RAPID: A Nonmagnetic Sinker Bar for Magnetic Logging on IODP Expedition 330

RAPID：用于 IODP Expedition 330 磁测井的非磁性沉降片

• 批准号: 1106464
• 负责人: Jeffrey Gee
• 金额: $ 1.8万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-12-01 至 2011-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1106464&HistoricalAwards=false
• 关键词: RAPID; Nonmagnetic; Sinker; Bar; Magnetic

Intellectual Merit: IODP Expedition 330 to the Louisville Seamounts starts 12 December 2010 from Auckland, New Zealand. A primary objective of drilling at the Louisville volcanic chain is to document the possible motion of the Louisville hotspot between 80 and 50 Ma. High quality paleomagnetic data are required to document this motion and to compare with the 15° shift observed for the Hawaiian hotspot over this time interval. These data, together with detailed radiometric ages, will provide the basis for calibrating and testing various geodynamic models.The most robust paleolatitude information will be derived from detailed demagnetization studies of the aziumuthally-unoriented core samples. In addition, we will deploy the Göttingen Borehole Magnetometer (GBM) to make 3-componentmagnetic borehole measurements. The main benefit of the GBM is that fiber-optic gryos should allow fully oriented component magnetic anomalies to be determined and magnetization declination to be estimated, facilitating identification of individual flows and a more robust estimate of hotspot and Pacific plate motions. Tests reveal that the sinker bar and centralizer to be used with the GBM both generate substantial magnetic anomalies (up to 10,000 nT at a distance of 1m). These large signals, and importantly the likely changes in these signals on different deployments, compromise the benefits of the magnetic logging.We therefore propose fabrication of a nonmagnetic sinker bar that will allow determination of accurate component magnetic anomalies (and remanent declinations) on Expedition 330 and subsequent expeditions. The large magnetic signature of the existing sinker bar and centralizer were documented in August; the short time before Expedition 330 begins requires rapid requires rapid fabrication of this tool.Broader Impacts: High quality paleomagnetic and age data are required to document the motion of the Louisville hotspot, a primary goal of Expedition 330. The proposed GBM magnetic logging has the potential to provide fully oriented vector magnetic anomalies in the borehole, significantly enhancing the constraints on the past motion of the Louisville hotspot and Pacific plate motion. A number of Expedition participants will be involved in interpretation of the borehole magnetometer results and integrating these results with data from the recovered core material.

智力优势：IODP 330 号探险队于 2010 年 12 月 12 日从新西兰奥克兰出发前往路易斯维尔海山。在路易斯维尔火山链钻探的主要目的是记录路易斯维尔热点在 80 到 50 Ma 之间可能的运动。需要高质量的古地磁数据来记录这一运动，并与在此时间间隔内观察到的夏威夷热点的 15° 偏移进行比较。这些数据与详细的辐射年龄一起，将为校准和测试各种地球动力学模型提供基础。最可靠的古纬度信息将从对方位无向岩心样本的详细退磁研究中得出。此外，我们将部署哥廷根钻孔磁力计 (GBM) 进行三分量磁性钻孔测量。 GBM 的主要优点是光纤陀螺仪可以确定完全定向的磁异常分量并估计磁化偏角，从而有助于识别单个流以及对热点和太平洋板块运动进行更可靠的估计。测试表明，与 GBM 一起使用的沉降片和扶正器都会产生大量的磁异常（在 1m 距离处高达 10,000 nT）。这些大信号，以及重要的是这些信号在不同部署中可能发生的变化，损害了磁测井的优势。因此，我们建议制造非磁性沉降片，以便在 Expedition 330 和后续探险中确定准确的分量磁异常（和剩磁偏角）。 8 月份记录了现有沉降片和扶正器的大磁性特征；远征 330 开始前的短时间内需要快速制造该工具。更广泛的影响：需要高质量的古地磁和年龄数据来记录路易斯维尔热点的运动，这是远征 330 的主要目标。拟议的 GBM 磁测井有可能在钻孔中提供完全定向的矢量磁异常，显着增强对路易斯维尔热点和太平洋过去运动的约束 板块运动。许多探险参与者将参与对钻孔磁力计结果的解释，并将这些结果与回收的岩心材料的数据相结合。