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11.
G. A. Avanesov I. V. Polyansky B. S. Zhukov A. V. Nikitin A. A. Forsh 《Izvestiya Atmospheric and Oceanic Physics》2013,49(9):1057-1068
The multispectral satellite imaging system (MSIS) aboard the Meteor-M No. 1 spacecraft (SC) has surveyed the territory of Russia and neighboring countries in three-bands of the visible and near-IR ranges with a resolution of 60/120 m in a swath of more than 900 km for three years. The MSIS data, supple-mented by synchronous navigational information, are automatically received, pipeline processed, archived, and cataloged at ground-based receiving stations in Moscow, Novosibirsk, and Khabarovsk. These data are used to solve a wide range of land-use, environmental, and emergency monitoring problems; assess ice situations in seas, rivers, and lakes; etc. The further development of imaging instruments for operational monitoring is aimed at increasing its resolution to 20–30 m in a simultaneously expanded swath of 1600–1800 km, allowing for imaging of most of the territory of Russia with inter-orbit overlapping. 相似文献
12.
Polyansky O. P. Korobeynikov S. N. Babichev A. V. Reverdatto V. V. Sverdlova V. G. 《Doklady Earth Sciences》2009,429(1):1380-1384
A new point of view describing processes of partial melting and development of gravitational instability in a thickening crust
with increased thickness of the granite layer is suggested. Numeral experiments support the following main conclusions. The
critical volume of partially melted material should be formed for the beginning of flotation in a gravitational field. Due
to model estimations, the height of the melting area in the granite crust should be not less than 6–7 km. A mushroom-shaped
form of the floating body was observed in all models regardless of the thermal source size (fixed or variable width): the
high temperature channel (magma leader) and head body of the diapir are formed. The height of diapir floating depends on rheological
features of the surrounding crust: 10 times increase in the yield strength (from 1 to 10 MPa) while temperature decrease confines
the possible level of rising to a depth of 15–16 km. An elevation of about 750 m is formed in the day surface relief above
the axis part of the diapir. 相似文献
13.
This is a critical comment on the model of basin formation by eclogitization of mafic crust suggested by E. Artyushkov. The eclogitization model bears uncertainties in average parameters (thickness, density, pressure) of lithospheric mantle, crust, and sediments, which may bias the estimates of subsidence magnitude. Main pitfalls, however, lie in high-pressure petrology: The lithostatic pressure is insufficient for eclogite to form in the lower crust beneath deep basins. It is shown that linear extrapolation of laboratory data on the gabbro-to-eclogite transition onto the field of relatively low pressures and temperatures in the lithosphere is incorrect. The hypothesized role of hot mantle fluids in the gabbro-eclogite transformation appears doubtful in terms of both petrology and kinetics of metamorphic reactions. Eclogite volumes in none of well known eclogitic sites agree with those required for eclogitization-driven subsidence. Artyushkov’s criticism of the extension basin formation model is not quite just. There are recent models of a two-layer lithosphere that imply a possibility of brittle and ductile deformation at different crust rheologies. The models we refer to predict most of extension to occur in mantle lithosphere rather than in the crust, this extension being able to produce deep continental basins. 相似文献
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O.P. Polyansky V.P. Sukhorukov A.V. Travin I.G. Alekhin D.S. Yudin 《Russian Geology and Geophysics》2011,52(9):991-1006
Based on the new petrological and thermochronological data, analysis of the metamorphism conditions and tectonic evolution of the Bodonchin zonal complex in the Mongolian Altay was performed. Using mineral geothermometers and geobarometers, the parameters of the thermal state of the Mongolian Altay crust site during the collision of terranes were estimated, and the paleogeotherm at the peak of syncollisional metamorphism was reconstructed. The thermal state of the crust was determined by either a high concentration of radioactive heat sources or a high mantle heat flow. The estimated metamorphism temperatures and pressures of rocks in two zones (staurolite-kyanite schists and migmatites) of the Bodonchin complex correspond to the paleogeotherms with average temperature gradients ∂T/∂z = 25.5 and 27.2 ºC/km. The results of isotope dating of zircons and metamorphic minerals were used to construct a thermochronological model for the regressive stage of evolution of the polymetamorphic complex. The rates of the ascent of metamorphic rocks to the surface as a result of thrusts in the Bulgan Fault zone were estimated at 0.3–1 mm/year. 相似文献
16.
Alan J. Hewitt Natasha Doss Nikolai F. Zobov Oleg L. Polyansky Jonathan Tennyson † 《Monthly notices of the Royal Astronomical Society》2005,356(3):1123-1126
HDO and D2 O are thought to be present in significant quantities in the coldest regions of the Universe. Partition functions are calculated for these species and used to calculate temperature dependent equilibrium constants for the most important fractionation reactions involving water. HDO may also be a key indicator of the absence of deuterium burning in very low mass stars. The HDO partition function calculation is extended to high ( T ≤ 6000 K) temperatures for this purpose. 相似文献
17.
