The influence of correlations in computing crustal strains from trigonometric network results

A variance-covariance analysis is made concerning the crustal strain parameters deduced from triangulation results. The coordinate difference method is treated, the algorithm of the analysis being valid for either free or constrained network adjustments. The importance of the correlations entering into the calculation of the standard deviations of strains is emphasized, showing how even poor geodetic results can be sometimes useful in crustal strain analyses.     

First results of fair-weather atmospheric electricity measurements in Northeast India

During the month of March 2006, a short campaign was conducted to measure fair-weather atmospheric electricity parameters in Tripura, Northeast India (23.50°N, 91.25°E). The campaign was the first of its kind in this region of the globe. The main objective of the campaign was to characterize the diurnal variation of three parameters namely vertical potential gradient (E), vertical air-earth current density (J _z ) and atmospheric electrical conductivity (σ) in fair-weather conditions. The diurnal variation of E and J _z over sixteen fair-weather days shows two distinct maxima around 14UT and 20UT and a minimum around 03UT. The average vertical potential gradient is found to be 108V·m⁻¹ and air-earth current density 1.85 pA·m⁻². The average bipolar atmospheric electrical conductivity at the ground level is found to be 19.6 fS·m⁻¹. An excellent positive correlation between E and J _z is found, with a correlation coefficient of 0.96. A comparative study with Carnegie universal variation shows 70% correlation with observed variation of vertical potential gradient during the period of the campaign. The results are discussed in view of difficulty as well as possibility of getting global signatures in atmospheric electricity measurements made from tropical land stations.     

First results of GPS measurements on the Ulaanbaatar geodynamic testing area

First results of the analysis of GPS measurement data obtained from 18 sites of two local networks in the vicinity of Ulaanbaatar (Mongolia) for the period 2010–2015 have been presented. Horizontal velocity vectors are consistent with each other in the ITRF2014 system and with the velocities of the IGS permanent station ULAB. The sites move in the E–SE direction at a rate of 25–30 mm/yr, with the displacement azimuth averaging 105°. With respect to Eurasia, the vectors for most of the sites are slighly turned to the south, but they are still of SE orientation with the azimuth range of 130°–150° and magnitude values of 2–4 mm/yr. Relative horizontal velocities tend to decrease towards southeast that determines a zonal distribution of different type of relative strain patterns. The western part of the Ulaanbaatar network is characterized by the W–E oriented extension with the elongation rate ε₁ = 12–16 × 10^–8 yr^–1. The shortening NW–SE trending strain with calculated value ε₂ = 22.4 × 10^–8 yr^–1 characterizes the network’s eastern part. The highest values of the maximum shear strains (ε_max = 10–14 × 10^–8 yr^–1) form an extended area in the center of the testing ground, which is elongated in the northeastern direction, conformably with the strike of the major geologic structures. The strain distribution pattern of the Emeelt network located within the eponymous seismogenic structures is characterized by the crustal elongation (5 × 10^–6 yr^–1) trending SE–NW and less pronounced shortening in the SW–SE directions.The axial part of the fault crossing the network in the NW direction exhibits maximum deformations.     

SMART-1 after lunar capture: First results and perspectives

SMART-1 is a technology demonstration mission for deep space solar electrical propulsion and technologies for the future. SMART-1 is Europe’s first lunar mission and will contribute to developing an international program of lunar exploration. The spacecraft was launched on 27th September 2003, as an auxiliary passenger to GTO on Ariane 5, to reach the Moon after a 15-month cruise, with lunar capture on 15th November 2004, just a week before the International Lunar Conference in Udaipur. SMART-1 carries seven experiments, including three remote sensing instruments used during the mission’s nominal six months and one year extension in lunar science orbit. These instruments will contribute to key planetary scientific questions, related to theories of lunar origin and evolution, the global and local crustal composition, the search for cold traps at the lunar poles and the mapping of potential lunar resources     

Long-term seismic noise investigations on Shikotan Island: First results

In 2003–2004, long-term seismic noise observations were launched on Shikotan Island (Lesser Kuril Range) based on the “Shikotan” dormant regional seismic station. The geological and geophysical data on the registration area are reported. Information about the equipment and its technical specifications is given. The precursors to the strongest local earthquakesthat occurred in the Shikotan Island region in January 2005–March 2007 are identified.     

