摘要：

The mid-ocean ridge (MOR) system is not uniform. Systematic changes in depth and shape subdivide the ridge into discrete spreading segments. It is not well understood how such morphological changes develop, but this spatial diversity is probably a result of variations in magma supply. Recent observations of ridge bathymetry (Carbotte et al. Nature, 2004) indicate magmatic segmentation at fast and intermediate spreading centers is linked to the migration velocity (rate and direction) of the spreading axis over the mantle. In this investigation, inter-segment elevation changes are examined within the context of absolute plate motions, with particular emphasis on slow-spreading MORs. Multibeam bathymetry data from the slow-spreading Mid-Atlantic Ridge (MAR 22-36 deg N and 25-35 deg S latitude) is used to inspect the relationship between the direction of ridge migration and various morphological ridge characteristics. Moving averages, with swaths of varying widths, smooth the axis depth in order to eliminate local topographic anomalies. For each first- and second- order segment, the axial depths of the segment's ends and midpoint, as well as average depth, are measured and compared across transform faults (TFs) and non-transform offsets (NTOs). These values are compared as a function of distance from each TF or NTO. At fast and intermediate spreading centers Carbotte et al. observed that leading segments, whose offsets are in the direction of ridge migration, are typically shallower and morphologically robust, relative to trailing segments. Our preliminary results along the MAR suggest a weak correlation in the slow spreading environment.

展开