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

Abstract

Over the past several decades, evolution models for both the PSP and the SCS have been established reasonably. For example, the time of the NNW oriented seafloor spreading of the SCS along the South China Block was calibrated to begin at 33 Ma and cease at 15 Ma, respectively, during which the east subbasin (33-15 Ma) formed first and the southwest subbasin (23.6-16 Ma) formed later (

The Early Miocene Provenance Shift of ODP Site 1177 and Implications for the Tectonic Evolution of the Shikoku Basin, Philippine Sea Plate

“…Unit IV represents volcaniclastic-rich facies and Unit V is the basalt basement. In Units III and IV, the zircon age spectrum of turbidites was determined (Clift et al, 2013;Liu et al, 2021) (Figure 2C). The results indicated that the Pearl River zircons were found in the silt turbidites at ~18.6 Ma and the Yangtze River zircons were found in the sand turbidites at ~15.4 Ma.…”

“…Given that the Izu-Bonin Arc is mainly composed of basalt, which contributes greatly to the formation of smectite (Fagel et al, 2001), Underwood and Fergusson (2005) speculated that the early Miocene provenance might derive from the Izu-Bonin Arc. Recently, Liu et al (2021) suggested that the silt turbidites from Site 1177 were sourced from the Pearl River on the basis of similar zircon age spectra between Site 1177 and Site X28 (Figure 2C).…”

“…The Philippine Sea Plate is uniquely located among the Eurasian, Pacific, and Indo-Australian plates, and is of great importance to fundamental plate tectonic theory and global tectonic evolution (Hall, 2002;Reagan et al, 2010;Wu et al, 2016;Maunder et al, 2020;Sibuet et al, 2021). The Philippine Sea Plate is not only a natural laboratory for the study of plate tectonics on aspects of initial subduction, arc rifting, and back-arc spreading (Reagan et al, 2010;Arculus et al, 2015;Maunder et al, 2020;Chen et al, 2021;Li et al, 2021) but is also significant for the tectonic reconstruction of the West Pacific and East Asia (Hall, 2002;Zahirovic et al, 2014;Lallemand, 2016;Wu et al, 2016;Ma et al, 2019;Queaño et al, 2020;Liu et al, 2021;Sibuet et al, 2021).…”

“…Thus, the study of Site 1177 provenance can shed light on the Miocene tectonic evolution of the Shikoku Basin, even the Philippine Sea Plate. Previous studies have constructed the tectonic evolutionary models of the Philippine Sea Plate based on evidences from paleomagnetism (Louden, 1977;Kinoshita, 1980;Keating, 1981;Keating and Herrero, 1981;Bleil, 1982;Haston and Fuller, 1991;Haston et al, 1992;Koyama et al, 1992;Hall et al, 1995;Queano et al, 2007;Yamazaki et al, 2010Yamazaki et al, , 2021Richter and Ali, 2015;Liu et al, 2021), submarine magnetic anomaly (Okino et al, 1999;Sdrolias et al, 2004), seismic tomography (Zahirovic et al, 2014;Wu et al, 2016;Ma et al, 2019;Sibuet et al, 2021) and sedimentary provenance (Clift et al, 2013;Saitoh et al, 2015), etc. Researchers agreed on the first-order evolution that the Philippine Sea Plate moved ~20 °northward from the equator to the present position and simultaneously rotated ~90 °clockwise since the Eocene (Hall, 2002;Yamazaki et al, 2010;Zahirovic et al, 2014;Wu et al, 2016;Ma et al, 2019;Liu et al, 2021).…”

“…On the one hand, the research materials are different. Mudstones (Underwood and Fergusson, 2005) and turbidites (Liu et al, 2021) in the sedimentary sequence experienced different sedimentary processes and, therefore, may have originated from different sources. On the other hand, the above-mentioned studies are generally based on a certain method but lack comprehensive analysis.…”