Japan Geoscience Union Meeting 2016

Presentation information

International Session (Oral)

Symbol S (Solid Earth Sciences) » S-IT Science of the Earth's Interior & Techtonophysics

[S-IT11] Geodynamic evolution of northeast Asia and western Pacific

Tue. May 24, 2016 3:30 PM - 5:00 PM A05 (APA HOTEL&RESORT TOKYO BAY MAKUHARI)

Convener:*Gaku Kimura(Department of Earth and Planetary Science of the Graduate School of Science, The University of Tokyo), Jonny Wu(Department of Geosciences, National Taiwan University), Timothy Byrne(University of Connecticut), Kyoko Okino(Ocean Research Institute, University of Tokyo), Chair:Timothy Byrne(University of Connecticut), Jonny Wu(Department of Geosciences, National Taiwan University)

3:30 PM - 3:45 PM

[SIT11-07] Greater South China: it was larger than previously believed

*Yukio Isozaki1, Hiroki Nakahata1, Shuhei Sakata1, Takafumi Hirata2 (1.Department of Earth Science and Astronomy, Multi-disciplinary Sciences - General Systems Studies, Graduate School of Arts and Sciences, The University of Tokyo, 2.Department of Geology and Mineralogy, Kyoto University)

Keywords:South China, Japan, Primorye, CAOB

Long-remaining unsolved issues include the Neoproterozoic to Paleozoic geotectonics of proto-Japan, in particular, precise timing of the onset of the Pacific sudbduction (or tectonic turnover from a passive to an active margin) and the homeland o f Japan (North China or South China). To date, the nascent development of an arc-trench system of proto-Japan is reasonably constrained in timing to the early Cambrian or slightly older age. The other new view recently given by zircon chronology was the identification of older Precambrian detrital zircons and xenocrysts, in particular, the Neoproterozoic grains with similar ages to those of the South China basement. The North China block has been tradi tionally regarded as the homeland continent, along which Japan evolved. Detrital zircons of so-called Pan-African ages (ca. 1200-600 Ma) are identified, however, in various Paleozoic sandstones (Nakama et al., 2010; Isozaki et al., 20 14); in addition, zircon xenocrysts of the similar ages were also recognized in the Paleozoic granitoids (Aoki et al., 2015) . These ages are extremely rare in the North China block, whereas dominant in South China. The latest identification of the extensive Paleo- to Mesoproterozoic crusts in the Cathaysian part of South China cleared the difficulty in correlating Japan with South China. These data confirmed that Paleozoic Japan corresponded to an eastern extension of South China block prior to the Triassic collision with North China. This requires that the original South China block was much larger than the present conterminous mainland part, i.e., longer for more than 200 km to the northeast up to NE Japan, and the Greater South China (GSC) was proposed particularly for proper paleogeographic reconstruction of East Asia (Isozaki, 2014). The lastest information on the detrital zircon age spectra from the Paelozoic sandstones of the Sergeevka belt in Primorye (Far East Russia) further suggests that this domain resembles Japan, and South China in terms of sedimentary settings and provenance . In short, the GSC becomes much larger, nealry twice larger, than previsouly imagined.