Tectonic Evolution and Key Geological Issues of the Proto‐South China Sea

Abstract

There are numerous controversies surrounding the tectonic properties and evolution of the Proto-South China Sea (PSCS). By combining data from previously published works with our geological and paleontological observations of the South China Sea (SCS), we propose that the PSCS should be analyzed within two separate contexts: its paleogeographic location and the history of its oceanic crust. With respect to its paleogeographic location, the tectonic properties of the PSCS vary widely from the Triassic to the mid-Late Cretaceous. In the Triassic, the Paleo-Tethys and the Paleo-Pacific Oceans were the major causes of tectonic changes in the SCS, while the PCSC may have been a remnant sea residing upon Tethys or Paleo-Pacific oceanic crust. In the Jurassic, the Meso-Tethys and the Paleo-Pacific oceans joined, creating a PSCS back-arc basin consisting of Meso-Tethys and/or Paleo-Pacific oceanic crust. From the Early Cretaceous to the mid-Late Cretaceous, the Paleo-Pacific Ocean was the main tectonic body affecting the SCS; the PSCS may have been a marginal sea or a back-arc basin with Paleo-Pacific oceanic crust. With respect to its oceanic crust, due to the subduction and retreat of the Paleo-Pacific plate in Southeast Asia at the end of the Late Cretaceous, the SCS probably produced new oceanic crust, which allowed the PSCS to formally emerge. At this time, the PSCS was most likely a combination of a new marginal sea and a remnant sea; its oceanic crust, which eventually subducted and became extinct, consisted of both new oceanic crust and remnant oceanic crust from the Paleo-Pacific Ocean. In the present day, the remnant PSCS oceanic crust is located in the southwestern Nansha Trough.

Crustal structure of the Northeast South China Sea rifted margin

“…These two continental blocks (i.e., Palawan and Southern High) are conjugates and were part of the same terrane before the opening of the South China Sea. This interpretation is supported by geochemistry , plate kinematic (Advokaat and van Hinsbergen, 2024;Cao et al, 2022;Merdith et al, 2021;Müller et al, 2019;Scotese, 2016;Tian et al, 2021;Torsvik et al, 2019;Young et al, 2019), and paleotectonic (Hinz et al, 1991;Holloway, 1981Holloway, , 1982Sibuet et al, 2016;Taylor and Hayes, 1983) reconstructions. As the Palawan Continental Block has been assigned as part of the Luconia Microcontinent (Hall, 2012;Hall and Breitfeld, 2017;Pubellier and Sautter, 2022;Sautter and Pubellier, 2022), it is geologically reasonable to state that so does the SH (Figure 11) (Figure 12b).…”

Construction of the Continental Asia in Phanerozoic: A Review

“…The subduction of the western Pacific plate may begin in the Verkhoyansk-Kolyma Orogen, northeastern Russia, in the early Late Cretaceous (Filatova and Khain, 2008), resulting in the Okhotsk-Chukotka volcanic belt, a subduction-related volcanic province with ages of 89-87 Ma (Tikhomirov et al, 2008), and fold-and-thrust in the Verkhoyansk Mountains in the Late Cretaceous (Gaina et al, 2002). In the south, the subduction of the Pacific plate may cause the formation of the Proto-South China Sea as a back-arc basin in the Cretaceous (Tian et al, 2021). In the Cenozoic, there are three expansion episodes in 65-35 Ma, 32-15 Ma, and the past 5 Ma, respectively, and one compression tectonic event in 15-5 Ma in the Western Pacific, according to comparative analyses of the ages of magnetic anomaly bands (Yin, 2010;Shi and Yan, 2013).…”

The 2014 Northern Thailand Mw 6.1 Earthquake and its Seismogenic Tectonics

“…The collision between the Indian and Eurasian plates started about 45 million years ago, and caused rapid uplifting of the Tibetan plateau which is the largest and highest plateau in the world (Molnar and Tapponnier, 1975;Armijo et al, 1986;England and Houseman, 1986). The collision then resulted in the southward extrusion of the Indochina plate (Molnar and Tapponnier, 1975;Yin, 2000;Chung et al, 2005;Simons et al, 2007;Taylor and Yin, 2009;Styron et al, 2010;Fan et al, 2021;Tian et al, 2021).…”