南海在距今34 Ma之前的始新世从陆地变为海洋，古水深不断加深，至距今24 Ma之前的中新世/渐新世之交，由于T60构造运动，南海海盆整体进入深海环境。但是，自中新世以来随着吕宋岛弧向欧亚板块碰撞，南海海盆的半封闭程度在距今10.0、6.5、3.0和1.2 Ma之前加剧，导致南海深部海水只能来自巴士海峡海槛深度2600 m以浅的太平洋。此后，巴士海峡两侧的南海与太平洋深部海水交换，由于全球海平面变化，呈现冰期/间冰期模式。
The present-day South China Sea (SCS) was evolved from land to sea in the Eocene 34 million years ago, and its paleo-water was very deep. At the turn of the Miocene/Oligocene, 24 million years ago, due to the T60 tectonic movement, the entire SCS basin became a deep-sea environment. Since the Miocene, 10.0, 6.5 and 1.2 million years ago, along with the collision of the Luzon island arc with the Eurasian plate, the semi-closed degree of the SCS basin increased, so that the SCS deep-water could only come from the Pacific above the sill depth (~2600 m) of the Bashi Strait. After that, due to the global sea level change, the deep-water exchange between the SCS and the Pacific on both sides of the Bashi Strait displayed the glacial/interglacial mode.
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