COLLABORATIVE RESEARCH: Paleoventilation of the Southwest Pacific and Southern Ocean in the Holocene and late Quaternary

根据这一奖项，PIS将为冰川和冰川消融的几个时间片建立14C年龄剖面，以便更好地限制西南太平洋和南大洋过去的深水年龄。为此，PIS将对新西兰北部和东部的亚热带和亚南极水域进行沉积物取心探险。邮轮将在新西兰北岛陶波火山带的六个已知含有广泛的火山灰岩层的地点各找回多个岩芯。这些灰烬在陆地上已经确定了很好的年代，提供了地层连接点，并提供了一种方法来确定过去海洋和陆地(大气)碳库的相对年龄。之前关于这些火山灰的岩心的研究表明，最后一次冰川和冰川消融期间的地表和深层水团可能比之前想象的要老几个世纪，而且有争议，因为即使在冰川时期，亚热带地区超过1900年的地表水储存库年龄也被认为是不太可能的。解决这些问题的持续工作一直受到阻碍，因为来自亚热带地区的岩心材料和/或深度覆盖不足，无法继续进行14C的工作，并且火山灰识别存在问题。该项目将收集巨大的活塞芯，以提供足够的沉积物，以从灰烬周围的狭窄沉积物带中获得足够的有孔虫，以适当地识别和测定有孔虫的年代，以便进行与海洋沉积物中火山灰层相关的14C AMS放射性碳测年。

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.