Evolution of the Lithosphere of the Hawaiian-Emperor Seamount Chain, Pacific Ocean, As Inferred from Geophysical Data

摘要

The analysis of geological and geophysical data on the Hawaiian-Emperor seamount chain indicates that the commonly assumed origin of its lithosphere is inconsistent with the geothermal model of the oceanic-bottom formation. To reveal the nature of the Hawaiian-Emperor Ridge, the main tectonic units of the North Pacific were thoroughly analyzed and a map of geothermal data, magnetic anomalies, and bottom age in this region has been compiled. The subsidence rate of the lithosphere that was thermally rejuvenated by plume material after the passing of the Pacific plate over the Hawaiian hot spot was calculated with the aid of the bathy-metric database for the World Ocean. The calculated parameters show that the lithosphere, which underwent thermal rejuvenation, subsides at a much lower rate than it spreads. The obtained empirical equation describes the abrupt uplifting and further subsidence of the oceanic floor during the passing of the Pacific Plate over the Hawaiian plume. The heat flow calculated in line with the thermophysical model of the thermally rejuvenated lithosphere is close to the heat flow measured at the surface of the Hawaiian-Emperor Seamounts. Thus, the proposed model is realistic. Paleogeodynamic reconstructions of the thermal regime during the formation of the Hawaiian-Emperor seamount chain were made in absolute coordinate system for the period 90-20 Ma on the basis of geological and geophysical data and the calculated distribution of bottom ages in the North Pacific.