The accuracy with which coordinates of radio telescopes can be estimated using VLBI observations

Methods for external estimation of the accuracy of geodetic parameters (the coordinates of radio telescopes) based on VLBI observations are discussed. Time series of the distances between radio telescopes (baselines) provide the observational material for the analysis. It is shown that the generally accepted model for estimating the accuracy of geodetic results is based on unjustified assumptions, and does not adequately describe the results of geodetic observations. A more flexible parametrical model is proposed, which takes into account the non-uniformity in the accuracies with which geodetic parameters for different stations can be estimated, and more adequately describes the observational data. The evolution of the Svetloe-Badary and Zelenchuk-Badary baselines in 2007–2012 is analyzed in detail. The Badary VLBI station located near Irkutsk is moving away from the other two stations, located in the European part of Russia, at a rate of 3–4 mm/year.     

Deep surveys and the nonthermal noise of radio telescopes

The paper presents an analysis of catalogs of discrete radio sources and the results of deep surveys carried out with angular resolutions to 1.5″ and limiting flux densities to 9 μJy at frequencies from 80 MHz to 8.5 GHz using large radio telescopes around the world. We consider the influence on the sensitivity of a radio telescope of the nonthermal noise associated with variations in the total flux due to fluctuations in the number of unresolved sources with fluxes lower than the observed value that fall in the main lobe of the antenna beam when the direction in which the receiver is pointed is changed (the first component), and also due to sources with fluxes higher than the observed value that arrive in the scattering region of the telescope (the second component). With growth in the sensitivity and resolution of a telescope, the second component of this nonthermal noise determines to an appreciable extent the limiting capability of the telescope for carrying out deep surveys. We estimate the number of antenna beams per source that are required to reach a specified sensitivity in deep surveys. The results of our calculations are compared with data derived from catalogs and numerous surveys.     

First results from imaging riometer installed at Indian Antarctic station Maitri

Cosmic noise absorption (CNA) measurred by imaging riometer, is an excellent tool to passively study the high latitude D-region ionospheric conditions and dynamics. An imaging riometer has been installed at Indian Antarctic station Maitri (geographic 70.75°S, 11.75°E; corrected geomagnetic 63.11°S, 53.59°E) in February 2010. This is the first paper using the imaging riometer data from Maitri. The present paper introduces the details of this facility, including its instrumentation, related CNA theory and its applications. Sidereal shift of around 2 hours in the diurnal pattern validates the data obtained from the newly installed instrument. Moreover, the strength of cosmic noise signal on quiet days also varies with months. This is apparently due to solar ionization of D-region ionosphere causing enhanced electron density where collision frequency is already high. The main objective of installing the imaging riometer at Maitri is to study magneotspheric–ionospheric coupling during substorm processes. In the current study, we present two typical examples of disturbed time CNA associated with storm-time and non-storm time substorm. Results reveal that CNA is more pronounced during storm-time substorm as compared to non-storm time substorm. The level of CNA strongly depends upon the strengthening of convectional electric field and the duration of southward turning of interplanetary magnetic field before the substorm onset.     

Crystallographic orientations of high-angle grain boundaries in dynamically recrystallized quartz: First results

The crystallography and geometry of high-angle grain boundaries from dynamically recrystallized quartz have been studied. On the basis of combined electron backscatter diffraction and universal stage measurements, the complete crystallographic orientation of the grain boundaries could be calculated. The u-stage rotation of the grain boundaries to a vertical position reveals that they are never curved but always consist of straight segments. Our results show that these segments preferentially occupy rhombohedral, trapezohedral and bipyramidal orientations, i.e., orientations in a  25–50° girdle to the c-axis. A specific, albeit low, number of segments with special crystallographic orientation, with respect to a neighbouring quartz grain, often shows another special orientation with respect to the other neighbouring grain. Preferred combinations of grain boundary orientations related to both neighbouring grains are (i) low-index rhombohedral and high index trapezohedral, (ii) low-index bipyramidal and low-index trapezohedral or high-index rhombohedral, and (iii) low-index trapezohedral and low or high index trapezohedral. In certain cases, such as at triple junctions, the boundaries occupy specific trapezohedral orientations with a constant angle to the c-axis. This argues for energy isotropy of trapezohedral planes with the same angle to the quartz c-axis. In general, good match coincidence site lattice (CSL) orientations are not preferentially occupied so that most of the studied grain boundaries represent general boundaries. The formation of straight segments in special crystallographic orientations indicates the crystallographic control and implies an energy reduction of certain general boundaries.     

