Constructing a Dating Tool for the last 100 kyr of Arctic Ocean Sediments: Extended Photonic Dating Tests and Applications using HOTRAX05 Cores

摘要：由于难以对30 ~ 800 ka（kyr）时间范围内的沉积物岩心进行数字定年，北冰洋的古海洋学和古气候历史，特别是过去几十万年的历史，在很大程度上仍然是未知的。目标是对年龄小于100 ka的关键矿床进行数字定年，这对发展当地和海洋年代地层学至关重要。在北冰洋的考察工作表明，光释光（PSL）和热释光（TL）定年法在某些海脊的前全新世间冰期沉积物中是有希望的。雅各布森等例如，结果表明，PSL测年法可以准确测定大洋中脊顶末次间冰期层位的年龄。然而，由于主要研究人员只分析了几个核心顶部，可能对PSL测年的准确性的主机当地的谷物运输过程的影响仍然无法量化，PSL在这一重要的冰川间冰期的时间范围内的潜在效用是不确定的。他将把PSL方法应用于2005年Healy-Oden跨北极考察（HOTRAX 05）期间收集的其他岩心顶部和岩心下层。 知识价值：项目结果将量化现代发光测年方法对北冰洋沉积物的潜力。 通过为该地区建立PSL测年，该项目将扩大对北冰洋及其与亚极地全球系统的联系的第四纪古海洋学和古气候学知识。实验室的努力将使测试首席研究员的假设，楚科奇边境地区是有利的光子测年至少前全新世地平线。该项目将确定阿尔法海岭未来发光沉积物测年的适用性，并将测试罗蒙诺索夫海岭先前主要研究人员结果的含义，即只有80至90 kyr的地层适合PSL测年。此外，该项目可能会解决一个主要研究者记录的模糊性的适合PSL测年的沉积物沿着门捷列夫岭复杂。独特的是，该项目还将量化脏海冰（融化后）对底部沉积物中非零PSL信号的贡献程度。最后，该项目将测试单颗粒石英PSL测年法在分离约100 ka以下和含有冰筏砂的岩芯层位的真实埋藏年龄方面的能力，并将利用这些单颗粒分析的结果来测试最近关于楚科奇边疆冰搁浅历史时间的假设。这项研究将支持研究生和本科生，重点是从代表性不足的群体中招收学生。它将通过参加DRI的既定教师培训计划，为内华达州的K12系统提供知识和经验。 研究结果将通过在同行评审期刊上发表的文章和在最后一个项目年度的会议上发表的演讲来传播。通过发展对北冰洋沉积物进行精确数字测年的能力，拟议的研究将导致对北方半球气候在第四纪冰期-间冰期时间尺度上的演变有基本的了解。

ABSTRACTBergerOPP-0612950Overview: The paleoceanographic and paleoclimatic history of the Arctic Ocean, especially during the last several hundred thousand years, remains largely unknown because of difficulties in numerical dating of sediment cores in the 30 to 800 ka (kyr) time range. The goal is numeric dating of key deposits younger than about 100 ka, which is critical for development of local and oceanwide chronostratigraphies. Reconnaissance work in the Arctic Ocean shows that photonstimulated- luminescence (PSL) and thermoluminescence (TL) dating are promising for pre-Holocene interglaciation deposits at some ridge. Jakobsson et. al., showed that PSL dating of last-interglaciation horizons at a central-ocean ridge-top site can be accurately dated by PSL. However, because the Principal Investigator analyzed only a few core tops, likely effects on PSL dating accuracy of a host of local grain-transport processes remain unquantified, and the potential utility of PSL in this important glacial-interglacial time range is uncertain. He will apply PSL methods to additional core tops and down-core horizons collected during the 2005 Healy-Oden Trans-Arctic Expedition (HOTRAX05). Intellectual merit: Project results will quantify the potential of modern luminescence dating methods for Arctic Ocean sediments. By firmly establishing PSL dating for this region, the project will permit expansion of Quaternary paleoceanographic and paleoclimatic knowledge of the Arctic Ocean and its links to subpolar global systems. The laboratory effort will enable testing the Principal Investigator's hypothesis that the Chukchi Borderland region is favorable for photonic dating of at least pre-Holocene horizons. The project will determine the suitability of the Alpha Ridge for future luminescence sediment dating and will test an implication of prior Principal Investigator results at the Lomonosov Ridge that only horizons 80 to 90 kyr there are suitable for PSL dating. Also, this project may resolve a Principal Investigator documented ambiguity about the suitability for PSL dating of sediments along the Mendeleev Ridge complex. Uniquely, this project also will quantify the extent to which dirty sea ice contributes (upon melting) to non-zero PSL signals in the bottom sediments. Finally, this project will test the capability of single-grain-quartz PSL dating for isolating true burial ages in core horizons younger than about 100 ka and containing ice-rafted sand, and will use the results of these single-grain analyses to test recent hypotheses of the timing of ice-grounding histories in the Chukchi Borderland.Broader impacts: This study will support graduate and undergraduate students, with emphasis on recruiting students from underrepresented groups. It will contribute knowledge and experience to Nevada's K12 system through participation in an established teacher training program at DRI. Research results will be disseminated through publications in peer-reviewed journals and at final-project-year conference presentations. Through development of a capability for accurate numeric dating of the Arctic Ocean sediments, the proposed research will lead to fundamental understanding of the evolution of the Northern Hemisphere climate on timescales of Quaternary glacial-interglacial intervals.