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11.
Maps of the principal structures and geological-geophysical knowledge for the Azores-Gibraltar and Icelandic regions have
been made. The geodynamic conditions of the Azores archipelago formation have been analyzed. It has been noted that the uplifting
of the Azores plume (as well as the Icelandic one) might have been triggered by near-surface tectonic processes. The computer
modeling has been performed with respect to the coefficients of the geodynamic sinking rates for the Azores fragment of the
Mid-Atlantic Ridge. Based on the modeling results, this rate was ∼1.5 times higher than the average sinking rate for the mid-ocean
ridges of the World Ocean in general. The high sinking rate of the Azores fragment is caused by the influence of the plume
material on the sinking process. Based on the complex analysis of the seismicity, thermal flow, and seismic tomography data
distribution, as well as the implemented numerical calculations, the European (northern) part of the diffuse boundary between
the Eurasian and African plates has been identified for the first time. Along with the African (southern) boundary, it outlines
the identified by the authors West Mediterranean plate. 相似文献
12.
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 bathymetric 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. 相似文献
13.
E. V. Verzhbitskii M. V. Kononov A. F. Byakov O. V. Grinberg 《Izvestiya Physics of the Solid Earth》2010,46(10):872-882
Maps of the main structures and the degree of geothermal studies of the Azores-Gibraltar and Iceland regions are constructed.
Computer modeling of the coefficient of velocity of thermal subsidence into the asthenosphere of the Azores segment of the
Mid-Atlantic Ridge is performed. According to the results of modeling, this velocity exceeds the mean velocity of thermal
subsidence of the mid-ocean ridges of the world ocean by a factor of ∼ 1.5. The high velocity of subsidence of the Azores
segment of the ridge is caused by the influence of the hot substance of the plume on the process of subsidence. The distributions
of the heat flow in the Horseshoe basin, Alboran Sea, and southern part of the Iberian Peninsula are analyzed. A zone of increased
heat flow and seismicity, extending from the Madeira-Torre Ridge through the Horseshoe basin, and farther to the east through
the southern parts of Spain and France, is identified for the first time. The identified geothermal zone marks the northern
branch of the diffuse boundary between the Eurasian and African plates. In the region of the Alpine chain, this zone joins
the southern boundary between the Eurasian and African plates, which runs along the northern part of Africa and the Apennine
Peninsula. The European and African plate boundaries outline the identified Western-Mediterranean plate, which mainly consists
of the oceanic and thinned continental lithospheres of the Algerian-Provence and Tyrrhenian basins. 相似文献