NONLINEAR DEPENDENCE OF THE RATE OF STRUCTURE GENERATION ON THE RATE OF SPREADING IN OCEAN RIFT ZONES

Abstract

In recent years, detailed investigations with equipment such as unmanned and manned submersibles have provided new data that can be used to make the first quantitative estimates of the rate of structure formation at various rates of plate separation. Detailed bathymetric and tectonic charts and seafloor profiles, obtained from underwater geophysical surveys in seven areas on the crests of mid-ocean ridges in the Atlantic and Pacific oceans, were used to derive such measures. Together, the available data on seafloor morphology, geophysical anomalies, and the structure of the sedimentary sequence of ocean rift zones indicate that the dominant factor generating their morphostructure is uplifting of asthenospheric material and the type of its viscous flow. Our estimates of the rate of structure generation are generally consistent with this qualitative model.