Genesis of Shatsky and Hess Oceanic Rises in the Pacific Ocean As Deduced from Geologic-Geophysical Data and Numerical Modeling

摘要

The geologic structure and distribution of geophysical fields in the area of the Shatsky and Hess rises are considered. The ages of the Shatsky and Hess rises estimated at ～140 and ～100 Ma, respectively, from heat-flow parameters are consistent with the ages determined from magnetic measurements. The calculated thickness of the lithosphere beneath the rises (80-90 km) is close to that of the adjacent plates of the oceanic framework. This indicates that the rises were formed near the spreading axis. It is suggested that the rises evolved as autonomous structural features and their evolution followed the crystallization model of the oceanic-bottom formation. The tectonic analysis of the North Pacific has been carried out, and a geodynamic model of the growth of the Shatsky and Hess rises 140-83.5 Ma ago has been proposed. According to this model, the rises originated at the triple junction. This result is supported by the parameters of heat flow. The geothermal and geodynamic data and results of numerical modeling suggest that the origin of the Shatsky and Hess rises is related to plume tectonics.