A rapid shift in the sediment routing system of Lower-Upper Oligocene strata in the Qiongdongnnan Basin (Xisha Trough), Northwest South China Sea
A rapid shift in the sediment routing system of Lower-Upper Oligocene strata in the Qiongdongnnan Basin (Xisha Trough), Northwest South China Sea
复制标题
南海西北琼东南盆地(西沙海槽)下-上渐新世地层沉积物输送系统的快速转变
DOI：
10.1016/j.marpetgeo.2019.03.012
复制
发表时间：
2019-06-01
影响因子：
4.2
通讯作者：
Tong, Chuanxin
中科院分区：
文献类型：
--
作者：
Lei, Chao;Clift, Peter D.;Tong, Chuanxin
渐新世是南海大陆裂解和青藏高原东南缘地表地形变化的时期。在以往的研究中，南海西北部琼东南盆地（QDNB）的渐新统沉积很少被恢复，这限制了对该时期盆地演化的认识。本文对QDNB中渐新世沉积岩进行了碎屑锆石U-Pb定年。下渐新世的U-Pb年龄群体突出了几个竞争源的独特特征，这些竞争源提供了来自盆地和海南岛附近构造高点的物质。QDNB中部上渐新统碎屑锆石U-Pb年龄与越南北方的红河和/或沿岸河流相似。这些沉积物与下渐新世有很大不同。QDNB的这种突变可能意味着其远源沉积最初建立在晚渐新世。重建的渐新世近源-远源沉积物输沙量，有助于了解QDNB沉积物的分布特征，揭示河流水系的演化规律，为南海西北部油气勘探提供依据。
The Oligocene is a period of continental breakup in the South China Sea and of earth surface topographic change in the southeastern margin of the Tibetan Plateau. In previous studies, Oligocene sediment from the Qiongdongnan Basin (QDNB) in the NW South China Sea has seldom been recovered, which limited understanding of basin evolution at this time. Here, we apply detrital zircon U-Pb dating to Oligocene sedimentary rocks from the QDNB. The U-Pb age populations in Lower Oligocene highlight the distinctive signatures of several competing sources providing material from nearby structural highs within the basin and Hainan island. In contrast, detrital zircon U-Pb ages of the Upper Oligocene in the central QDNB shows similarities with the Red River and/or coastal rivers in northern Vietnam. These sediments are significantly different from the Lower Oligocene. This abrupt change in the QDNB may imply that its distal sedimentary sources were initially established in the Late Oligocene. Our reconstruction of sediment discharge from proximal to distal sources in the Oligocene improves understanding of the sediment distribution in the QDNB, which will implicate the river drainage evolution and benefit the petroleum exploration of the Northwest South China Sea.