Magnetostratigraphy and Rock Magnetism of Expedition 318 Sediments

知识价值IODP远征318的总体目标，1月？2010年3月（惠灵顿？霍巴特）是：1）确定冰到达威尔克斯地边缘的时间，2）确定从湿基到冷基冰川状态的可能过渡的性质和年龄，3）获得新第三纪晚期和第四纪期间南极气候变化的高分辨率记录，以及4）从Ad 'elie盆地的钻探中获得全新世的超高分辨率记录。IODP第318号考察队钻探了7个地点，并恢复了2500米的下始新世至全新世沉积物。318号探险队的一个关键目标是记录沉积物和沉积间断的年龄。初步的磁性地层数据提供了至关重要的限制，以及校准的生物地层在南大洋，直接校准是非常罕见的。例如，在大洋钻探第189航次期间从塔斯马尼亚共轭边缘钻探的岩心恢复了类似年龄的沉积物，但到目前为止，古近系部分的磁性地层学不足以校准地质时间尺度。来自远征318号沉积物的磁性组构、矿物学和粒度信息为这一独特沉积序列中记录的环境变化提供了有趣的线索。IODP第318次考察的另一个主要目标是从Ad 'elie盆地的钻探中获得全新世的超高分辨率记录，Ad' elie盆地是一个190米厚的淤泥质软泥序列，覆盖在年龄为#8764;11 ka的冰川杂岩上。站点U1357揭示了来自南大洋的海洋和气候变化的第一个年度解析时间序列。U1357 A的存档一半的船上测量获得的数据记录了地磁场长期变化（SV）的无与伦比的记录，这不仅保证了前所未有的SV记录，而且将提供关键的约束孔到孔的相关性。该提案要求提供资金，对318号考察队钻探获得的材料进行古地磁和岩石磁力分析。它还寻求适度的资金，用于ODP第189航次期间钻探的岩心的取样和分析，这些岩心存放在日本高知储存库。更广泛的影响--新生代冰川的历史，揭示了氧同位素值的汇编及其与推断的大气CO2的关系，具有重大的科学意义。南极冰冻圈在全球气候系统中发挥着关键作用，因此其历史在当前的气候变化辩论中发挥着作用。建议的工作是必不可少的放置威尔克斯土地沉积到一个高分辨率的年代地层框架。全球古长期变化模型对于探索地磁场的行为，作为古地磁学的定年工具以及评估地磁场对放射性碳生产的控制的手段是非常有用的。尽管有广泛的实用性，但这些模型只与它们所来源的数据一样好，到目前为止，南半球的记录很少。此外，迄今为止获得的任何记录都没有在站点U1357处可实现的分辨率。因此，建议的工作有可能大大改善古长期变化模型。这一建议也将有助于博士后学者Saiko Sugisaki博士的教育。她在318远征队中担任船上的古地磁学家，尽管她的训练是光学刺激发光。她花了几个月的时间深入地从事古地磁研究，并参加了斯克里普斯提供的在线古地磁课程（http：//magician.ucsd.edu/#8764;ltauxe/sio247），她决定在斯克里普斯的古地磁实验室继续她的博士后学习。PI是众所周知的推广工作，以更广泛的社区，通过举办短期课程，通过使教科书的古地磁学的基本要素可供免费访问，通过举办在线，免费访问，课程，并通过使PmagPy古地磁软件包开源。本提案将为这些教育/外联活动提供部分支助

Intellectual MeritThe overall objectives of IODP Expedition 318, January ? March 2010 (Wellington ? Hobart) were: 1) to determine the timing of the arrival of ice at the Wilkes Land margin, 2) to determine the nature and age of possible transitions from a wet-based to a cold based glacial regime, 3) to obtain a high-resolution record of Antarctic climate variability during the late Neogene and Quaternary, and 4) to obtain an ultra high resolution record of the Holocene from drilling in the Ad´elie Basin. IODP Expedition 318 drilled seven sites and recovered ∼2500 m of Lower Eocene to Holocene sediments. A critical aspect of the stated goals of Expedition 318 is documenting the age of the sediments and sedimentary hiatuses. Preliminary magnetostratigraphic data provide crucial constraints as well as calibration for the biostratigraphies in the Southern Ocean, where direct calibration is notably scarce. For example, cores from the conjugate margin of Tasmania drilled during ODP Leg 189 recovered sediments of similar age, but the magnetic stratigraphy for the Paleogene portion so far is inadequate for the purposes of calibrating the geological time scale. Magnetic fabrics, mineralogy and grain size information from Expedition 318 sediments provide intriguing clues to environmental changes recorded in this unique sedimentary sequence. Another prime objectives of IODP Expedition 318 was to obtain an ultra high resolution record of the Holocene from drilling in the Ad´elie Basin, a 190 m thick sequence of diatomaceous ooze overlying a glacial diamict with an age of ∼11 ka. Site U1357 revealsh the first annually resolved time series of oceanographic and climatic variability derived from the Southern ocean. Data obtained from shipboard measurements of the archive half of U1357A documented an unrivaled record of secular variation (SV) of the geomagnetic field, which promises not only an unprecedented SV record but also will provide critical constraints for hole to hole correlation. This proposal requests funds for the paleomagnetic and rock magnetic analyses of material obtained from Expedition 318 drilling. It also seeks modest funding for sampling and analysis of cores drilled during ODP Leg 189 and housed in the Kochi Repository in Japan.Broader ImpactsThe history of Cenozoic glaciation as revealed by compilations of oxygen isotopic values and its relationship to inferred atmospheric CO2 is of major scientific interest. The Antarctic cryosphere plays a key role in the global climate system and its history therefore plays a role in the current climate change debate. The proposed work is essential for placing the Wilkes Land sediments into a high resolution chronostratigraphic framework. Global paleosecular variation models are extremely useful for exploring the behavior of the geomagnetic field, as a dating tool for archeomagnetism and as a means for assessing the control of the geomagnetic field on radiocarbon production. Despite broad utility, the models are only as good as the data from which they are derived and as of now there are very few records from the southern hemisphere. Moreover, no record obtained to date has the resolution of that achievable at Site U1357. Therefore, the proposed work has the potential to substantially improve the paleosecular variation models. This proposal will also contribute to the education of a post-doctoral scholar, Dr. Saiko Sugisaki. She sailed as a shipboard paleomagnetist on Expedition 318, although her training was in optically stimulated luminescence. Having spent several months intensively engaged in paleomagnetic research, and also having taking the online paleomagnetism class offered through Scripps (http://magician.ucsd.edu/∼ltauxe/sio247), she has decided to continue her education as a post-doctoral scholar in the paleomagnetic laboratory at Scripps. The PI is well known for outreach efforts to the broader community by conducting short courses, by making the textbook Essentials of Paleomagnetism available for free access, by conducting online, free access, courses and by making the PmagPy paleomagnetic software package open source. This proposal will provide partial support for these education/outreach activities