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We studied the neutron quantum states in the potential well formed by the Earth's gravitational field and a horizontal mirror. The estimated characteristic sizes of the neutron wave functions in […]

A new compilation of deep seismic reflection data, in combination with the results of recent geological and isotopic investigations, provides the basis for significantly refined structural and evolutionary models of the Middle Urals. Many of the major structural boundaries observed at the surface (e.g. Main Uralian Thrust, Main Uralian Normal Fault, Serov-Mauk Fault, Prianitchnikova Shear Zone) can be followed on the seismic reflection data to depths of 8-15 km. Only a few features can be traced through the horizontal to shallow dipping zones of middle-crustal reflectivity that extend beneath much of the Middle Urals. Exceptions might be the Deevo Thrust and a newly discovered deep band of moderately dipping reflections beneath the West Siberian Basin that may represent the remnants of an ancient subduction zone. The reflectivity of the lower crust and Moho are similar beneath the hinterland of the Urals and below the western part of the West Siberian Basin, suggesting that in both places they have the same extensional origin. Accretion of various exotic terranes to the eastern margin of Baltica during Late Palaeozoic time involved considerable shortening of the continental margin. The accreted terranes (e.g. Tagil, Petrokamensk and Alapaevsk Arc Complexes) consist mostly of island-arc material formed during Mid- and Late Palaeozoic time. Closely associated with the island arcs are several high-grade metamorphic complexes (e.g. Salda and Murzinka--Adui Complexes) that were exhumed during and after Late Palaeozoic convergence. Towards the end of the orogeny, several north-south-trending strike-slip faults (e.g. Sisert Fault) were active. After the orogeny, major periods of tectonism and magmatism in the Middle Urals resulted in the extrusion of the Siberian trap basalts, crustal stretching and/or underplating, and the formation of the West Siberian Basin, the planet's largest intracontinental sedimentary basin. Finally, a period of renewed thrust faulting, often reactivating older faults, led to the inversion of the Mesozoic basins. Keywords: Uralide Orogen, West Siberian Basin, Palaeozoic, Mesozoic, seismic profiling.

A series of experiments has been performed to measure prompt neutron angular and energy distributions from thermal neutron-induced fission of 235,233U in correlation with the fission fragments. These distributions have been analyzed with the assumption of neutron isotropic emission from accelerated fission fragments. The performed analysis demonstrates that all obtained results can be described within 5% accuracy using this assumption. This discrepancy is approximately constant and doesn’t depend on fragment mass and the total kinetic energy (TKE). Some minor peculiarities of angular distribution may be interpreted as a result of anisotropy of the fission neutron angular distribution in the fragment center-of-mass system.

Abstract: Metamorphism in the northern sector of the Main Uralian Fault (MUF) area, northern Urals, is considered by the example of the Salatim glaucophane-schist and Belokamenka kyanite-staurolite complexes. New isotope-geochronological dates for metamorphic rocks of the MUF area are presented. The obtained data evidence the existence of two metamorphic events, of Early and Late Devonian ages, which apparently correspond to the wedging-up of subduction paleozones. [Copyright &y& Elsevier]