Contributions of mGal - Accuracy Gravity to Studies of Oceanic Spreading Centers and the RIDGE 2000 Program Donna

The RIDGE2000 program (R2K) is designed to further understanding of the geophysical, geochemical and geobiological causes and consequences of energy and material transfer, from the Earth’s mantle to the hydrosphere and biosphere, along the globe-encircling mid-ocean ridge system. Three sites on the ridge are the focus of detailed R2K studies that will integrate information at various scales to determine how processes below the seafloor are linked to seawater circulation and life within and just above the uppermost crust. A key question is how the morphology of the spreading center axis is related to the supply of magma at depth and the vigor of hydrothermal circulation that vents at the seafloor. Several models suggest that axial morphology is a function of crustal structure and thicknessgeophysical parameters that are reflected in the gravity field. The proposed higher resolution satellite gravity mission would provide new global constraints on how crustal production may vary along and between segments of the mid-ocean ridge system. Coverage on the young flanks of the ridge will enable temporal characterization of how crustal production and tectonism evolves over time at each segment. The global perspective of mGal-accuracy satellite gravity along the spreading centers and young flanks would provide key context within which the detailed R2K results are interpreted. In addition, the ~15 km resolution would allow first-order quantitative analyses to be made that address fundamental problems such as the origin of ridge segmentation and the time/length scale of variability in magma supply to spreading centers.