Paleomagnetic Assisted Chronology of IODP Sites U1395 and U1396

IODP 站点 U1395 和 U1396 的古地磁辅助年代学

• 批准号: 1260671
• 负责人: Robert Hatfield
• 金额: $ 18.97万
• 依托单位: Oregon State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-05-01 至 2016-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1260671&HistoricalAwards=false
• 关键词: Paleomagnetic; Assisted; Chronology; IODP; Sites

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.

该提案旨在利用IODP勘探期间在蒙特塞拉特近海钻探的岩心，为1395和1396号站点制定古地磁年代学。340.岩芯为半远洋沉积物，夹火山灰/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号地点为1.1 MY（9厘米/千年），1396号地点为4.5 MY（3厘米/千年）。记录上级现存的陆地和海洋记录。两个地核都记录了磁反转：1395年4次，1396年17次。用于研究的U形通道样品已在手，储存在俄勒冈州圣4摄氏度的核心（伪单畴铁磁颗粒）的磁性是？理想？用于记录磁场行为和古强度。建议的工作包括：1.建立详细的磁年代学。解卷积测量，进行高精度测量，在反转间隔进行高分辨率RPI。对同一岩心进行年代学对比、O同位素对比和Ar-Ar对比。利用火山和半远洋沉积物的不同磁性来识别和记录火山灰层。灰岩年代学尝试确定火山灰的来源，例如不同的岛屿火山有不同的熔岩成分和磁性。将磁性与粒度、风化历史等联系起来。3.其他。会寻找撒哈拉沙漠的尘埃。记录的长度提供了检查地磁场行为的机会。该工作将通过创建1395和1396的复合拼接记录来完成，以帮助U通道工作的样本选择。将对样本进行逐步退磁，并在cm尺度下测量NRM。MS、ARM和XPS将用于识别磁性矿物。该信息将用于开发RPI的代理。选定的样品将被分解，以确定磁性矿物的颗粒大小特性，并将其与环境记录联系起来。更广泛的影响：该项目将直接支持俄勒冈州立大学的博士后研究助理和一名本科生，他们将接受测量，数据处理和古地磁数据解释的培训。将通过MAGIC数据库向研究界提供完整的数据集。