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.

知识价值：2010年12月12日，IODP远征330队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一个主要目标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，并与夏威夷热点在这段时间内观测到的15°位移进行比较。这些数据，连同详细的辐射年龄，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来自对方位无取向岩心样品的详细退磁研究。此外，我们将部署Göttingen井眼磁强计（GBM）进行三分量井眼磁测量。GBM的主要好处是，光纤陀螺可以确定完全定向的分量磁异常，并估计磁化偏角，有助于识别单个流动，并更可靠地估计热点和太平洋板块运动。测试表明，与GBM一起使用的下沉杆和扶正器都会产生大量的磁异常（在距离1m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下可能发生的变化，会影响磁测井的优势。因此，我们建议制造一种非磁性下沉棒，以便在远征330和随后的探险中精确地确定分量磁异常（和剩余赤纬）。8月份，现有下沉杆和扶正器的大磁特征被记录下来；在远征330开始之前的短时间内需要快速需要快速制造这个工具。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。提出的GBM磁测井有可能提供井内完全定向的矢量磁异常，显著增强了对路易斯维尔热点和太平洋板块过去运动的约束。一些考察队的参与者将参与解释井眼磁强计的结果，并将这些结果与回收的岩心材料的数据相结合。