U-Th-He dating of native gold: First results,problems, and outlooks

In this paper, we consider the application of the U-Th-He method of isotope geochronology for native gold dating. It was shown that inclusions of uranium- and thorium-bearing minerals, including rare earth element phosphates, are one of the main form of uranium and thorium occurrence and, consequently, the main source of radiogenic helium in native gold. Since these inclusions are submicrometer-sized, the radiogenic helium formed in them is not accumulated but implanted in the structure of native gold, which suggests its good preservation over billions of years. This suggestion was experimentally supported by the investigation of the kinetics of radiogenic helium release from native gold. The first results of the U-Th-He dating of native gold from the Pedrolampi (central Karelia) and Witwatersrand (South Africa) deposits are in adequate agreement with available independent geochronological data. This allows us to consider native gold as a U-Th-He mineral geochronometer for the direct dating of ore-forming processes.     

Pore to pore validation of pore network modelling against micromodel experiment results

Pore network modelling (PNM) has been widely used to study the multiphase flow and transport in porous media. Although a number of recent papers discussed the PNM validation on core-scale parameters such as permeability, relative permeability and capillary pressure; quantitative predictive potential of PNM on pore by pore basis has rarely been studied. The aim of this paper is to present a direct comparison between PNM simulations and corresponding micro-model experiments at the same scale and the same geometry. A number of well-defined and constrained two-phase flow in porous medium experimental scenarios were utilized to validate the physics solving part in PNM (filling rules, capillary and viscous pressure). This work validates that a dynamic pore network flow solver can predict two-phase flow displacements for these experiments for drainage situations at both pore and plug scales. A glass-etched micro-model is used to quantify the accuracy of a dynamic PNM solver on pore and core levels. Two-phase drainage micro fluidic experiments at different flow conditions are performed on micro-models. PNM simulations are performed on the same pattern and flow conditions as used in micro-model experiments. The two-phase distribution extracted from experiment images is registered onto rsults of PNM simulations for direct pore to pore comparison. Pore-scale matching level is found at around 75 % for all three test cases. The matching level of core-scale parameters such as S _{w c} and oil-phase permeability varies from case to case; the relative error to micro-model experiment measurements varies from 15 to 60 %. Possible reasons leading to discrepancies on core-scale parameters are discussed: missing considerations during validation of the combination of uncertainty in both simulator input parameters and experiments are seen as the principal factors.     

An introduction to the European Geotraverse Project: First results and present plans

The European Geotraverse (EGT) is an international, multidisciplinary project focused on a north-south orientated lithospheric profile, 4000 km long and of varying width, extending from northernmost Scandinavia to North Africa. This profile consists of three interlinking Segments (Northern, Central, and Southern) comprising a continuous succession of tectonic provinces ranging from the oldest Precambrian areas of the Baltic Shield to the currently active area of the Western Mediterranean. The broad aim of the EGT Project is to obtain a better three-dimensional picture of the structure, state, and composition of the continental lithosphere to use as a basis for an understanding of its evolution and dynamics. All of the 12 major projects that constitute the EGT “Joint Programme” have now been initiated, and several of these projects are nearing completion.Along the Northern Segment, data from “The Fennoscandian Long-Range Project” (FENNOLORA), a 2000 km long seismic profile across the Precambrian Baltic Shield, show that except beneath southern Sweden, the Shield is characterized by a high-velocity, 40–50 km thick crust—including a 5–10 km thick crust-mantle transition zone. An alternating series of 4–6 high- and low-velocity zones is present in the subcrustal lithosphere, the base of which increases in depth from ca. 110 km to ca. 230 km from south to north beneath the Shield. The top of the mantle transition zone lies at a depth of about 450 km. The second major project along this Segment, the EUGENO-S (European Geotraverse Northern Segment—Southern Part) project, is a multidisciplinary study of the Fennoscandian Border Zone, and was largely completed in 1984 with the realization of a large-scale seismic experiment. Preliminary interpretation of the excellent data obtained indicate the presence of strong lateral variations in internal crustal structure beneath the Danish Basin. Field work for a third major project, a multidisciplinary transect of the Archaean and Early Proterozoic terrains in the northernmost part of the Shield (the “Polar Profile”), was carried out in 1985.A series of deep seismic reflection lines has so far been realized in the area of the Central Segment in the context of German national programmes. First interpretations of the seismic data from a 260 km long profile across the two main intra-Variscan (Hercynian) lineaments have shown the presence of numerous horizons making up a highly reflective zone in the lowermost 10 km of the crustal section studied, and distinct changes in reflectivity between the main Variscan tectonic zones. In 1986, the entire Segment will be investigated in detail in an ambitious international programme of integrated geological and geophysical studies.A series of seismic experiments (termed EGT-S) have been carried out across the Southern Segment (in 1982, 1983, and 1985). Interpretation of data from the 1982 and 1983 experiments have led to several interesting results, including:

