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

Woods Hole Oceanographic Institution, Woods Hole MA

Investigators

Abstract

Abstract of Tivey 0118445 The 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.