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11.
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. 相似文献
12.
A. S. Astakhov V. S. Markevich A. N. Kolesnik Rujian Wang V. V. Kononov M. S. Obrezkova A. A. Bosin 《Oceanology》2014,54(5):624-636
The study of the bottom sediments accumulated during the last 60–65 ka in the pockmark craters of the Chukchi Plateau in the Arctic Ocean showed that their composition and lithostratigraphy in general are similar to those of the background areas. A specific feature is the presence of sedimentary interlayers and horizons with signs of gravitational stirring, carbonate mineralization, and accumulation under H2S contamination conditions. The micropaleontological remains found in the pockmark sediments accumulated during the glacial periods are represented by redeposited species from Paleozoic, Mesozoic, and Cenozoic deposits, which are locally exposed in the pockmark walls. It was concluded that the pockmarks were formed under the influence of pulsed fluid flows. The present-day topography of the pockmarks was formed at the last stage of active defluidization (35?20 ka ago). 相似文献
13.
E. V. Verzhbitskii M. V. Kononov A. F. Byakov 《Journal of Volcanology and Seismology》2011,5(4):241-267
This paper contains a comparative analysis of the theoretical parameters involved in the subsidence of spreading ridges into
the asthenosphere: Reykjanes, Kolbeinsey, the Azores segment of the Mid-Atlantic Ridge, as well as the following aseismic
ridges: the Ninety East Ridge, Maldives, Hawaiian-Emperor, and Louisville ridges due to the influence of a mantle plume. We
conclude that the respective geodynamic processes involved in generating spreading ridges in the North Atlantic and the aseismic
ocean ridges due to hotspot action are similar. The main phases in the evolution of the Iceland region are substantiated using
geological and geophysical data and computer simulation. We discuss the Cenozoic tectonic evolution of the region, calculated
and plotted paleogeodynamic reconstructions of the North Atlantic Ocean in the hotspot system for 60, 50, and 20 Ma. 相似文献
14.
E. V. Verzhbitskii L. I. Lobkovskii M. V. Kononov A. F. Byakov 《Doklady Earth Sciences》2011,441(1):1587-1590
The geological time of the formation of Alpha-Mendeleev and Lomonosov ridges is determined in a broad range from the Late
Cretaceous to the Cenozoic. This does not allow researchers to have reliable insight into the evolution of the entire Amerasian
Basin, which is characterized by a high hydrocarbon potential. The genesis of these ridges is still under discussion. For
a more precise time assessment, the geothermal method, which is highly informative in the sense of lithospheric age, has been
applied. On the basis of numerical geothermal calculations, the formation time intervals were determined at 97–79 Ma for Alpha-Mendeleev
Ridge and at 69–57 Ma for Lomonosov Ridge; these ages conform to the geological-geophysical data and verify the fact that
these ridges belong to the eastern part of the Russian shelf zone. The formation time of the Alpha-Mendeleev and Lomonosov
ridges determined has allowed us to optimize the calculations and plate-tectonic reconstructions for the Amerasian Basin. 相似文献
15.
D. A. Ksenofontov Yu. K. Kabalov O. V. Kononov 《Moscow University Geology Bulletin》2013,68(5):305-309
The crystal structure of gearksutite, Ca and Al hydrofluoride CaAlF4(OH) · H2O, was refined using the Rietveld method with power diffraction data. The thermal stability of its crystal structure was studied for the first time using high-temperature XRD. Thermal XRD study of the mineral in the temperature range from 25 to 300°C revealed its stability to temperatures of 300-310°C. The mineral began to decay at temperatures greater than 300°C. The increase in the unit-cell parameters was established and the coefficients of thermal expansion were calculated. 相似文献
16.
A. A. Velichko O. K. Borisova A. N. Drenova E. M. Zelikson V. A. Klimanov Yu. M. Kononov 《地理信息系统科学与遥感》2013,50(1):11-27
The authors describe the evolution of a new field in cartography—the substantive basis of which is the preparation of a series of spatial reconstructions (climate, landscape components) of the past on the basis of principles of comprehensive mapping of contemporary geosystems. The paper investigates how such an approach may be used to assess the present status of landscapes from the perspective of their general evolution and assist in the formulation of long-range predictions. Translated by Edward Torrey, Alexandria, VA from: Izvestiya Akademii Nauk, seriya geograficheskaya, 1998, No. 5, pp. 30-43. 相似文献
17.