• 1.(1) the suggestion that two “crust-mantle”-like interfaces exist beneath the Po Basin (at depths of about 35 and 50 km) and adjacent tectonic units, these interfaces marking a deep contact zone between the Adriatic and European plates,
• 2.(2) in the area between Genoa and Corsica, the Ligurian Sea is underlain by a greatly thinned, distinctly layered section of continental crust, and
• 3.(3) Corsica and Sardinia are underlain by bowl-shaped, “typically” Variscan continental crusts.

The 1985 phase of seismic surveys focused on crustal structure beneath Tunisia and the adjacent seas.In addition, two off-traverse projects are being realized. First, a wide-aperture network of autonomously recording seismic stations (“NARS”), installed along the line Gothenburg-Málaga between 1982 and 1984, is already yielding high-quality data on the upper 600–700 km of the mantle. Second, an investigation of lithospheric seismic anisotropy in the area of the Iberian Peninsula is being organized for 1987–1988.Finally, of great importance are the systematic compilation of existing data and, where needed in critical regions, collection of new geophysical and geological data presently being carried out for the entire area encompassed by the EGT. It is expected that these compilations will be completed by 1987, at about the same time that full results from the main large-scale seismic experiments become available, enabling the construction of an integrated lithospheric cross-section along the EGT, requiring a final phase of intensive multidisciplinary collaboration.     

HYC (McArthur River) SEDEX deposit, Australia: First paleomagnetic results

Analysis of pyrrhotite-borne paleomagnetic data from four sites on each limb of a syncline through the supergiant HYC (McArthur River) SEDEX Zn–Pb deposit in Australia indicates that the mineralization is entirely postfolding, formed within 15 Myr after deposition at 1640 Ma of the host Barney Creek Formation, and thus is either late syndiagenetic or epigenetic in origin.     

The First All-Russia Lithological Conference

Lithology and Mineral Resources -     

我国产出的曼纳德石(Mannardite)Ba(Ti6V2)O(16)

一九八○年,四川省地矿局中心实验室在研究四川甘孜白玉麻邛呷村多金属矿床的物质成分及银的赋存状态时,发现了一个新矿物,后命名为甘孜矿。经过较长时间反复研究,直到最近才决定报国际矿物协会(IMA)。但我国新矿物及矿物命名委员会告知,加拿大J.D.Scott等在一九八三年就以曼纳德石     

我国首次发现的锌—砷黝铜矿

锌-砷黝铜矿产于内蒙的某一铅锌矽卡岩矿床中,呈它形粒状集合体,粒径0.2-0.5mm,铅灰色,硬度HvHN=339-388kg/mm2。反射色呈灰蓝色微带绿色。均质性。其成分经电子探针分析(平均值)为:S 25.94,As 10.70,Cu 39.67,Zn 7.36,Sb 9.81,Bi 5.81,Ag 0.18,Fe 0.37(%),化学式为:(Cu10.02Age03)10.05(Zn1.81Fe0.11)1.82(As2.29Sb1.29Bi0.45)4.03S18。X射线分析:晶胞参数a=10.322,粉末衍射强线是2.98,1.82,1.56。