Under this award the PIs will construct a profile of 14C ages for several time slices in the glaciation and deglaciation in order to better constrain past deep water age of the southwest Pacific and Southern Oceans. To do this, the PIs will perform a sediment coring expedition to the subtropical and subantarctic waters to the north and east New Zealand. The cruise will recover multiple cores at each of six locations that are known to contain widespread tephra layers from the from the Taupo volcanic zone on the North Island of New Zealand. These ashes have been well dated on land and provide stratigraphic tie points and a means to establish the relative ages of marine and terrestrial (atmospheric) carbon reservoirs in the past. Previous work on preexisting cores with these ashes has demonstrated that surface and deep water masses in the last glaciation and deglaciation could be centuries older than previously imagined and controversial because surface water reservoir ages in subtropical locations of more than 1900 yrs are considered unlikely even in the glaciation. Continued work to resolve these issues has been hampered because cores from subtropical locations have either insufficient material and/or depth coverage for continued work on 14C and have problematic ash identification. This project will collect giant piston cores to provide sufficient sediment to obtain enough foraminifera from a narrow sediment band surrounding the ashes to properly identify and date the tephras in order to conduct 14C AMS radiocarbon dating foraminifera associated with ash layers in the marine sediment.
