Sediment characteristics around the Okinawa Trough and Kueishantao volcanic island offshore, NE Taiwan

Hsiao-Pei Chang, Andrew, Tien-Shun Lin

Graduate Institute of Geophysics, National Central University

Abstract

This study analysis the gravity cores and piston cores which were taken in 2004-2006 during three cruises onboard R/V Ocean Researcher-I and -II: OR1-800, OR2-1192 and OR2-1325 around Kueishantao Island (water depth between 100 - 500 m ), and Okinawa Trough (900 -1500 m ). We expect to combine the geochronological data, grain size analysis results, X-radiograph images, multiple sensor core logger, mineral composition analysis, and current data to realise the source and transport.

The sediments around Kueishantao Island are silt-dominated. Sedimnets at western part of the island mainly composed of quartz , argillite and slate lithic fragments and the eastern part compose of more pyroxene, hornblende , biotite and other minerals from igneous rocks . Accordingly, we inferred that the sediments at western side were mainly derived from sediments Lan-Yang River , and the sediments at eastern side were mainly derived from NW Taiwan and Kueishantao Island .

In the Southern Okinawa Trough, the sediments are clay -dominated, and mainly composed of quartz, metamorphic lithic fragments (argillite, slate ), and a small amount of igneous lithic fragments . The result suggested that the Kuroshio is the dominant factor that influence the transport of sediments in the SOT, and the Lan-Yang River and eastern Taiwan might be the major source of these sediments.

References

Wei, K.-Y. (2006) Leg 195 synthesis: Site 1202—late Quaternary sedimentation and paleoceanography in the southern Okinawa Trough. In Shinohara, M., Salisbury , M.H., and Richter, C. (Eds.), Proc. ODP, Sci. Results, 195, 1–31.

Huh, C.-A., Su, C.-C., Liang, W.-T., Ling. C.-Y. (2004) Linkages between turbidites in the sourthern Okinawa Trough and submarine earthquakes. Geophysical Research Letters. 31, L12304, doi:10.1029/2004GL019731.

許鶴瀚（ 2007 ）宜蘭陸棚上的淺層沉積構造及沉積物傳輸模式。國立台灣大學海洋研究所碩士論文， 99 頁。