Taixinan Basin Explained

The Taixinan Basin, also called the Tainan Basin, and sometimes rendered literally as Southwest Taiwan Basin or Southwestern Taiwan Basin is a basin located in the southern Taiwan Strait and the northeastern South China Sea.^[1]

Location

The Taixinan Basin is in the southern Taiwan Strait and the northeastern South China Sea. It is bordered by the Penghu Uplift in the north, the Dongsha Uplift in the southwest, and the South China Sea basin in the south. It is separated from the Zhujiangkou Basin by the Dongsha Uplift. In the northeast, it stretches inland onto the southwest Taiwan Island.^[2]

Evolution

The Taixinan Basin is located on the continental shelf, on the margin of the continental crust. Its tectonic evolution can be divided in to three periods. The first period was from Paleocene to Oligocene. In the early Paleocene period, the Taixinan Basin experienced the effects of rifting which eventually caused the formation of the basin. The tensile stress field was in the NE-SW direction. Many normal faults developed during this period. The second period began at the end of Oligocene. During this period, the Taixinan Basin experienced the effects of compression. Part of the early normal faults underwent tectonic inversion leading to the development of reverse faults and related folds. The third period started during Miocene with thermal subsidence occurring. In the later Miocene, the South China Sea basin halted its expansion in a period where the sediment layers were horizontal and not controlled by the effects of faulting.^{[3] [4] [5]}

Topography

The Taixinan Basin is in the direction of NE, with a length of about 400 km, average width of 150 km, and an area of more than 60000 km².

Within the Taixinan Basin, there are two depressions in the north and the south, separated by an uplift in the NE direction. The thickness of the Cenozoic sediments in the depressions can reach 8000 m, increasing from west to east. In the eastern part of the basin, the thickness of the sediments can reach 7000 m offshore Kaohsiung.

Onshore, on the southwest Taiwan Island, there is a distribution of normal faults of Paleogene.^[6]

Notes and References

1. "台西南盆地和北港隆起的中生界及其沉积环境" ("The Mesozoic and its sedimentary environment in the Taixinan Basin and Beigang Uplift") by 周蒂
2. "利用重力資料估算台灣海峽之莫霍面深度" ("Using gravity data to estimate the depth of the Moho in the Taiwan Strait") by 史旻弘
3. "台西南盆地新生代主要断裂发育特征" ("Development characteristics of main faults in the Cenozoic era of the Taixinan Basin") by 丁巍伟, 王渝明, 陈汉林, 杨树锋, and 吴能有
4. "南海北部深水盆地沉积－构造的差异性及其油气意义" ("Sediment-structural differences in deep-water basins in the northern South China Sea and their oil and gas significance") by 吕宝凤 and 袁亚娟
5. "南海盆地生物礁形成条件及发育趋势" ("The formation conditions and development trend of reefs in the South China Sea Basin") by 魏喜, 祝永军, 尹继红, 陈亦寒, and 刘东齐
6. "以中尺度反射震测法研究屯子脚断层活动机制及构造上的意义" ("Research on Tunzijiao Fault Activity Mechanisms and Tectonic Significance by Mesoscale Reflection Seismic Method") by 李奕亨