Y. Tamura , C.J. Busby , P. Blum , G. Guèrin , G.D.M. Andrews , A.K. Barker , J.L.R. Berger , E.M. Bongiolo , M. Bordiga , S.M. DeBari , J.B. Gill , C. Hamelin , J. Jia , E.H. John , A.-S. Jonas , M. Jutzeler , M.A.C. Kars , Z.A. Kita , K. Konrad , S.H. Mahony , M. Martini , T. Miyazaki , R.J. Musgrave , D.B. Nascimento , A.R.L. Nichols , J.M. Ribeiro , T. Sato , J.C. Schindlbeck , A.K. Schmitt , S.M. Straub , M.J. Vautravers , Y. and Yang
30 May 2015
International Ocean Discovery Program (IODP) Site U1436 was drilled as a geotechnical survey requirement for proposed D/V Chikyu drilling at Site IBM-4. Site U1436 is located at 32°23.88′N, 140°21.93′E in the Izu arc. It lies 1776 m below sea level in the western half of the Izu fore-arc basin, about 60 km east of the arc-front volcano Aogashima and 170 km west of the axis of the Izu-Bonin Trench. Because Site U1436 is a geotechnical hole for proposed Site IBM-4, the first part of this section focuses on the background and objectives for Site IBM-4 ultradeep (~5.5 km) drilling to arc middle crust, which is inferred to represent juvenile continental crust. However, Site U1436 yielded a rich record of Quaternary explosive volcanism; therefore, the second half of this section provides background on Quaternary volcanism in the Izu-Bonin arc and objectives for ash recovered. IODP Expedition 350 drilled only 150 m at Site U1436 because this was sufficient to meet the geotechnical survey requirements for Chikyu drilling. We successfully obtained 10 geotechnical core samples from 2.5 to 104 meters below seafloor (mbsf), which have been kept in the refrigerator for postcruise transfer to the Kochi Core Center.