Home – Home – Jornals – Russian Geology and Geophysics 2003 number 3

The Vendian-Early Cambrian, Middle Cambrian, and Early Ordovician volcanosedimentary deposits of the Martaiga block of the Kuznetsk-Alatau paleoisland arc (55.5

The paper presents results of integrated detailed surveys by a Simrad EM-12 S120 multibeam echosounder, a MAK-1M deep-towed side-scan sonar, dragging, and gas measurements in surface water on the Caucasian continental slope in the Russian Black Sea. The combined use of these methods proved its efficiency in hydrocarbon exploration in folded and faulted regions of steep continental slopes.

We present results of study of contact rocks from the Nyurundukan ultramafic-mafic massif in the northern Baikal region. The host metabasites metamorphosed in the conditions of amphibolite facies are shown to have undergone high-temperature (T ~880

We have obtained more than 30 radiothermoluminescence (RTL) dates for loose sediments from the Tunka Rift, lithologically divided into sandy, boulder-pebble, terrace, slope, and cover formations. The sandy fluvial sediments are dated to 76.00-31.50 Ka, and the eolian sediments formed from them, to 16.12-8.31 Ka. We have first determined the age of the Mondy moraine in the west of the Tunka Rift - 70.00-72.00 Ka. The age of the ancient alluvium buried under it varies from 101.5 to 132 Ka. The oldest sediments of this complex (153 Ka?) occur in the base of the ancient alluvium of the Ikhe-Ukhgun' River, at its intersection with the Nilov spur. Radiocarbon and RTL dates obtained for the base of the lower terraces of the Irkut River made up of Holocene deposits yield an age of 53.40 and 40.06 Ka, respectively. The lower part of the slope sediments is dated to 22.00 Ka, and the pebbles overlapping the bases and slopes of young volcanoes in the Tunka depression, to 39.00 and 70.00 Ka, respectively.

The roots of disagreement on the energetics of exogenous processes have been analyzed in the context of modern views on water-rock interaction. Results of thermodynamic analysis of weathering reactions are reported. It is shown that the formation of supergene clays involves two different geological processes: hydrolysis of aluminosilicates and binding of large amounts of water. Relative to the free water, the bound water has a higher free energy of formation. This difference considerably changes the energetics of hydrolysis reactions, which actually are all endothermic. The conclusion is made that physically bound water and, therefore, clays bear large stocks of accumulated solar energy. This fact proves that oriented inner evolution and self-organization took place in inorganic matter like those known in biogenic systems, with a genetic relationship existing between them.

Seventeen Middle Paleozoic haloes of kimberlite minerals have been distinguished in Middle Devonian, Early Carboniferous, and younger terrigenous collectors in the south of the Siberian Platform. The paleogeographic settings in which they formed rule out supply of material from the already discovered bodies and suggest erosion of numerous local coeval primary sources. Comparison of the haloes with the model for kimberlite field manifestation in terrigenous collectors, elaborated on the basis of known kimberlite fields in Western Yakutia, evidences that they are cut off from primary sources. We predict the existence of Middle Paleozoic kimberlites buried under Permian-Triassic deposits in southern Siberia. These kimberlites, apparently, differ from the known West Yakutian pipes in manifestation of earlier phases of intrusion and in essentially pyrope composition of indicator minerals.

The applicability of near-field TEM-TDEM soundings to hydrocarbon exploration in the geological conditions of West Siberia is analyzed on the basis of standard and new techniques of data acquisition and processing. The new approach including polarization effects produced by the presence of hydrocarbons is much more efficient than the standard techniques restricted to resistivity variations. The new method was tested in a number of known and new oil and gas fields in the Middle Ob' region.

Numerical simulation of the global electric field generated by thunderstorms in a static model shows that the polarity and value of Earth charge depend on latitudinal variations of atmospheric conductivity. The closest to nature atmospheric conductivity profiles correspond to a positive charge. The total Earth charge is calculated as a function of latitudinal variations of atmospheric conductivity including the effects of the Earth's orography and conductivity anisotropy in the ionosphere.

An approach to estimation of physical properties of reservoirs based on lithofacies conditions of their formation has been discussed. The Jurassic sediments of the East Surgut oil deposit are distinguished by diversity of facies varieties and thus are appropriate for illustrating the approach. It is reasonable to calculate the reservoir porosity using separate facies for each stratum. A facies-based technique is proposed to dismember the strata with the use of author's cross plots for estimating the porosity of Jurassic deposits of the Surgut arch.