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

BergerOPP-0612950概述：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，仍然很大程度上是未知的，因为在30到800ka(KYR)的时间范围内，沉积岩心的数字测年存在困难。目标是对小于100ka的关键矿床进行数字测年，这对当地和整个海洋年代地层学的发展至关重要。北冰洋的调查工作表明，光致发光(PSL)和热释光(TL)测年在某些海脊的前全新世间冰期沉积中具有良好的应用前景。Jakobson et.等人的PSL测年结果表明，中央洋脊顶部末次间冰期的PSL测年方法可以准确地确定其年龄。然而，由于首席调查员只分析了几个岩心顶部，许多当地谷物运输过程对PSL测年精度的可能影响仍然没有量化，PSL在这一重要的冰川-间冰期时间范围内的潜在用途尚不确定。他将把PSL方法应用于2005年Healy-Oden跨北极探险(HOTRAX05)期间收集的额外岩心顶部和下面的岩心层位。智力优势：项目结果将量化北冰洋沉积物现代发光测年方法的潜力。通过坚定地确定该区域的PSL测年，该项目将扩大北冰洋的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。实验室的工作将使首席研究员的假设得以验证，即楚科奇边界地区有利于至少在全新世之前的地层层的光子测年。该项目将确定阿尔法山脊对未来发光沉积物测年的适宜性，并将测试Lomonosov山脊先前主要调查者结果的含义，即只有80至90KYR层位适合进行PSL测年。此外，该项目可能会解决首席调查员记录的关于门捷列夫海脊杂岩沉积物PSL测年的适宜性的模糊问题。独特的是，该项目还将量化肮脏的海冰(在融化时)对海底沉积物中非零PSL信号的贡献程度。最后，该项目将测试单颗粒石英PSL测年在小于100 ka的岩心层位中分离真实埋藏年龄的能力，并将使用这些单颗粒分析的结果来测试最近关于楚科奇边界冰山历史时间的假设。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收学生。它将通过参与DRI既定的教师培训计划，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上的出版物和最后项目年的会议陈述来传播。通过开发对北冰洋沉积物进行准确的数字测年的能力，拟议的研究将有助于从根本上了解北半球气候在第四纪冰川-间冰期间隔时间尺度上的演变。

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.