POSITION OF ARSENIC MINERALS IN THE METALLOGENIC SERIES.

The fact that there is certain definite order in the distribution of metallic ores around a central magma has now been generally recognized by economic geologists and its effects on the geographic distribution as well as     

Active wrench faults of Iran,Afghanistan and Pakistan

The fault pattern of Iran, Afghanistan, and Pakistan has been mapped from air-photo-mosaics. The Herat, Chaman, Shahrud, Doruneh, and Zagros are the five major active faults and are wrench in character. With the exception of the Chaman fault, which lies to the east, the faults or their extensions spiral out from a centre in the Dasht Lut Depression of eastern Iran, the dextral faults spiralling out clockwise and the sinistral faults anticlockwise. The spiral fault pattern is consistent with that expected from a central force, and from the relation between the sense of horizontal displacement and the direction of outspiralling it is inferred that the crustal blocks west of the Chaman fault are moving in towards the Lut Centre. Similar spiral fault patterns can be recognized at many places in the world, and their centres are probably critical for explaining present day tectonics.-- , , , . — , , , — . , , , .

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Zusammenfassung Auf einer beigegebenen Karte wird der Verlauf von aktiven und von vermutlichen Hauptverwerfungen in Afghanistan, Pakistan und im Iran gezeigt, wie er anhand von Luftbild-Mosaikkarten und Luftaufnahmen bestimmt wurde. Die fünf wichtigsten aktiven Dislokationen sind die Herat-, Chaman-, Sharud-, Doruneh- und die Zagros-Verwerfung.Die deutlich sichtbare Herat-Verwerfung erstreckt sich in ENE-Richtung über 800 km durch den Nordteil Afghanistans zur chinesischen Grenze. Ihre Verschiebung erfolgte rechtsläufig, so daß die nördliche Scholle relativ zur südlichen nach E versetzt wurde.Die etwa 700 km lange nach SSW weisende Chaman-Verwerfung zieht sich in zwei schwach gegensinnig geschwungenen Bögen von der Herat-Verwerfung wenig N Kabul die afghanisch-pakistanische Grenze entlang, um in zahlreiche Zweigverwerfungen aufzuspalten, die in Westpakistan nach W umbiegen. Die Verschiebung erfolgte linksläufig und ist gut sichtbar.Die Sharud-Verwerfung im Iran erstreckt sich nach ENE durch die Achse des Elburs-Gebirges und biegt dann nach SE parallel zur russischen Grenze ab. Die Verwerfung ändert häufig ihre Richtung und ist nur schwer zu verfolgen. Sie hat eine sichere Länge von 800 km und ist linksläufig.Die gut sichtbare Doruneh-Verwerfung verläuft in Kurven 250 km südlich der Sharud-Verwerfung derselben parallel. Nach E spaltet sie sich auf, nach W vereinigt sie sich vermutlich mit der Sharud-Verwerfung. Sie ist 600 km lang und linksläufig.Die Zagros-Verwerfung tritt auf Luftaufnahmen am wenigsten hervor, auf geologischen Karten ist sie jedoch eine Hauptverwerfung. Sie erstreckt sich vom Schnittpunkt der drei Grenzen des Iran, Irak und der Türkei 950 km nach SE bis fast zur pakistanischen Grenze, wo sie wahrscheinlich anfangs nach NW, später nach N umbiegt. Die Verwerfung ist wahrscheinlich rechtsläufig.Die fünf Hauptverwerfungen, zusammen mit vier kleineren Verwerfungen, deren horizontaler Verschiebungssinn bekannt ist, bilden ein relativ einfaches Strukturmuster.Mit Ausnahme der Chaman-Verwerfung, die im E liegt, verlaufen die Verwerfungen oder ihre Ausläufer ausgehend von einem in der Dasht Lut-Senke gelegenen Zentrum in Gestalt einzelner Spiralen sternförmig nach allen Seiten; die in ihrem Verschiebungssinn rechtsläufigen im Uhrzeigersinn gebogen, die linksläufigen in Gegenrichtung gekrümmt. Die übrigen geologischen und morphologischen Hauptlinien zeigen ebenfalls eine derartige Anordnung mit demselbenZentrum. Das damit gegebene Strukturmuster läßt die Einwirkung einer zentralen Kraft vermuten. Aus dem Zusammenhang zwischen horizontalem Verschiebungssinn und der Richtung der einzelnen Spiralen ist zu schließen, daß sich die westlich der Chaman-Verwerfung liegenden Krustenblöcke in Richtung auf das Lut-Zentrum bewegten.Derartige Verwerfungssysteme sternförmig-spiraler Anordnung scheinen kritische Punkte im heutigen tektonischen Bild der Erde zu sein, wobei das Westende der Poebene und die Banda-See zwei der auffallendsten Zentren sind. Ebenso verlaufen die pazifischen Inselbögen in Spiralen, die sich gleichfalls in solchen Zentren treffen könnten.

