Reconstructing the framework of the Paleo-Pacific Plate: A synthetic review

Abstract

The Paleo-Pacific Ocean Basin would evolve from the Panthalassa and develop ancient plates such as Paleo-Pacific, Farallon and Phoenix. Multilines of geological and geophysical evidence indicate that a new-born plate, named the Pacific Plate, would initially develop at 190 Ma among these three plates in the Paleo-Pacific Ocean Basin, but it did not take shape until 55 Ma when the Paleo-Pacific Plate would finally disappear on the East Asian continental margin. Therefore, the Paleo-Pacific Plate and the Pacific Plate would co-evolve or co-exist from 190 Ma to 55 Ma in the Paleo-Pacific Ocean Basin. The ocean basin after the complete disappearance of the Paleo-Pacific Plate at 55 Ma is the Pacific Ocean Basin as presently seen. Geologically, the Pacific Ocean Basin is marked by the initial formation of the plate configuration on the current Pacific seafloor in the Mesozoic. Therefore, when did the Paleo-Pacific Plate begin in the Paleo-Pacific Ocean Basin? When was the Paleo-Pacific Plate subducted beneath the East Asian continental margin? How would its appearance and disappearance are spatiotemporally recorded in geology? What are its geological effects during its subduction beneath the East Asian continental margin? Although there are numerous studies dealing with the formation and evolution of the Paleo-Pacific Plate, the results have brought many big debates on its composition and structure. Some scholars refer to the Paleo-Pacific Plate differently, leading to some great difficulties in academic exchanges. There are three mainstream viewpoints: the Paleo-Pacific Plate is either the Kula Plate, or the Izanagi Plate, or a collage of many plates. Although the Paleo-Pacific Plate existed as a mysterious on Earth in the Mesozoic, a large number of geological observations indicate that its evolution is closely related to the tectonic evolution of the East Asian continental margin in this period. Therefore, it is necessary to recognize and reconstruct the configuration of the Paleo-Pacific Plate and its tectonic effects on the East Asian continental margin. This paper attempts to systematically summarize the previous observations and interpretations of the Paleo-Pacific Plate, to distinguish between the concepts of the Kula Plate, the Izanagi Plate and the Paleo-Pacific Plate in different study stages, and to systematically explore various differences in plate reconstruction since the proposal of the Paleo-Pacific Plate. Based on the current progresses on plate tectonics, this paper also summarizes the relevant geological records of the Paleo-Pacific Plate, including the continental margin accretion of oceanic plateaus, island arc basalt-like magmatic rocks and terrane-collage accretion. The time of its subduction initiation, geometric evolution and spatial range changes are explored, and its tectonic evolutionary history is reconstructed. Finally, remaining problems are presented for the future research.