Deformation patterns in subduction zones, feeder systems of volcanoes, and rifts are compared and investigated in terms of relations among elastoplastic strain, rheology, pore fluids, and temperature. Regional-scale subduction processes have been explored in segments of the Kuriles–Kamchatka, Izu-Bonin, and Mariana zones. Slab geometry constraints from the 3D velocity structure are used to model the balance of forces in the three subduction zones and to distinguish the regions of predominant push or pull. Stress and strain variations in suprasubduction crust are considered for the case of magma sources beneath the Klyuchevskoy group of volcanoes. Time-lapse (4D) seismic tomography shows crustal magma reservoirs to appear and disappear rapidly as the volcanoes become active or dormant, respectively. This behavior is due to rapid strain changes which cause fast flow of fluids and the ensuing decrease or increase of melting temperature in the magma reservoirs. In addition to subduction zones, stress–strain patterns are modeled for collisional (compressive) settings, with the example of the Altai–Sayan area and the Caucasus, and for the conditions of rifting (extension), in the case of the Vilyui basin. As the modeling shows, formation of a superdeep basin does not necessarily require the crust to stretch twice or more: only 20% stretching in the necking region is enough to produce a 10–15 km deep basin. 相似文献
18.
Evidence from Fe- and Al-rich metapelites for thrust loading in the Transangarian region of the Yenisey Ridge, eastern Siberia 总被引：1，自引：0，他引：1
I. I. Likhanov O. P. Polyansky V. V. Reverdatto I. Memmi 《Journal of Metamorphic Geology》2004,22(8):743-762
In the Transangarian region of the Yenisey Ridge in eastern Siberia (Russia), Fe‐ and Al‐rich metapelitic schists of the Korda plate show field and petrological evidence of two superimposed metamorphic events. An early middle Proterozoic event with age of c.1100 Ma produced low‐pressure, andalusite‐bearing assemblages at c. 3.5–4 kbar and 540–560 °C. During a subsequent late Proterozoic event at c. 850 Ma, a medium‐pressure, regional metamorphic overprint produced kyanite‐bearing mineral assemblages that replaced minerals formed in the low‐pressure event. Based on the results of geothermobarometry and P–T path calculations it can be shown that pressure increased from 4.5 to 6.7 kbar at a relatively constant temperature of 540–600 °C towards a major suture zone called the Panimba thrust. In order to produce such nearly isothermal loading of 1–7 °C km ?1, we propose a model for the tectono‐metamorphic evolution of the study area based on crustal thickening caused by south‐westward thrusting of the 5–7 km‐thick upper‐plate metacarbonates over lower‐plate metapelites with velocity of c. 350 m Myr?1. A small temperature increase (up to 20 ± 15 °C) of the upper part of the overlapped plate is explained by specific behaviour of steady‐state geotherms calculated using lower radioactive heat production of metacarbonates as compared with metapelites. The suggested thermal‐mechanical model corresponds well with P–T paths inferred from obtained thermobarometric data and correlates satisfactorily with P–T trajectories predicted by other two‐dimensional thermal models for different crustal thickening and exhumation histories. 相似文献
19.
The Connemara region of the Irish Caledonides is a classic example of regional-scale metamorphism of low pressure and high temperature. This terrane is considered as part of a fold belt comprising metasedimentary and metavolcanic rocks that are correlated with the Neoproterozoic–Lower Paleozoic Dalradian Supergroup of Scotland. In mid-Ordovician time, the extensive and high-temperature metamorphism was superimposed on the Dalradian rocks resulting in the Connemara zoning. The key feature of the zoning is elevated horizontal thermal gradient of ca. 14 °C/km. Geological data and geochronological evidence point to a causative link between metamorphism and associated magmatic intrusions, and a brief period of development for the metamorphic zoning. Magmatic intrusion into the middle part of continental crust is treated as a most plausible source of heat for metamorphism, and other conjectures as to the origin of the zoning (flow of hot fluid through the permeable rocks, fracture conduit flushed by flowing magma) are believed to be improbable. To examine in sufficient detail the problem of the nature of heat source, a series of appropriate calculations have been performed to reach the best agreement between the observed and simulated spatial distribution of maximum temperatures at different times. The mathematical modelling shows that the temperature–spatial structure of the Connemara zoning is best explained by the model version based on mid-crustal heating above the upper contact of magmatic intrusive body gently curved and tilted at an angle between 20° and 40°, with an initial temperature of the magma appropriate to a basaltic melt. The model estimate of total lifetime of the temperature anomaly in the crust is of the order of 5–6 Ma. In general, this is in rather good agreement with the currently available evidence of geochronological duration of metamorphism and magmatism in Connemara. 相似文献
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