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Résumé Une carte des failles actives de la Perse, de l'Afghanistan, et de la Pakistan a été dressée d'après des photos-aériennes et des photos-mosaïques. Les ruptures des filets et des rivières montrent que le rejet net est presque horizontal. Cinq failles sont dextrales, et quatre sont sinistrales. Des lignes qui montrent la direction de la maximum contraction horizontale, déterminée par les failles, encerclent la Dasht Lut dépression dans la Perse orientale.

     

On the simulation of multidimensional cyclic loading with intergranular strain

A sample of soil is subjected to multidimensional cyclic loading when two or three principal components of the stress or strain tensor are simultaneously controlled to perform a repetitive path. These paths are very useful to evaluate the performance of models simulating cyclic loading. In this article, an extension of an existing constitutive model is proposed to capture the behavior of the soil under this type of loading. The reference model is based on the intergranular strain anisotropy concept and therefore incorporates an elastic locus in terms of a strain amplitude. In order to evaluate the model performance, a modified triaxial apparatus able to perform multidimensional cyclic loading has been used to conduct some experiments with a fine sand. Simulations of the extended model with multidimensional loading paths are carefully analyzed. Considering that many cycles are simulated (\(N>30\)), some additional simulations have been performed to quantify and analyze the artificial accumulation generated by the (hypo-)elastic component of the model. At the end, a simple boundary value problem with a cyclic loading as boundary condition is simulated to analyze the model response.     

Structural controls of lode-gold mineralization by mafic dykes in late-Paleozoic granitoids of the Kochkar district, southern Urals, Russia

The Kochkar gold district in the East Uralian Zone of the southern Urals is located in late-Paleozoic granite gneisses of the Plast massif. Gold mineralization is associated with tabular quartz lodes that are preferentially developed along the margins of easterly trending mafic dykes. Fabric development indicates that dykes had a profound influence on the development of shear zones in granitoids. ENE- and SE-trending dykes have been reactivated as dextral and sinistral oblique strike-slip shear zones, respectively, forming a set of approximately conjugate shear zones related to the Permian, regional-scale E-W directed shortening. Dyke-shear zone relationships in the Plast massif are the result of strain refraction due to the presence of biotite-rich, incompetent dykes in more competent granite-gneisses. Deformation and the formation of associated gold-quartz lodes occurred close to peak-metamorphic, upper-greenschist to lower-amphibolite facies conditions. Strain refraction has resulted in partitioning of the bulk strain into a component of non-coaxial mainly ductile shear in mafic dykes, and a component of layer-normal pure shear in surrounding granitoids where deformation was brittle-ductile. Brittle fracturing in granitoids has resulted in the formation of fracture permeabilities adjacent to sheared dykes, that together with the layer-normal dilational component, promoted the access of mineralizing fluids. Both ore-controlling dykes and gold-quartz lodes were subsequently overprinted by lower greenschist-facies, mainly brittle fault zones and associated hydrothermal alteration that post-date gold mineralization. Received: 15 October 1998 / Accepted: 18 August 1999     

