Home – Home – Jornals – Russian Geology and Geophysics 2008 number 5

The Oneka intrusive complex, recognized on prospecting for hydrocarbons in the western Siberian Platform, in the northern half of the Bakhta megablock (Tunguska syneclise), holds a special position among the known and new large-scale manifestations of intrusive trap magmatism. During the process, original data on the distribution of traps in the 4.2 km thick platform cover were obtained. Diverse in morphology and size, the intrusions are of the same genesis, composition, and character of intrachamber differentiation and form a

Experiment with poikilitic garnet at 3 GPa and 800

We present results of computations on the interaction of solid-phase electrum-argentite-pyrite (weight ratios 2·10^-5 / 2 · 10^-3 /1 and 2·10^-5 / 4·10^-2 / 1>) association with Cl-containing aqueous moderately acid solutions (0.5m NaCl, pH = 3.08) at 300

We suggest a model of the continental collisional framework of the southern Great Altai (Central Asia) produced by the convergence of the Tuva-Mongolia and Jonggaria terranes (microplates) during the latest Permian-Mesozoic and Cenozoic tectonic activity. The collisional structures in the region classified on the basis of their geometry and deformation style, dynamic metamorphism, and compositions of tectonites are of three main types: (i) mosaic terranes made up of large weakly deformed Paleozoic blocks separated by younger shear zones, (ii) collisional deformation systems involving post-Paleozoic structures, parallel faults oriented along collisional deformation systems, and relict lenses of Paleozoic orogenic complexes, and (iii) isolated zones of dynamic metamorphism composed mostly of collisional tectonites.

Study of morphostructures and Cenozoic deposits is important for reconstructing the history of the recent evolution of East Sayan and search for buried gold placers. Regional positive morphostructures of mountains with well-pronounced relief stages have been recognized in the Altai-Sayan area. The upper stage is referred to the Cretaceous-Paleogene; the middle one, to the Miocene-Pliocene; and the lower stage is dated at the Late Pliocene-Early Pleistocene. Negative morphostructures are recognized as a chain of intramontane basins and graben-like valleys of the Transbaikalian type. Troughs in the section bottom are filled with Cretaceous-Paleogene clayey crusts of weathering overlain by Neogene-Pleistocene deposits of complex composition. We studied the sections of Cenozoic deposits in the valleys of the Shinda and Verkhnyaya Chinzheba Rivers and made their palynological description.

High-density array MT soundings of the crust in the seismically active northern Tien Shan were performed using Phoenix MTU-5 stations in the Bishkek Geodynamic Polygon, at the junction of the Chu basin and the Kyrgyz Range. The MT transfer functions were determined to an accuracy of 1-2% (amplitude) and about 0.5-0.8 deg (phase) in most of 145 soundings. Preliminary analysis of the collected data aimed at estimating the geoelectrical dimensionality. The Bahr decomposition analysis indicated the presence of local 3D structures in the crust of the area superposed on the regional 2D structure.

The energy balance of a solid subject to fracture has been explored using heat and mass transfer equations with regard to the volumetric and superficial components. In the suggested model, brittle fracture of a cracked solid considered as a heterogeneous two-phase medium is described by an equation analogous to the Griffith's criterion for propagation of a single crack. The derived equation is used, together with estimates of relative change in specific interface area, to study the respective change of free strain energy and pressure in rocks associated with failure.