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1.
Major hypotheses on the formation of the Iceland region are considered. It is noted that plate- and plume-tectonic genesis
is the most substantiated hypothesis for this region. Model estimations of the effect of hot plume on the formation of genetically
different oceanic ridges are obtained. Computer calculations are performed for the thermal subsidence rate of aseismic ridges
(Ninetyeast and Hawaiian-Emperor) in the asthenosphere of the Indian and Pacific oceans. Comparative analysis of the calculated
subsidence rates of these ridges with those in the Iceland region (Reykjanes and Kolbeinsey ridges) is performed. The results
suggest that the thermophysical processes of formation of the spreading Reykjanes and Kolbeinsey ridges were similar to those
of the aseismic Ninetyeast and Hawaiian-Emperor ridges: the genesis of all these ridges is related to the functioning of a
hotspot. Analysis of the heat flux distribution in the Iceland Island and Hawaiian Rise areas is carried out. Analysis and
numerical calculations indicate that the genesis of Iceland was initially characterized by the plume-tectonic transformation
of a continental rather than oceanic lithosphere. The level of geothermal regime near Iceland was two times higher (100 mW/m2) relative to the Hawaiian Rise area (50 mW/m2) because the average lithosphere thickness of the Reykjanes and Kolbeinsey ridges near the Iceland was approximately two
times less (40 km) relative to the thickness of the Pacific Plate (80 km) in the Hawaiian area. The main stages of evolution
of the Iceland region are based on geological and geothermal data and numerical thermophysical modeling. The Cenozoic tectonic
evolution of the region is considered. Paleogeodynamic reconstructions of the North Atlantic in the hotspot system at 60,
50, and 20 Ma are obtained. 相似文献
2.
The results of the bathymetry simulation indicate the emplacement of the Mesozoic Arctic plume into the lithosphere of the Alpha-Mendeleev and Lomonosov ridges. The study also presents a model of the thermal subsidence to the asthenosphere. The calculated coefficients are compared with those obtained for the Greenland-Iceland and Iceland-Faeroe ridges, which were formed in response to hotspot activity. It was shown that the coefficients of the thermal subsidence in the central part of the Alpha-Mendeleev and Lomonosov Ridges are similar to those calculated for the Greenland-Iceland and Iceland-Faeroe ridges. This indicates the thermal regime of the subsidence of the Alpha-Mendeleev and Lomonosov ridges since the Early Miocene and the increased influence of the Arctic plume on the ridge genesis. The ridges are interpreted to have formed over a broad geological timeframe, from the late Cretaceous to the Cenozoic. A geothermal method, which is highly informative in terms of the age of the lithosphere, provides better constraints on the timing of ridge formation. The age estimates for the Alpha-Mendeleev (97–79 Ma) and Lomonosov ridges (69–57 Ma) derived from the geothermal data allowed us to draw a convincing conclusion about the genesis of these ridges. 相似文献
3.
Natural oil and gas seeps on the Black Sea floor 总被引：3，自引：0，他引：3
R.?P.?KruglyakovaEmail author Y.?A.?Byakov M.?V.?Kruglyakova L.?A.?Chalenko N.?T.?Shevtsova 《Geo-Marine Letters》2004,24(3):150-162
Migration of hydrocarbons to the seafloor in the Black Sea occurs via direct seepages, mud volcanoes, and development of fluidized sediment flows (e.g., diapers). Gas migration occurs on the shelf, continental slope, and abyssal plain. Gas hydrates are spatially related to gas accumulations and are present in shallow subsurface sediment layers. Their distribution is controlled by the activity of mud volcanoes. In regions of methane seepages, specific biogeochemical processes related to the activity of methane-oxidizing bacteria are evident. This activity results in the formation of diagenetic minerals (carbonates, sulfides, sulfates, phosphates and other minerals). 相似文献
4.
5.
The geothermal and geomagnetic data on the Iceland region are mapped. On the basis of the analysis of geological, tectonic, geothermal, and geomagnetic data and on the information on the age and character of the volcanism at the European and Greenland rifting margins, the principal evolution stages of the Iceland region are substantiated. The modeling estimation of the rates of thermal subsidence of the Reykjanes and Kolbeinsey ridges and of the Greenland-Iceland and Iceland-Faeroes sills shows their more than 20% difference. The different rates of thermal subsidence of the structures are caused by various effects of hot matter of the mantle plume, its volume, and the different genesis of the lithosphere. The formation of the lithosphere of Iceland Island, besides the plate and plume tectonics, involved the thermophysical processes of the transformation of the lithosphere of continental genesis. This is confirmed by the analysis of the spreading rates, basalt age, and the data of the geochemical and isotope studies of volcanic rocks. The numerical modeling performed points to the presence of an additional heat source related to the plume hot matter in the Iceland region (Iceland Island, 30 mW/m2; the Reykjanes and Kolbeinsey ridges, 15 mW/m2), which conforms to the data of magnetotelluric geochemical studies. 相似文献
6.
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
7.
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
8.
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
9.
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
10.
Verzhbitsky E. V. Lobkovsky L. I. Kononov M. V. Byakov A. F. 《Izvestiya Physics of the Solid Earth》2012,48(11):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 (97–79 Ma), Makarov Basin (75–61 Ma), Alpha-Mendeleev Ridge (97–79 Ma), and Lomonosov Ridge (69–57 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