A Towed Electromagnetic Survey Across the Kane Megamullion: Mapping the Uppermost Gabbro/Serpentinite Contact

穿越凯恩巨型竖井的拖曳电磁勘探：绘制最上面的辉长岩/蛇纹岩接触面

• 批准号: 0823820
• 负责人: Robert Evans
• 金额: $ 18.66万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-01-01 至 2010-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0823820&HistoricalAwards=false
• 关键词: Towed; Electromagnetic; Survey; Across; Kane

Intellectual Merit: Oceanic core complexes (OCC) are widespread features along the mid-Atlantic Ridge and other slow and ultra-slow spreading ridges. They are often found in inside corners of ridge discontinuities, and recently have been observed to occur in clusters over large areas of the seafloor. Sampling of these structures has shown that they are low-angle detachment faults exposed at the seafloor that unroof and expose sections of lower crust and mantle. These faults accommodate large amounts of deformation through effective strain accumulation over periods of time, sometime in excess of 1 Myrs. The uplift and exposure of mantle peridotite is inherent to the uplift process. The presence of shallow peridotite promotes serpentinization across the features that, in at least one instance, results in moderate temperature hydrothermal venting fueled by exothermic reactions associated with the serpentinization. Discrimination of serpentinite from gabbro is difficult on the basis of seismic velocities alone. We suggest electrical conductivity as an alternative approach to identifying serpentinite within OCCs. This project is a ?proof-of-concept? pilot experiment, towing a seafloor EM system across the Cain and Abel domes within the OCC south of the Kane transform fault on the Mid-Atlantic Ridge. This will test our ability to discriminate, on the basis of electrical conductivity: a) the uppermost (~0-30m) contact geometry (laterally) between serpentinite and gabbro across the dome of the mound; and b) the variations in the nature and geometry of the fault core that accommodates most of the strain during plate separation. This experiment will be the first of its kind.Broader Impacts: This project marks the start of an international collaboration between the P.I. and scientists at IPGP in Paris. We anticipate a number of joint activities that will include seeking funds for the PI to spend time in Paris, and for Paris colleagues to visit WHOI. The data set collected in this pilot study will be appropriate for a small general examination project or as a project for a summer student fellow. WHOI runs a summer student program which annually brings around 20 students for 12 weeks and exposes them to their own research project and to a wide range of educational experiences. Many of these students go on to graduate school. The institution also supports and runs a minority trainee program which seeks to expose students from underrepresented backgrounds to ocean science. If appropriate candidates apply, then a summer student could come from this pool.

智力优势：海洋核心复合体（OCC）是大西洋中脊和其他缓慢和超缓慢扩张的海脊的广泛特征。它们经常出现在海脊不连续处的内角，最近观察到它们在海底大面积区域成簇出现。对这些结构的采样表明，它们是暴露在海底的低角度滑脱断层，使顶部和下地壳和地幔部分暴露出来。这些断层通过一段时间内的有效应变积累来容纳大量变形，有时超过 1 Myrs。地幔橄榄岩的隆起和暴露是隆升过程所固有的。浅橄榄岩的存在促进了整个特征的蛇纹石化，在至少一种情况下，导致由与蛇纹石化相关的放热反应推动的中等温度热液喷发。仅根据地震速度很难区分蛇纹岩和辉长岩。我们建议将电导率作为识别 OCC 内蛇纹岩的替代方法。该项目是一个“概念验证”项目？试点实验，将海底电磁系​​统拖过大西洋中脊凯恩转换断层以南 OCC 内的凯恩和阿贝尔圆顶。这将测试我们根据电导率区分的能力：a) 横跨土丘圆顶的蛇纹岩和辉长岩之间最上面（~0-30m）的接触几何形状（横向）； b）在板块分离过程中容纳大部分应变的断层核心的性质和几何形状的变化。该实验将是此类实验中的第一个。 更广泛的影响：该项目标志着 P.I. 之间国际合作的开始。以及巴黎 IPGP 的科学家。我们预计将开展一系列联合活动，其中包括为 PI 在巴黎逗留以及为巴黎同事访问 WHOI 寻求资金。本试点研究中收集的数据集适用于小型一般考试项目或夏季学生项目。 WHOI 开展暑期学生项目，每年招收约 20 名学生为期 12 周，让他们接触自己的研究项目和广泛的教育经历。其中许多学生继续读研究生。该机构还支持并运行一个少数族裔实习生计划，旨在让来自弱势背景的学生接触海洋科学。如果合适的候选人申请，那么暑期学生就可以从这个人才库中脱颖而出。