Reconstructing space/time patterns of the Earth's magnetic field in the Holocene from Arctic sedimentary records

对高纬度地区地磁场的认识不足是对地球发电机过程认识的一个基本限制。了解北极的全新世古地磁记录将满足这一需求，并提供一个有价值的所需的约会工具。北极古地磁数据的缺乏是由于北极物流的困难以及古地磁的额外限制。通过与几个专门研究北极湖泊沉积物的小组一起进行全新世古地磁研究，首席研究员通过复制记录表明，北极沉积物可以准确地记录地磁场。古地磁记录与基于纹管的年代学的相互校准允许重建第一个高北极高分辨率古地磁长期变化（PSV）和相对古强度（RPI）记录（2700年）。 这些记录在时间上没有延伸到足够远的地方，无法回答北极地磁场与更深入研究的中纬度地磁场之间千年尺度变化的关系问题。主要研究者将继续这种背负式关系，以解决记录长度、日期曲线的开发问题，并评估PSV和RPI记录的空间模式。2005年野外季节的取芯勘探计划将大大延长（从~ 4.5米延长到~ 20米）沉积物记录。 在加拿大北极群岛、阿拉斯加布鲁克斯山脉和斯瓦尔巴特群岛进行额外的取芯，也有新的机会扩大我们的观测空间。智力优势：最近的地磁观测涵盖了上个世纪，地球发电机理论和建模表明，极地地磁场是独特的，可能与地球的其他地方有很大的不同，但也是全球理解的关键。结果将在时间上扩展，空间上扩展，并完善我们对高北极地磁场的理解。如果极场是唯一的，它应该表现为明显的长期变化行为。 最初的数据表明，它可能在十年到百年的时间尺度上是独一无二的，但可能不是在数百年到千年的时间尺度上，需要更长的记录来测试这一点。所产生的数据将提供唯一的高北极贡献的古球谐模拟计划。北极沉积物的年代测定是困难的，并且仅限于产生纹状沉积物的湖泊。因此。古研究仅限于一小部分可能提供高质量记录的档案。首席研究员已经证明了过去2700年地磁古长期变化与基于纹层的年代学的相互校准，并打算将其扩展到过去8000年，以产生可用于海洋和陆地沉积物的北极主要测年曲线。这项研究将把最近对北磁极剧烈迁移的观察置于历史背景中，以更好地评估目前的地磁行为，包括地磁场强度的显著崩溃，媒体和电视上广泛猜测的即将到来的逆转的可能性。这项工作将提供对历史上极光观测的地理分布的深入了解。研究生培养将是本项目的重点。通过与斯瓦尔巴特REU计划的合作，古环境磁学将成为重点。将通过向国家地球物理数据中心和目前完全缺乏北极高纬度古地磁数据的其他数据库和建模倡议提供古地磁数据集。

ABSTRACTStonerOPP-0520533A lack of understanding of the geomagnetic field at high latitudes has been a fundamentallimitation to understanding of the geodynamo process. An understanding of the Arctic's Holocene paleomagnetic record would fill this need and provide a valuable needed dating tools. The lack of Arctic paleomagnetic data results from the difficulty of Arctic logistics and with the added constraints of paleomagnetism. Through piggybacking Holocene paleomagnetic studies with several groups who specialize in the study of high Arctic lake sediments, the Principal Investigator shows through replicate records that Arctic sediments can accurately record the geomagnetic field. The inter-calibration of the paleomagnetic record with varve-based chronologies allows reconstruction of the first high Arctic high-resolution paleomagnetic secular variation (PSV) and relative paleointensity (RPI) records (2700 yrs.). These records do not extend far enough back in time to answer questions on the relationship of the millennial scale variability between the geomagnetic field of the Arctic to that of the more thoroughly studied mid-latitudes. The Principal Investigator will continue this piggyback relationship to address issues of record length, development of dating curves and to assess spatial patterns of the PSV and RPI records. Coring expeditions schedule for the 2005 field season will significantly lengthen (from ~ 4.5 to ~ 20 m) sediment records. New opportunities are also available to spatial expand our observations with additional coring in the Canadian Arctic Archipelago, Alaskan Brooks Range and Svalbard. Intellectual Merit: Recent geomagnetic observations covering the last century, geodynamo theory, and modeling suggest that the polar geomagnetic field is unique and possibly substantially different from the rest of the Earth, but also a critical to piece to a global understanding. Results will temporally extend, spatially expand, and refine our understanding of the geomagnetic field of the High Arctic. If the polar field is unique, it should manifest as distinct secular variation behavior. Initial data suggest that it may be unique on decadal to centennial timescales, but possibly not at multi-centennial to millennial timescales and longer records are needed to test this. The data generated will provide the only high Arctic contribution to paleo spherical harmonic modeling initiatives. Dating of Arctic sediments is difficult, and limited to lakes producing varved sediments. Thus. paleo-studies are limited to a small subset of the potential archives that could provide high quality records. The Principal Investigator has demonstrated the inter-calibration of geomagnetic paleosecular variation with varve-based chronologies for the last 2700 yrs. and intends to extend this to the last 8000 yrs to produce a primary dating curve for the Arctic that can be used for both marine and terrestrial sediments.Broader Impacts: This research will place recent observations of dramatic migration ofthe North Magnetic Pole into a historical context to better assess the present geomagnetic behavior including the prominent collapse of geomagnetic field intensity and the possibility of an upcoming reversal that has been widely speculated on in press and television. This work will provide insights into the geographical distribution of historical aurora observations. Graduate student training will be a focus of this project. Through collaborations with the Svalbard REU Program, paleo-and-environmental magnetism will be a focus. Paleomagnetic datasets will be made available through contribution to the national geophysical data center and to other database and modeling initiatives that at present are completely devoid of high Arctic paleomagnetic data.