M.J. Vautravers , Expedition 350 Scientists
06 July 2016
International Ocean Discovery Program (IODP) Expedition 350 cored Site U1436 at intermediate water depth (1776 meters below sea level) in the western part of the Izu fore-arc basin, ~60 km east of the arc-front volcano, Aogashima. Site U1436 lies 1.5 km west of Ocean Drilling Program Site 792 (Leg 126). Site U1436 (proposed Site IBM-4), conceived as a 150 m deep geotechnical test hole for future deep drilling (5500 meters below seafloor) with the D/V Chikyu, provides a rich record of Pleistocene volcanism. Isotopic stratigraphy data reported here extend the timescale and improve the precision of the shipboard-determined biostratigraphy to enhance further investigations on the nature, origin, and rhythm of the volcanic eruptions recorded at this site. The δ18O and δ13C values in selected samples containing planktonic foraminifers (Neogloboquadrina dutertrei) were measured over the 70 m long record from Hole U1436C. Isotopic ratios were determined for 167 samples and are examined in conjunction with nannofossil and planktonic foraminifer datums obtained during Expedition 350. These data allow fairly good identification of all marine isotope stages over the last 1 My. The results from this data report provide a refined age scale that will enhance the scientific appeal of this site to volcanologists and sedimentologists and increase the potential impact of their interpretations in later research stages. Hole U1436C was cored near the Kuroshio Current in the North Pacific Ocean realm, where any new paleoceanographic and paleoclimatologic data would be valuable. Furthermore, the refined stratigraphic framework from this study also clearly shows that the original goals of Expedition 350 can easily be expanded beyond that of the study of the evolution of the Earth’s crust toward new targets focused on Earth surface processes.