A. V. Mel’nikov

Lyapunov exponents in the Hénon-Heiles problem

The maximal Lyapunov characteristic exponent of chaotic motion was calculated as a function of the system energy by numerical integration of the Hénon-Heiles problem. Contrary to the conclusions of Benettin et al.

Age of the Berezitovoe Gold-Base Metal Deposit in the Western Selenga-Stanovoi Superterrane and Its Relation to Magmatism

The Selenga‐Stanovoi Superterrane [1] in the southeastern margin of the North Asian Craton is one of the key structures of eastern Asia. Its geological structure is mainly composed of conditionally defined Early and Later Precambrian rock complexes, as well as numerous Paleozoic‐Mesozoic intrusive and volcanoplutonic associations. The intricate and multistage evolution of tectonic structures was characterized by the functioning of magmatic and ore-forming systems of various ages and types related to different geodynamic settings, resulting in the formation of no less complicated metallogenic specialization of the region. Numerous data obtained recently make it possible to specify the ages of igneous and metamorphic rock complexes and, correspondingly, to revise the existing concepts of the regional geological structure. However, isotopic‐geochronological information on most ore objects remains insufficient. Therefore, it is rather difficult to correlate tectonic, magmatic, and ore-forming processes. According to metallogenic models, the majority of ore objects are Mesozoic structures [2 and others]. However, these models are based largely on the macroscopic association of mineralization with different magmatic processes. Systematic geochronological studies of ore deposits with application of advanced methods were introduced only during the past few years [3‐5 and others]. In this communication, we

The Lyapunov exponents in the dynamics of triple star systems

The dynamics of weakly heirarchical triple stars with equal masses are considered. Full spectra of the Lyapunov exponents are found via numerical integration of the orbits, for various initial configurations of the systemin the planar problem and with initial conditions in the vicinity of the 2 : 1 resonance (i.e., with the initial ratios of the periods of the outer and inner binaries being close to 2 : 1). Dependences between the Lyapunov time and the disruption time of the systemare constructed for initial conditions near and far from resonance. The character of these relationships is different near and far from resonance, corresponding to two kinds of Hamiltonian intermittency. The trajectories “stick” to the regular component in phase space near resonance, while this effect is not dominant far from resonance. Analysis of the distributions of the disruption times of the triple systems for initial conditions near and far from resonance confirm these conclusions.

Changes in spontaneous brain bioelectrical activity during transcranial electrical and electromagnetic stimulation

The systems responses of the brain to therapeutic transcranial electrical and electromagnetic stimulation were studied and the neurophysiological criteria for assessing the efficacy of this treatment were identified using comparative clinical and experimental studies with analysis of spontaneous bioelectrical activity, along with assessment of behavioral and clinical measures. Study groups consisted of six patients with chronic post-traumatic unconscious states during courses of transcranial electrical stimulation and 17 intact Wistar rats subjected to transcranial electromagnetic stimulation. A relationship was found between the effects of transcranial stimulation and the initial level of intercenter interactions of brain bioelectrical activity assessed in terms of coherence. Hypersynchronization of biopotentials, identified as a major element in the reactivity to this type of stimulation, may be of the greatest value in the recovery of patients with cerebral pathology in cases with initially reduced levels of intercenter interactions in the absence of pathologically increased functional connections in the brain.

Unusual rotation modes of minor planetary satellites

An analysis of the character of the possible dynamics of all hitherto known planetary satellites shows two satellites—Amalthea (J5) and Prometheus (S16)—to have the most unusual structure of the phase space of possible rotational motion. These are the only satellites whose phase space of planar rotation may host synchronous resonances of three different kinds: the α resonance, the β resonance, and a mode corresponding to the period doubling bifurcation of the α resonance. We analyze the stability of these states against the tilt of the rotational axis.

Stability of the multiple star system ι UMa (ADS 7114)

The physical and orbital parameters of the quadruple star system ι UMa (HD 76644 = ADS 7114) were determined earlier, when it was concluded based on modeling the system’s dynamics and applying theoretical stability criteria that the system was probably unstable. Here the stability of the ι UMa system is studied by calculating the Lyapunov characteristic exponents for representative sets of parameters and initial conditions. The conclusions on the system’s stability (or instability) based on various stability criteria and the calculated Lyapunov exponents are compared. The instability of the system as a whole is confirmed rigorously based on massive computations of the Lyapunov exponents. This system appears to be the only known multiple system whose instability has been rigorously established. The Lyapunov time-disruption time statistical relations are constructed, which show that the Hamiltonian intermittency of the second kind dominates. Typical disruption times are shorter than 1000 years, and the Lyapunov times are shorter than 100 years.

Platinum potential of the Stanovaya metallogenic zone (Far East, Russia)

447 The Stanovaya metallogenic zone occurs along the southeastern margin of the Northern Asian Craton with a length of 1300 km and a width of ~250–300 km. The metallogenic zone is located in the eastern part of the Stanovoi megablock limited by the Stanovoi deep fault from the north and by the Mongol–Okhotsk deep fault from the south. A megablock surrounds the Aldan protomassif, represented by a folded–block or granite–greenstone area that underwent Mesozoic tectonomagmatic activization. The structure of the territory includes a number of blocks composed of Early Archean (Zverevsko–Chogarskii and Zeiskii Complexes) and Late Archean (Stanovoi and Gily uiskii Complexes) metamorphic rocks. Intercratonic troughs are filled by formations of the Early Protero zoic Dzheltulakskii Complex represented by phyllite like, biotite, and two mica schists, quartzites, meta conglomerates, and metaeffusive rocks [1].

