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

根据该合同，PIs将在冰川和冰川消退的几个时间片段中构建14C年龄的剖面图，以便更好地约束西南太平洋和南大洋过去的深水时代。为此，pi将在新西兰北部和东部的亚热带和亚南极水域进行沉积物取样考察。邮轮将在六个地点中的每个地点回收多个岩心，这些地点已知含有来自新西兰北岛陶波火山带的广泛的火山层。这些灰烬已经在陆地上确定了很好的年代，并提供了地层结合点和一种方法来确定过去海洋和陆地（大气）碳库的相对年龄。先前对这些灰烬预先存在的岩心的研究表明，末次冰期和去冰期的地表和深水团可能比先前想象的要早几个世纪，这是有争议的，因为即使在冰期，亚热带地区的地表水水库的年龄也不太可能超过1900年。继续解决这些问题的工作受到了阻碍，因为亚热带地区的岩心要么没有足够的材料和/或深度覆盖，无法继续进行14C的研究，而且灰烬识别也存在问题。该项目将收集巨大的活塞岩心，以提供足够的沉积物，从灰烬周围狭窄的沉积物带中获得足够的有孔虫，以正确识别和确定tephras的年代，从而对海洋沉积物中与灰烬层相关的有孔虫进行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.