Magnetostratigraphy and Rock Magnetism of Expedition 318 Sediments

智力价值1月份IODP远征318的总体目标是什么？2010年3月(惠灵顿？霍巴特)的目标是：1)确定冰到达威尔克斯陆缘的时间，2)确定从湿冰川向冷冰川过渡的性质和年代，3)获得新近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)通过在阿德埃利盆地钻探获得全新世的超高分辨率记录。IODP探险318钻探了7个地点，采集了2500米的下始新世至全新世沉积物。318号探险规定的目标的一个关键方面是记录沉积物和沉积间断的年龄。初步的磁性地层数据为南大洋的生物地层学提供了关键的制约和校准，因为那里的直接校准明显很少。例如，在ODP189航次期间从塔斯马尼亚共轭边缘钻探的岩芯发现了类似年龄的沉积物，但到目前为止，古近纪部分的磁性地层学不足以校准地质年表。来自Expedition318沉积物的磁性组构、矿物学和粒度信息为记录在这一独特沉积序列中的环境变化提供了有趣的线索。IODP探险318的另一个主要目标是通过在阿德埃利盆地钻探获得全新世的超高分辨率记录，阿德埃利盆地是一个190米厚的硅藻质软泥序列，覆盖在冰川直径上，年龄为11ka。U1357站点揭示了第一个来自南大洋的海洋和气候变异性的年度分辨时间序列。从U1357A档案一半的船上测量获得的数据记录了无与伦比的地磁场长期变化(SV)记录，这不仅有望创造史无前例的SV记录，还将为孔与孔之间的关联提供关键约束。这项提案要求提供资金，对探险318钻探获得的材料进行古地磁和岩石磁学分析。它还寻求适度的资金，用于对在ODP189航次期间钻探并存放在日本高知储存库的岩芯进行采样和分析。广泛影响通过氧同位素值汇编及其与推断的大气二氧化碳的关系揭示的新生代冰川历史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，其历史因此在当前的气候变化辩论中发挥着重要作用。这项拟议的工作对于将威尔克斯陆地沉积物置于高分辨率年代地层框架中至关重要。全球古分子变化模型对于探索地磁场的行为、作为古地磁的年代测定工具和评估地磁场对放射性碳生产的控制是非常有用的。尽管这些模型具有广泛的实用性，但它们的好坏取决于它们所依据的数据，而且到目前为止，来自南半球的记录很少。此外，到目前为止，还没有获得的记录具有在U1357站点可以实现的解决方案。因此，这项拟议的工作有可能大幅改进古分子变化模型。这项提议还将有助于博士后学者杉崎赛子博士的教育。她作为一名船上的古地磁学家在318号远征中航行，尽管她的训练是在光学刺激发光下进行的。在花了几个月的时间专注于古地磁研究，并参加了斯克里普斯(http://magician.ucsd.edu/&amp；#8764；ltauxe/sio247)，提供的在线古地磁学课程后，她决定继续在斯克里普斯的古地磁实验室从事博士后研究。通过举办短期课程、免费提供教科书《古地磁学概论》、在线免费提供课程以及使PmagPy古地磁软件包开放源码，PMagPy古地磁软件包向更广泛的社区推广，这是众所周知的。这项提议将为这些教育/外联活动提供部分支持。

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