Denudation history of South China block and sediment supply to northern margin of the South China Sea
Denudation history of South China block and sediment supply to northern margin of the South China Sea
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DOI：
10.1007/s12583-009-0006-3
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发表时间：
2009-04
影响因子：
3.3
通讯作者：
Yi Yan;Xiaoqiong Hu;G. Lin;B. Xia;Xiaoyong Li;R. Patel
中科院分区：
文献类型：
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作者：
Yi Yan;Xiaoqiong Hu;G. Lin;B. Xia;Xiaoyong Li;R. Patel
通过磷灰石裂变径迹（AFT）分析，对南海北方边缘新生代构造地貌演化和沉积物供给进行了定量研究。从华南陆块沿海到内陆共采集了17个花岗岩样品。AFT年龄与样品位置的关系曲线显示，AFT年龄总体上呈远离海岸的趋势，这意味着在破碎后的演化过程中，南海内陆的侵蚀和沉积作用更为持久。从模拟的冷却历史中推断出两个阶段的快速侵蚀过程，即早第三纪和中中新世。沿着海岸（70 ~ 60 Ma）和内陆（50 ~ 30 Ma）分别记录了早第三纪的第一次快速冷却和剥蚀。这表明早第三纪期间南海北方边缘发生了初始的局部侵蚀和沉积。沿海沿着的快速侵蚀自约1940年以来就停止了。50马，而它一直持续到约。30 Ma，表明侵蚀作用由局部海岸带向大陆内部转移，北方边缘统一沉降，形成了大陆边缘南倾的地形。华南陆块的热停滞期是自公元前以来的。30 Ma必须确定北方边缘与向南发生的活跃裂谷和伸展作用动态断开的时间。珠江口盆地晚渐新世（约1000年）较低的侵蚀速率与较高的沉积速率不一致。25 Ma）。这表明，盆地内沉积作用的增加不是由于华南地块花岗岩带的侵蚀作用，而是与青藏高原东缘隆升和南海扩张轴南跳有关的古珠江水系向西传播的结果。中中新世的第二次侵蚀加速率（约。14 Ma）的冷却可能与青藏高原隆升的远距离效应或东亚季风的增强有关。
On the basis of apatite fission track (AFT) analyses, this article aims to provide a quantitative overview of Cenozoic morphotectonic evolution and sediment supply to the northern margin of the South China Sea (SCS). Seventeen granite samples were collected from the coast to the inland of the South China block. Plots of AFT age against sample location with respect to the coastline show a general trend of youngling age away from the coast, which implies more prolonged erosion and sediment contribution at the inland of the South China Sea during post break-up evolution. Two-stage fast erosion process, Early Tertiary and Middle Miocene, is deduced from simulated cooling histories. The first fast cooling and denudation during Early Tertiary are recorded by the samples along the coast (between 70 and 60 Ma) and the inland (between 50 and 30 Ma), respectively. This suggests initial local erosion and deposition in the northern margin of the SCS during Early Tertiary. Fast erosion along the coast ceased since ca. 50 Ma, while it had lasted until ca. 30 Ma inland, indicating that the erosion was transferred from the local coastal zone initially toward the continental interior with unified subsidence of the northern margin, which resulted in the formation of a south-dipping topography of the continental margin. The thermal stasis in the South China block since ca. 30 Ma must define the time at which the northern margin became dynamically disconnected from the active rifting and stretching that was taking place to the south. The lower erosion rate is inconsistent with higher sedimentary rate in the Pearl River Mouth basin during Late Oligocene (ca. 25 Ma). This indicates that the increased sedimentation in the basin is not due to the erosion of the granite belt of the South China block, but perhaps points to the westward propagation of the paleo-Pearl River drainage related to the uplift of the eastern margin of Tibet plateau and southward jumping of spreading axis of the South China Sea. The second erosion acceleration rate of the Middle Miocene (ca. 14 Ma) cooling could have been linked to the long-distance effect of uplift of the Tibet plateau or due to the enhanced East Asian monsoon.