Scheduled Cruises in 2002

Summary of a recent cruise on margins research (JP.021)

Location :   Mariana Arc

Research ship and cruise identifier :   Kairei

Sails :   28 October 2002 from Guam

Docks :   12 November 2002 in Yokosuka

Principal Scientist/Investigator :   N. Seama

Laboratory :   Kobe University, Japan

Other investigators :   T. Goto, M. Ichiki,

E-mail contact for further information :   seama@kobe-u.ac.jp

Scientific objectives :    (1) We have conducted a preliminary seafloor MT experiment using OBEM (Ocean Bottom Electro-Magnetometer) as a first step towards imaging the deep conductivity structure across the central Mariana subduction system from the subducting Pacific plate, fore-arc, island arc, the Mariana Trough backarc basin, to the Parece-Vela Basin. We deployed 10 OBEMs using the R/V Yokosuka cruise in October 2001, recovered two of them during an R/V Ewing cruise in April, and will recover the rest of them during this R/V Kairei cruise. This study has two purposes; i) to understand the melt structure feeding the slow spreading axis of the Mariana Trough and ii) to image the overall mantle conductivity structure across the Mariana subduction system.

(2) We will test the MOSES (Magnetometric Off-Shore Electrical Sounding) system at a hydrothermal site in the Suiyo Seamount, the Izu-Bonin Island Arc, Western Pacific. The system has been newly developed to derive the electrical conductivity structure of a shallow part of the oceanic crust. The results from the hydrothermal site would allow us to understand overall features of the hydrothermal system.