Magnetic and Structural Study of Sub-Volcanic Oceanic Lithosphere Exposed in Kane Megamullion, Mid-Atlantic Ridge, 23deg30min N

拟建项目将研究凯恩巨型断层，该断层被解释为大西洋中脊凯恩断裂带附近一条长寿命正滑脱断层的下盘。断裂似乎暴露了地壳深处，可能还有上地幔，岩石圈的一部分，使其可以进行调查、取样和最终的钻探。拟议的现场计划将使用自主水下航行器（ABE）， ROV Jason和疏浚，以及实验室分析来解决以下问题：1)如何在地壳中部和更深层次记录地球磁场的磁化和极性反转历史？(2)裂谷轴的岩浆作用在什么条件下参与了巨型砾石的形成，由此形成的巨型砾石在中地壳和更深层次的组成和侵入关系是什么？3)洋壳大正断层剪切带应变调节的性质和应变局部化的演化特征是什么？这是一个独特的可进入的部分，在那里的调查和采样将允许对缓慢扩张的地壳的增生和解剖过程有重要的新见解。调查数据将提供数据，以扩展和限制钻探到数百万的解释，进入三维空间。

Abstract of Tivey 0118445The proposed project will study the Kane megamullion, which is interpreted to be the exhumed footwall of a long-lived normal detachment fault near the Kane Fracture Zone on the Mid-Atlantic Ridge. The faulting appears to have exposed a deep-crustal and possibly upper mantle, section of lithosphere, making it accessible to survey, sampling and eventual drilling. The proposed field program will use the autonomous underwater vehicle (ABE), ROV Jason and dredging, together with laboratory analyses to address the questions of 1) how are magnetization and polarity -reversal history of Earth's magnetic field recorded at mid-crustal and deeper levels?, 2) what conditions of magmatism at the rift axis attend formation of megamullions,and what are the resulting composition and intrusive relations at mid-crustal and deeper levels? and 3) what are the nature of strain accomodation and evolution of strain localization in the shear zone of a major normal fault in ocean crust? This is a uniquely accessible section where survey and sampling will allow significant new insights into the processes of accretion and dissection of slow-spreading crust. The survey data will provide data to extend and constrain interpretations from drilling into megamullions, into three dimensions.