A.A. Marakushev. Geologic structure and petrological models of formation of the Earth's crust  3
N.A. Kurentsova, G.B. Udintsev. The main features of the structure and evolution of the southern part of the Scotia Sea, West Antarctic 25
Yu.D. Markov, A.V.Mozherovsky, N.G.Vashchenkova. Metalliferous sediments in the active rift zone of the East Pacific Rise (Pacific Ocean) 40
A.A. Sorokin, N.M. Kudryashov, Li Jin Yi. U-Pb geochronology of granitoids of the Oktyabrskiy complex, Mamynskiy terrane (Priamurye) 54
I.V. Kemkin, R.A. Kemkina. The structure and the age of cherty-terrigenous deposits of the Taukha terrane lower structural unit (South Sikhote-Alin) 68
V.T. Kazachenko, V.V. Kiselev. The paragenesises of manganese minerals as indicators of redox behavior of metamorphism of metalliferrous sediments 81
V.I. Isaev. Paleotemperature modeling of the sedimentary section, and oil-and-gas generation 101
D.L. Vyunov, V.A. Stepanov. Geochemical fields of the Upper Priamurye 116

Reviews
V.G. Moiseenko, V.A. Stepanov. The book "The geology of silver deposits" 125
G.L. Kirillova. Zones of oil aand gas accumulation at continental margins 127

A.A. Marakushev
Geologic structure and petrological models of formation of the Earth's crust

The continental Earth's crust developed in complex relationships with oceanic lithosphere. In the earliest days of geologic development referred to an age of 3.8 Ma, the oldest fold cores of all continents formed on the basis of the initial geosynclinal troughs of oceanic bottom. Carbonate-terrigenous sediments there were the result of destruction of uplifting structures in the zones of development of alkali magmatism (island archipelagos, etc.), similar to Farsida Rise and Olimp Volcano in the oceanic structure of the Mars's northern hemisphere.
Folding of the volcanogenic-terrigenous deposits in the initial and subsequent geosynclines, which acquired a more linear configuration, occurred under lateral thrust of oceanic lithospheres plates diverging rapidly in the periods of diastrophism away from the mid-oceanic structures (ridges). Then these plates were subducted under the newly formed fold belts; this initiated the formation of deep-seated faults, which reached the molten core of the Earth. The core was the source of rising fluid flows fixed by earthquake foci at an average depth of 60–300 km, which gave rise to the orogenic development of fold belts. The rising fluids seeping through the mantle substratum conditioned its depletion (dunitization), which formed dense roots of continents; the latter are traced geophysically down to the depths of 400–700 km. Sialic components removed by fluids from the mantle into the Earth's crust produced its general debasification accompanied with the formation of a granite-gneissic layer and an increase in the thickness of the Earth's crust protruding deep into the mantle substratum and forming roots of mountains. This disturbed isostasy and resulted in the uplifting (orogenesis) of fold belts; the uplifting was accompanied with deep erosion (cratonization) of the fold belts plus leveling of the mantle surface at a depth of about 40 km, typical of platform structures. The cratonization in the ancient shields and crystalline massifs resulted in the exposure on the platforms of metamorphic rocks, which judging by their mineral parageneses formed at 30-40 km. This reflects the mightiness of Precambrian orogenic belts, whose mountain roots were distributed deeper than the contemporary ones, which in the Andes reach 70 km in depth.
Based on the composition of the rock infilling, the depressions on the platforms are divided into sedimentary, sedimentary-volcanogenic, and volcanogenic (trappean). Marginal seas separating continents and island arcs are close to the volcanogenic type. They and trap formations trace a transition to the secondary oceanic crust, which substituted continental crust and was distributed along passive continental margins.
For all diversity, all platform depressions are genetically similar being the result of development of fluid mantle magmatism. The intrusion of ultrabasic melts with the replacement of the base of the Earth's crust caused an uplifting of mantle substratum, and the rising transmagmatic fluids accompanying ultrabasic magmatism ensured partial or complete dissolution of the granitic layer of the platform crust. This eventuated in the formation of surface depressions. The result was a characteristic reversion of surface and deep relief proper to all types of depression structures. The ore potential of depression structures, which in places becomes immense, is determined by its relation to mantle magmatism.
Marginal seas belong to structures of formation of eugeosynclinal depressions in which ultrabasite magmas intruded volcanogenic-sedimentary deep-sea deposits giving rise to an ophiolitic formation. The marginal sea structures are projected on the centers of deep-focus (300–700 km) earthquakes taking the place of the centers of medium-depth (60–300 km) earthquakes (which are correlated with relic orogenic belts of island arcs) in the course of transformation of active continental margins into passive margins. The ophiolite formations that appeared initially in the marginal sea structures constitute the base of geosynclinal deposits of troughs in the passive continental margins, which developed under conditions of weak spreading activity of the oceans. An increase in this activity of lithospheric plates conditions folding under lateral pressure of the lithospheric plates; this activity triggers new cycles of formation of fold orogenic belts of continents.