Evolution of Overlapping Spreading Centers: A SeaMARC II Investigation.

摘要

During a major SeaMARC II expedition in May-June 1987 we mapped all the overlapping spreading centers (OSCs) north of the equator, between 8 and 18 deg N, and all their related off-axis scars. With this areal coverage of sidescan sonar and bathymetric data we document the current status and the evolutionary path of these discordant zones over the last one million years. The collection of this coverage high resolution sonar data allows us to characterize zones of normal and anomalous bottom roughness, which can be related to the near-axis geological processes which created them. We have completed the following tasks: (1) complete analysis of tectonic and magnetic data for the 11 deg 45'N survey (11 deg 20'N to 12 deg 30'N); (2) the nature of faulting on mid-ocean ridges based primarily on SeaMARC II data from our ONR cruise; (3) creation of final 50 m contour interval maps for 8 -18 deg N merging SeaMARC II data with existing Sea Beam data. Also included is a reprint entitled 'The Mid-Ocean Ridge'. Keywords: Seafloor spreading; Ocean ridges; Faults geology. (EDC)