Paleomagnetic Assisted Chronology of IODP Sites U1395 and U1396

这项提议寻求利用IODP Exp期间在Monserrat近海钻探的岩芯来开发1395和1396站点的古地磁年代学。340.岩心为半深海沉积物，夹层有火山灰和浊积岩。这些岩芯提供了沉积和火山活动的连续记录，1395站(9厘米/年)为1.1My，1396站(3厘米/年)为4.5My。记录优于现存的陆地和海洋记录。两个地核都记录了磁反转；1395年有4个，1396年有17个。用于研究的U沟道样品在俄勒冈州圣彼得堡4℃保存，磁芯(伪单磁区铁磁颗粒)的磁性能是理想的？用于记录磁场行为和古强度。建议的工作包括：1.制定详细的磁力年代学。反卷积测量，进行高精度测量，在反转间隔进行高分辨率RPI。年代学将与同一岩心上的氧同位素和Ar-Ar工作相关联。2.环境和地层工作。利用火山岩和半深海沉积物的不同磁性来识别和记录火山灰岩层。花色年代学。尝试确定火山灰的来源，例如，不同的岛屿火山具有不同的熔岩成分和磁性。将磁性与颗粒大小、风化历史等联系起来。将寻找撒哈拉尘埃。记录长度提供了检查地磁场行为的机会。这项工作将通过创建1395和1396的复合拼接记录来完成，以帮助U形通道工作的样品选择。样品将逐渐退磁，并以厘米为单位测量NRM。将使用MS、ARM和IRM来识别磁性矿物。此信息将用于开发RPI的代理。选定的样品将被分解，以确定磁性矿物的粒度特性，并将其与环境记录联系起来。布罗德影响：该项目将直接支持俄亥俄州立大学的一名博士后研究助理和一名将接受测量、数据处理和古地磁数据解释培训的本科生。完整的数据集将通过MAGIC数据库提供给研究界。

This proposal seeks to develop a paleomagnetic chronology for sites 1395 and 1396 using cores drilled offshore of Monserrat during IODP exp. 340. The cores are hemipelagic sediments intercalated with tephra/ash and turbidites. The cores provide a continuous record of sedimentation and volcanic activity, 1.1 MY for site 1395 (9 cm/kyear), 4.5 MY for site 1396 (3 cm/kyear). Records are superior to extant terrestrial and marine records. Both cores record magnetic reversals; 4 in 1395 and 17 in 1396. The U-channel samples for the study are in hand, stored at 4oC at Oregon St. The magnetic properties of core (pseudo-single domain ferromagnetic grains) are ?ideal? for recording magnetic field behavior and paleointensity. Proposed work includes:1.Develop a detailed magnetochronology. Deconvolute measurements, make high precision measurements, do high resolution RPI at reversal intervals. Chronology will be correlated with O isotope and Ar-Ar work on the same cores.2.Environmental and stratigraphic work. Use the differing magnetic properties of volcanic and hemipelagic sediments to identify and log tephra layers. Tephrochronology. Attempt to identify sources of tephra, e.g. different island volcanos have different lava compositions and magnetic properties. Relate magnetitc properties to grain size, weathering history etc.3.Other. Will look for Saharan dust. Length of record provides opportunity to examine behavior of geomagnetic field. The work will be accomplished by creation of a composite spliced record of 1395 and 1396 to aid in sample selection for U-channel work,. The samples will be progressively demagnetized and NRM measured at the cm scale. MS, ARM, and IRM will be used to identify magnetic minerals. This information will be used to develop a proxy for RPI. Selected samples will be disaggregated to determine particle size properties of the magnetic minerals and relate this to the environmental record.BROADER IMPACTS: This project will directly support a postdoctoral research associate at OSU and an undergraduate student who will be trained in measurement, data processing and interpretation of paleomagnetic data. The complete data set will be made available to the research community through the MAGIC database.