The North Pacific subtropical gyre (NPSG) plays a major role in present global ocean circulation. At times, the gyre has coursed through the South China Sea, but its role in the evolutionary development of that Sea remains uncertain. This work systematically describes a major shift in NPSG paleo-circulation evident from sedimentary features observed in seismic and bathymetric data. These data outline two contourite depositional systems—a buried one formed in the late Miocene, and a latest Miocene to present-day system. The two are divided by a prominent regional discontinuity that represents a major shift in paleo-circulation during the latest Miocene (~ 6.5 Ma). The shift coincides with the further restriction of the South China Sea with respect to the North Pacific due to the formation of the Luzon Strait as a consequence of further northwest movement of the Philippine Sea plate. Before that restriction, data indicate vigorous NPSG circulation in the South China Sea. Semi-closure, however, established a new oceanographic circulation regime in the latest Miocene. This work demonstrates the significant role of recent plate tectonics, gateway development, and marginal seas in the establishment of modern global ocean circulation.

北太平洋副热带环流（NPSG）在目前的全球海洋环流中发挥着重要作用。有时，环流穿过南海，但它在南海演化发展中的作用仍不确定。这项工作系统地描述了从地震和测深数据中观察到的沉积特征明显的 NPSG 古环流的重大转变。这些数据概述了两个等高岩沉积系统——一个形成于晚中新世的埋藏系统，以及一个最新的中新世至今的系统。两者被一个突出的区域不连续性分开，这代表了最近中新世（~6.5 Ma）古环流的重大转变。由于菲律宾海板块进一步向西北移动，吕宋海峡的形成，导致南海对北太平洋的进一步限制，这一转变恰逢其时。在此限制之前，数据表明南海有强烈的 NPSG 环流。然而，半封闭在最近的中新世建立了一个新的海洋环流制度。这项工作证明了最近的板块构造、门户发育和边缘海在建立现代全球海洋环流中的重要作用。