E. V. Verzhbitskii L. I. Lobkovskii A. F. Byakov M. V. Kononov 《Doklady Earth Sciences》2012,444(2):666-670
In order to specify the origin and evolution of the Alpha-Mendeleev and Lomonosov ridges, profiles of the bottom relief and crustal basement were made. Additionally, the coefficients characterizing the rate of subsidence of the crustal basement in different parts of the ridges for the last 25 Ma were calculated and the depth of the crustal basement prior to the beginning of subsidence in the Early Miocene was estimated. The calculation results were compared with the model of thermal subsidence of the Greenland-Iceland and Iceland-Faroe thresholds, which were also formed by plume-tectonic processes. A large dome rise of the basement was found in the central parts of the Alpha-Mendeleev and Lomonosov ridges. It was also found that the coefficients of thermal subsidence of the crustal basement in the central parts of the Alpha-Mendeleev and Lomonosov ridges are close to those for the Greenland-Iceland and Iceland-Faroe thresholds. It was shown that the depth of the crustal basement prior to the beginning of subsidence in the Early Miocene grew going outwards from the central parts of the ridges, analogous to the present-day pattern. All the information given above indicates the thermal origin of subsidence for the Alpha-Mendeleev and Lomonosov ridges starting from the Early Miocene and the substantial influence of the Arctic Plume on the genesis and evolution of these ridges. 相似文献
18.
Cenozoic geodynamics of the Bering Sea region 总被引：1，自引：0，他引：1
In the Early Cenozoic before origination of the Aleutian subduction zone 50–47 Ma ago, the northwestern (Asian) and northeastern (North American) parts of the continental framework of the Pacific Ocean were active continental margins. In the northwestern part, the island-arc situation, which arose in the Coniacian, remained with retention of the normal lateral series: continent-marginal sea-island arc-ocean. In the northeastern part, consumption of the oceanic crust beneath the southern margin of the continental Bering shelf also continued from the Late Cretaceous with the formation of the suprasubduction volcanic belt. The northwestern and northeastern parts of the Paleopacific were probably separated by a continuation of the Kula-Pacific Transform Fracture Zone. Change of the movement of the Pacific oceanic plates from the NNW to NW in the middle Eocene (50–47 Ma ago) was a cause of the origin of the Aleutian subduction zone and related Aleutian island arc. In the captured part of the Paleopacific (proto-Bering Sea), the ongoing displacement of North America relative to Eurasia in the middle-late Eocene gave rise to the formation of internal structural elements of the marginal sea: the imbricate nappe structure of the Shirshov Ridge and the island arc of the Bowers Ridge. The Late Cenozoic evolution was controlled by subduction beneath the Kamchatka margin and its convergence with the Kronotsky Terrane in the south. A similar convergence of the Koryak margin with the Goven Terrane occurred in the north. The Komandorsky minor oceanic basin opened in the back zone of this terrane. Paleotectonic reconstructions for 68–60, 56–52, 50–38, 30–15, and 15–6 Ma are presented. 相似文献
19.
20.
E. V. Verzhbitsky L. I. Lobkovsky M. V. Kononov A. F. Byakov 《Izvestiya Physics of the Solid Earth》2012,48(11-12):785-797
An insufficient number of dated native samples and indistinct magnetic anomalies in the Amerasian Basin prevent geophysicists from identifying the exact age of most of its structural elements. Due to this, it is impossible to gain an insight into the evolution of this vast region, which is highly promising in terms of its hydrocarbon potential. Therefore, the geological time of the formation of the structural elements composing the Amerasian Basin is determined either hypothetically or very loosely (for example, Late Cretaceous-Cenozoic). In order to more precisely estimate the time of formation of the structural elements within the Amerasian Basin, we applied the geothermal method, which is highly informative in terms of the age of the lithosphere, its thickness, and the evolution of the basin structures. Besides, this method provides far narrower time constraints for the formation of the structures compared to the geological data. Based on the thermal flow data, we have numerically calculated the age of the structural elements composing the Amerasian Basin: Podvodnikov Basin (97?C79 Ma), Makarov Basin (75?C61 Ma), Alpha-Mendeleev Ridge (97?C79 Ma), and Lomonosov Ridge (69?C57 Ma). The age of these structures derived from the geothermal data agrees with the estimates determined from the geological, geomagnetic, seismic, and radiometric data. Based on the age of the structures estimated from the thermal flow data and the analysis of the geological and geophysical evidence, conclusions are made concerning the genesis and character of formation of the Podvodnikov and Makarov basins and the Alpha-Mendeleev and Lomonosov ridges within the Amerasian Basin. 相似文献