IODP EXPEDITION 346 SITE U1427: CALCAREOUS NANNOFOSSIL CHANGES DURING THE MID-PLEISTOCENE TRANSITION (MPT)

IODP Expedition 346 drilled a latitudinal transect in the Japan Sea/East Sea, as well as two sites in the northern East China Sea in order to investigate Asian monsoon variability and orbital- and millennial-scale changes in circulation and surface productivity in the Japan Sea/East Sea during at least the last 5 million years. Over 6.1 km of core were recovered, including approximately 550 meters of Pleistocene sediments dominated by nannofossil-rich or biosiliceous-rich clayey silt at Site U1427 (the southernmost and shallowest site encountered during Expedition 346). Sedimentation rates established at U1427 show little variation and average approximately 36 cm/ky. The lack of coring gaps at this site coupled with high sedimentation rates make it ideal for high resolution nannofossil biostratigraphy across the Mid-Pleistocene Transition (MPT). The MPT is characterized by a glacial-interglacial cycle periodicity switch from 41 to 100 ky cycles and is associated with changes in climate, including lower global temperatures, increased ice volume, and lower sea surface temperatures. Preliminary shipboard data suggest that downhole changes in benthic foraminifera assemblages reflect changing paleoenvironmental conditions, potentially related to distinct phases of Pleistocene climate evolution. My primary research objective is to evaluate changes in nannofossil assemblage composition across the MPT, including Marine Isotope Stages 16 through 36, at Site U1427. Preliminary data are presented which were collected during and analyzed following completion of Expedition 346 in October, 2013. This abstract is co-authored by the IODP Expedition 346 Science Party.