Coeval Evolution of the Eastern Philippine Sea Plate and the South China Sea in the Early Miocene: Paleomagnetic and Provenance Constraints From ODP Site 1177

The Philippine Sea Plate (PSP) and the South China Sea (SCS), located at the intersection of the Eurasian, Pacific, and Indo‐Australian plates, are key areas for global plate reconstruction. However, the relationships between the PSP and the SCS are still elusive. Here we report a new paleolatitude determination (16.0° ± 4.5°N at ∼20 Ma) from the Ocean Drilling Program Site 1177 in the Shikoku Basin (SB) within the eastern PSP. The new results indicate that the SB had a geographical affinity with the SCS in the early Miocene. Furthermore, the similarity in the U‐Pb zircon age spectra of early Miocene turbidites from SB Site 1177 and SCS Site X28 implies that the two sites might receive similar materials in the early Miocene. Based on the new paleolatitude, provenance results, and other constraints, we suggest that the eastern PSP might be coupled dynamically to the SCS in the early Miocene. Plain Language Summary Tectonic evolution models of the Philippines Sea Plate (PSP) and the South China Sea (SCS) have been independently developed. However, the geographical and dynamic relationships between the PSP and the SCS remain unclear due to the limited paleomagnetic data from the Shikoku Basin (SB) and the uncertainty of the its provenance in the early Miocene. In this study, paleomagnetic results from the Ocean Drilling Program Site 1177 indicate that the SB had a similar paleolatitude with the SCS at ∼20 Ma, and the zircon U‐Pb chronological results further suggest that the SB and the SCS received similar materials from the Pearl River in the early Miocene. These new lines of evidence, in combination with other existing observations, strongly indicate that the SB might be coupled dynamically to the SCS in the early Miocene. Key Points A new paleolatitude (16.0° ± 4.5°N at ∼20 Ma) was obtained from the Shikoku Basin The Shikoku Basin and the South China Sea had similar provenances from the Pearl River in the early Miocene The Shikoku Basin might be coupled dynamically to the South China Sea in the early Miocene