New types of gold-platinum metal mineralization in the upper Amur region

Kyanite‐sillimanite metasomatites. The garnetbearing kyanite and kyanite‐sillimanite metasomatites (Talgin Formation) of the Dzhalta sector (Dzhalta‐ Ul’degit river basin) incorporate thick zones of silicification, sericitization, chloritization, and nest-stringer sulfidization (pyrrhotite, chalcopyrite, pyrite, and pentlandite). The ICP-AAA analysis of 30 lump and chip samples (IRGIREDMET Laboratory, Irkutsk) showed that the sulfidized kyanite‐sillimanite metasomatites contain Au (0.05‐1.5 g/t). Contents of noble metals in samples with quartz veins are as follows (g/t): Au up to 1‐3, Ag 0.07‐3.5, Pt 0.09‐0.79, and Pd 0.04‐0.14 [1]. Mineralogical analysis of pan samples of the chloritoid‐kyanite schists made it possible to divide the heavy fraction into the (1) magnetic, (2) electromagnetic, and (3) nonmagnetic fractions. The magnetic fraction includes iron globules (0.1‐1.0 mm in size) and magnetite. The electromagnetic fraction can be divided into three types. Type I is composed of ilmenite (up to 75%) and chloritoid. Type II is composed of chloritoid (up to 85%) and kyanite. Type III is composed of chloritoid and kyanite. The nonmagnetic fraction includes kyanite (up to 85%). The inversion voltamperometric analysis (analytical center of the ZolotoPlatina Territorial Production Association, Tomsk) made it possible to determine concentrations of noble metals in the samples (Table 1). Based on the ICP-AAA analysis, contents of noble metals in kyanite fractions (7 samples) are as follows (g/t): Pt 0.24‐1.45, Pd 0.04‐0.1, Au 0.22‐1.14, and Ag 0.3‐2.5. The microscopic examination by V.I. Gvozdev (Far East Geological Institute, Vladivostok) revealed that kyanite samples contain Au and Pt particles (0.04‐0.3 mm in size) and abundant microinclusions of monazite, zircon, magnetite, and sulfides (pyrite, pyrrhotite, and chalcopyrite). Thus, platinum mineralization discovered in metamorphosed rocks of the Talgin Formation indicates that “discordant” bodies of the upper Amur region are enriched in Pt. Ferruginous quartzites. In basins of the Goratsiev and Radostnyi creeks (Dzhalta River system), graphite, graphite‐biotite, and biotite gneisses of the Early Archean Kamrai Formation incorporate thick magnetite‐amphibole quartzite units (up to 30‐40 m) with rare sulfide dissemination (pyrrhotite, chalcopyrite, and pyrite). Based on magnetic and geological survey data,

Tokur gold ore–placer cluster in Amur Province: Geological–structural features and perspective of its development

The geological–structural features and gold-potential perspective of the Tokur ore–placer cluster in the Amur Province have been studied. This ore–placer cluster is a syncline composed of Paleozoic blackshale sequence, which is cut through by Late Paleozoic and Late Mesozoic intrusions. A granitoid massif is suggested at the depth on the basis of geophysical data. The cluster is distinguished by high productivity. Approximately 37 t gold from ore deposits, primarily from the Tokur deposit, and 60 t from placers have been mined out. The Tokur deposit is compared with the Natalka and Degdekan deposits from the Yana–Kolyma Province. Perspectives of the cluster area for large gold–quartz deposits and technogenic gold placers have been estimated.

Prospects for gold mineralization in the Arkhara ore-placer cluster of the Amur region (Russia)

208 The Arkhara ore–placer cluster is located on the southern flank of the Amur gold bearing province and represents an element of the Turan metallogenic zone [3]. The cluster comprises small gold placers and ore occurrences, with some of them being overlain by pla teau basalts. To increase the gold bearing potential of Amur oblast, which became second in Russia by gold production in 2011–2012 [2], we assessed for the first time the prospects of the poorly investigated Arkhara cluster with respect to ore and placer gold. The cluster hosts mainly Paleozoic granitoid mas sifs and subordinate Precambrian metamorphic rocks and Late Paleozoic volcanics. Along the periphery of the cluster, all these rock are overlain by Neogene pla teau basalts and Neogene–Early Quaternary uncon solidated sediments. As a whole, the cluster corre sponds to a dome shaped intrusion fringed by Upper Cenozoic–Lower Quaternary unconsolidated sedi ments and plateau basalts (Fig. 1). The radial sublati tudiinal and submeridional fractures divide the cluster into several sectorial and segmental blocks. The gold ore occurrences are recorded in the southern (Ivanovskoe, Igorevskoe, Yuzhnoe) and cen tral (Sobornoe) parts of the cluster. The Sobornoe ore occurrence is located in the Birya River basin on its right side. This area is composed of granitoids of the Tyrma–Bureya Complex and acid volcanics of the Upper Permian–Lower Triassic Taloe Sequence with the latter rocks forming two tectonic blocks. One of them 7 × 3 km in size is bordered by lat itudinal faults. The second block extends in the sub meridional direction. Volcanics are pyritized, silici fied, and chloritized being characterized by a quartz ite like appearance. The content of fine crystalline pyrite amounts to 3–7%. Their hydrothermal alter ations are controlled by tectonic fractures. In the pyri tized variety of volcanics, the content of Au and Ag varies from 0.002–0.5 to 10.2 (in one sample) and 0.1–3.0 to 17.3 g/t (in one sample), respectively, and that of Pb amounts to 0.002–0.2%. In beresitized granites with disseminated sulfides, the respective Au and Ag concentrations are as high as 0.05–5.3 and 0.1–3.5 g/t.