Tectonic units and proto‐basin of the East China Sea Shelf Basin: correlation to Mesozoic subduction of the Palaeo‐Pacific Plate

Abstract

AbstractThe East China Sea Shelf Basin (ECSSB) is a typical Meso‐Cenozoic superimposed basin characterized by different tectonic frameworks, suffering multi‐stage tectonism (e.g. the Indosinian, the Yanshanian and the Himalayan) since the Mesozoic. The Mesozoic ECSSB is a key place to our understanding of the tectonic evolution and dynamic mechanism in eastern South China and the subduction of the Izanagi Plate. Based on geological and geophysical results acquired over the last 10 years, this paper provides a summary of the distribution of Mesozoic strata, ascertains boundaries of the Mesozoic basin and proposes the division of the Mesozoic tectonic units in the ECSSB. The Mesozoic ECSSB was subdivided into the Western Fault Depression (WFD) characterized by dispersed Cretaceous half‐grabens and the East Depression (ED) characterized by depressions at the early stage and grabens at the later stage. The WFD is composed of half‐grabens formed under transtension, and the ED is composed of depression zones on the pre‐Mesozoic basement under regional compression, indicating different dynamic mechanisms from the Cenozoic basins. Formation of the Mesozoic tectonic framework was controlled by the collision, compression and subduction of the Izanagi Plate and the Pacific Plate and also affected by the Indian Plate at a later stage. By comparison, this paper preliminarily proposes that the northern South China Sea and the ED of the ECSSB were originally a unified basin and jointly constituted a huge Mesozoic proto‐basin in the East Asian continental margin. The Mesozoic tectonic unit division is helpful not only to discuss and resolve problems of ocean–continent differences and boundaries in southeastern South China but also to understand the tectonic nature of the East Asian continental margin, the dynamic mechanism of the Mesozoic basins and the transition of continental margin types. It also provides scientific support for petroleum exploration of the Mesozoic strata in the East China Sea. Copyright © 2016 John Wiley & Sons, Ltd.