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The paper discusses the distinctive features of grain size distribution of permafrost soils formed under conditions of continental lithogenesis and cryogenic weathering of rocks. As a functional consequence of surface erosion of mineral particles, the log-normal distribution of the density function of grain size is derived confirmed for any conditions and sediment types.  相似文献   
2.
The tectonics and metallogeny of the junction zone between the North Asian craton and Pacific tectonic belt are considered. This zone is characterized by a wide variety of structures superposed on the metamorphic basement, which was formed in the course of a multistage geologic development of the craton from the Precambrian to the Cenozoic. They are related to the craton evolution and its response to the collision and subduction processes in the adjacent orogenic belt, processes in the passive and active continental margins, and plume magmatism. The geological structure of the region includes blocks of metamorphic rocks of the Aldan–Stanovoi shield, Paleoproterozoic volcanogenic troughs, Mesoproterozoic–Neoproterozoic and Early Paleozoic structures of the platform cover, Late Paleozoic volcanic and terrigenous troughs, structures of the Late Mesozoic Okhotsk–Chukotka volcanic belt of the active continental margin, and Late Cretaceous riftogenic structures formed in response to plume magmatism. In total, six metallogenic epochs are recognized in the development of ore mineralization: Archean–Early Paleoproterozoic, Late Paleoproterozoic, Mesoproterozoic, Neoproterozoic, Late Paleozoic, and Late Mesozoic. The minerageny of the junction zone between the craton and Pacific belt is highly diversified, being characterized by distinct evolution in time and space. Each development stage features its own set of mineral resources.  相似文献   
3.
New data on the age, composition, sources, and formation conditions of the Early Precambrian granitoids of the Batomga inlier of the southeastern Siberian Platform basement are discussed. Geochronological SRHIMP II U–Pb study of the zircons reveals that the calc-alkaline granitoids of the Khoyunda Complex are 2056–2057 Ma in age and their formation was related to the Early Proterozoic stage in the development of the Batomga granite–greenstone domain. It is established that the primary melts for these rocks formed in subduction settings through melting of the depleted mantle source with some contribution of ancient crustal material. In terms of temperature, partial melting followed by crystallization of the granitoids under peak metamorphic conditions corresponds to the transition between amphibolite and granulite facies at elevated pressure; high temperature and high-grade metamorphism are subduction-related phenomena reflected in the back-arc settings of the active continental margin. The protoliths of calc-alkaline metavolcanics of the Batomga Group are found to be chronologically and compositionally analogous to the subduction granitoids of the Khoyunda and Dzhagdakan complexes; i.e., these granitoids are coeval with the Batomga island arc. The lower age limit of the Batomga Group is estimated at 2.2 Ga and its upper age limit is defined by the age of the intruded Khoyunda granitoids. The formation of the rocks of the Batomga Group and associated granitoids of the Khoyunda and Dzhagdakan complexes reflects the formation of the continental crust at the Early Paleoproterozoic stage of the evolution of the Batomga lithosphere block (2.2–2.0 Ga ago).  相似文献   
4.
An analysis of spectra of wave disturbances with zonal wave numbers 1 ≤ k ≤ 10 is carried out using winter (November to March) ERA-Interim reanalysis geopotential data in the troposphere and stratosphere for 1979–2016. Contributions of eastward-traveling (E), westward-traveling (W), and stationary (S) waves are estimated. The intensification of wave activity is observed in the tropical troposphere and stratosphere and in the upper stratosphere of the entire Northern Hemisphere. The intensification of wave activity in the tropics and subtropics is noted for waves of all types (E, W, and S), while in the middle and higher latitudes it is related mainly to stationary and eastward waves. Near the subtropical tropopause, the energy of stationary waves has increased in recent decades. In addition, in the tropical and subtropical troposphere and in the subtropical lower stratosphere, the energy of the eastward-traveling waves in El Niño years may be one and a half times or twice the energy in La Niña years. The spectrally weighted zonal wave numbers for waves of all types (E, W, and S) are the largest in the upper subtropical troposphere. The spectrally weighted zonal wave number for W and S waves is correlated with the Atlantic Multidecadal Oscillation index and varies by 15% in 1979–2016 (on an interdecadal time scale). The spectrally weighted wave period is larger in the stratosphere than in the troposphere. It is maximal in the middle extratropical stratosphere. The spectrally weighted wave periods correlate with the activity of sudden stratospheric warmings. The sign of this correlation depends on the latitude, atmospheric layer, and zonal wave number.  相似文献   
5.
The first results of the paleomagnetic study of one of the key Paleoproterozoic objects of the Aldan-Stanovoy Shield (the Ulkan trough) in the Bilyakchan-Ulkan volcanoplutonic belt are presented. The volcanosedimentary rocks of the Elgetei Formation and the granites of the Ulkan Complex were studied. According to these data and their comparison with the apparent Paleoproterozoic polar wandering path in the Angara-Anabar province, the Ulkan trough was (1) located during the timing of the studied rocks at 18°–26° S and (2) subjected to rotation (relative to the Angara-Anabar block) at 70° ± 8° in the time interval of 1732–1720 Ma ago. Based on the combined interpretation of the paleomagnetic, geochronological, and geochemical data published previously, a paleogeodynamic model is proposed. According to this model, the Aldan-Stanovoy and Angara-Anabar provinces of the Siberian Craton became a single rigid block about 1720 Ma ago.  相似文献   
6.
Izvestiya, Atmospheric and Oceanic Physics - The Arctic stratosphere winter season of 2020–2021 was characterized by a weakened stratospheric polar vortex as a result of a major sudden...  相似文献   
7.
加荷与卸荷过程中的冻土强度特性   总被引:2,自引:0,他引:2  
马巍 Gury.  IE 《冰川冻土》1996,18(1):53-57
模拟冻土与构筑物相互作用的实际过程,即加荷与卸荷过程,在-5℃条件下对冻结原状粉土进行了试验,发现两种受力过程中冻土的抗剪强度不一致,卸荷时冻土的强度值要高于加荷时的,加荷时其粘聚力c=0,内摩擦角ψ=17.5°;卸荷时c=0.58,MPa,ψ=14.5°,当0.5≤σ≤4MPa时,卸荷时冻土的抗剪强度比加荷时的高1.3-3倍。纠正了长期以来认为两种受力过程中冻土的强度值是一致的看法。  相似文献   
8.
Doklady Earth Sciences - On the basis of simulations using a global climate model, the global and regional climate changes in the Holocene are estimated. According to our results, the average...  相似文献   
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10.
Based on the log-normal distribution of the grain size density function derived earlier for the entire zone of mineral disintegration, a unified granulometric taxon of perennially frozen soils is proposed which generalizes the existing soil classifications.  相似文献   
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