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

摘要：北冰洋的古海洋学和古气候历史，特别是最近几十万年的历史，在很大程度上仍然是未知的，因为在30 ~ 800 ka （kyr）时间范围内的沉积物岩心的数值定年存在困难。目标是对年龄小于100 ka的关键矿床进行数值定年，这对当地和整个海洋的年代地层学的发展至关重要。在北冰洋的勘测工作表明，光子激发发光（PSL）和热释光（TL）测年对某些海岭的前全新世间冰期沉积物有很好的应用前景。Jakobsson等人的研究表明，在海洋中央脊顶位置的最后间冰期层位的PSL定年可以精确地定年。然而，由于首席研究员只分析了几个岩心顶部，因此对大量局部颗粒输运过程的PSL定年精度的可能影响仍未量化，并且PSL在这一重要的冰期-间冰期时间范围内的潜在效用尚不确定。他将把PSL方法应用于2005年希利-奥登跨北极考察（HOTRAX05）期间收集的其他岩芯顶部和下岩芯层。知识价值：项目结果将量化北冰洋沉积物现代发光测年方法的潜力。通过牢固地建立该地区的PSL测年，该项目将扩大北冰洋第四纪古海洋学和古气候知识及其与亚极地全球系统的联系。实验室的努力将能够验证首席研究员的假设，即楚科奇边境地区至少有利于对全新世之前的地平线进行光子测年。该项目将确定阿尔法脊对未来发光沉积物测年的适用性，并将测试先前首席研究员在罗蒙诺索夫脊的结果，即只有80至90 kyr的地平线适合PSL测年。此外，该项目可能会解决首席研究员记录的关于门捷列夫岭复合沉积物PSL定年适用性的模糊问题。独特的是，该项目还将量化脏海冰（在融化时）对底部沉积物中非零PSL信号的贡献程度。最后，该项目将测试单粒石英PSL定年的能力，以分离年龄小于100 ka的岩心层位中含有冰漂砂的真实埋藏年龄，并将使用这些单粒分析的结果来测试楚科奇边境地区冰磨历史时间的最新假设。更广泛的影响：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募学生。它将通过参与DRI建立的教师培训计划，为内华达州的K12系统贡献知识和经验。研究成果将通过同行评议期刊的出版物和在项目最后一年的会议发言中传播。通过发展对北冰洋沉积物进行精确数值定年的能力，拟议的研究将导致对第四纪冰期-间冰期时间尺度上北半球气候演变的基本理解。

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.