Multidisciplinary Studies

Although the emphasis on research at ocean ridges over the past 4 years has been on multi-disciplinary approaches, at the time of this report, truly multidisciplinary studies are just beginning to reach publication stage. Michael et al. [1994] presented a multidisciplinary study of the mid-Atlantic ridge at 31-34S that integrates topographic, gravity, and geochemical data to investigate the dynamic evolution of this segment of the MAR. This segment displays ridge crest anomalies including shallowing by 1500 m, the near-disappearance of the axial valley, the occurrence of a prominent bullseye gravity low centered over the shallow summit, and spikes in the incompatible element and radiogenic isotope ratios centered on the summit. Michael et al. [1994] used the combined geochemical and geophysical evidence to infer that the ridge-crest anomalies are related to interaction of the ridge with a passively embedded chemical heterogeneity in the mantle. Barth et al. [1994] combined reflection seismic, photographic, geochemical, and sea-floor imaging data to study the origin of bathymetric highs at ridge-transform intersections (RTI), using the Clipperton fracture zone as a study area. Their results suggest that the RTIs at the Clipperton fracture zone are maintained by the constant interplay between intruding ridge magma and the disrupting transform fault motion.