margin arc system. The main factors may be related to the retreat of the subduction zone and the upwelling of the mantle in the back-arc asthenosphere in the ancient South China Sea. (3) the Cenozoic hot volcanic eruption in Sanshui basin opens the beginning of Wilson cycle in the modern South China Sea, and the Sanshui basin, Heyuan basin, Maoming basin and Ledong basin, which have the Cenozoic geological records, are preserved. The basic characteristics of the Pearl River Estuary basin are stable passive continental margin deposition, which indicates that the active continental margin background of the ancient South China Sea is easily located in the passive margin background of the modern South China Sea. Limited to the current research conditions, it is difficult to define the time boundary of the formation of the above major structural transformation.
【学位授予单位】：中国地质大学（北京）
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P736.1

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