The response of ionospheric convection in the polar cap to substorm activity

We report multi-instrument observations during an isolated substorm on 17 October 1989. The EISCAT radar operated in the SP-UK-POLI mode measuring ionospheric convection at latitudes 71°-78°. SAMNET and the EISCAT Magnetometer Cross provide information on the timing of substorm expansion phase onset and subsequent intensifications, as well as the location of the field aligned and ionospheric currents associated with the substorm current wedge. IMP-8 magnetic field data are also included. Evidence of a substorm growth phase is provided by the equatorward motion of a flow reversal boundary across the EISCAT radar field of view at 2130 MLT, following a southward turning of the interplanetary magnetic field (IMF). We infer that the polar cap expanded as a result of the addition of open magnetic flux to the tail lobes during this interval. The flow reversal boundary, which is a lower limit to the polar cap boundary, reached an invariant latitude equatorward of 71° by the time of the expansion phase onset. A westward electrojet, centred at 65.4°, occurred at the onset of the expansion phase. This electrojet subsequently moved poleward to a maximum of 68.1° at 2000 UT and also widened. During the expansion phase, there is evidence of bursts of plasma flow which are spatially localised at longitudes within the substorm current wedge and which occurred well poleward of the westward electrojet. We conclude that the substorm onset region in the ionosphere, defined by the westward electrojet, mapped to a part of the tail radially earthward of the boundary between open and closed magnetic flux, the “distant” neutral line. Thus the substorm was not initiated at the distant neutral line, although there is evidence that it remained active during the expansion phase. It is not obvious whether the electrojet mapped to a near-Earth neutral line, but at its most poleward, the expanded electrojet does not reach the estimated latitude of the polar cap boundary.     

Cosmogenic nuclide methods for measuring long-term rates of physical erosion and chemical weathering

Understanding the evolution of geochemical and geomorphic systems requires measurements of long-term rates of physical erosion and chemical weathering. Erosion and weathering rates have traditionally been estimated from measurements of sediment and solute fluxes in streams. However, modern sediment and solute fluxes are often decoupled from long-term rates of erosion and weathering, due to storage or re-mobilization of sediment and solutes upstream from the sampling point. Recently, cosmogenic nuclides such as ¹⁰Be and ²⁶Al have become important new tools for measuring long-term rates of physical erosion and chemical weathering. Cosmogenic nuclides can be used to infer the total denudation flux (the sum of the rates of physical erosion and chemical weathering) in actively eroding terrain. Here we review recent work showing how this total denudation flux can be partitioned into its physical and chemical components, using the enrichment of insoluble tracers (such as Zr) in regolith relative to parent rock. By combining cosmogenic nuclide measurements with the bulk elemental composition of rock and soil, geochemists can measure rates of physical erosion and chemical weathering over 1000- to 10,000-year time scales.     

Solar Spectral Irradiance Variability in November/December 2012: Comparison of Observations by Instruments on the International Space Station and Models

Onboard the International Space Station (ISS), two instruments are observing the solar spectral irradiance (SSI) at wavelengths from 16 to 2900 nm. Although the ISS platform orientation generally precludes pointing at the Sun more than 10?–?14 days per month, in November/December 2012 a continuous period of measurements was obtained by implementing an ISS ‘bridging’ maneuver. This enabled observations to be made of the solar spectral irradiance (SSI) during a complete solar rotation. We present these measurements, which quantify the impact of active regions on SSI, and compare them with data simultaneously gathered from other platforms, and with models of spectral irradiance variability. Our analysis demonstrates that the instruments onboard the ISS have the capability to measure SSI variations consistent with other instruments in space. A comparison among all available SSI measurements during November–December 2012 in absolute units with reconstructions using solar proxies and observed solar activity features is presented and discussed in terms of accuracy.     

Abbau von Monochlornitrobenzolen durch Pseudomonas acidovorans CA50

Degradation of Monochloronitrobenzenes by Pseudomonas acidovorans CA50 Pseudomonas acidovorans strain CA50 was used for degradation experiments with monochloronitrobenzenes in aerobic batch culture. The monochloronitrobenzenes were reduced to the corresponding monochloroanilines. The reduction only occurred with an additional carbon and nitrogen source. Chlorocatechols were found to be present. 3-Chlorocatechol accumulated in the presence of 2-chloroaniline, whereas 4-chlorocatechol was an intermediate metabolite of 3- and 4-chloroaniline. Contrary to the degradation of monochloronitrobenzenes, Pseudomonas acidovorans strain CA50 used the monochloroanilines as a sole source of carbon, energy, and nitrogen for growth. The oxidation of monochloroanilines was not repressed by the additional substrates. 2-Chloronitrobenzene was degraded with the lowest rate because of the low turnover of the intermediate metabolite 2-chloroaniline. 3-Chloronitrobenzene was completely degraded also in a mixture. A complete degradation of 4-chloronitrobenzene was achieved only when it was the sole chloronitrobenzene. The results suggest that a dechlorination and mineralization of monochlornitrobenzenes is possible, but for a final proof, further investigations will be necessary.     

地震强地面运动的特征描述

描述强地面运动特征的现行观点和发展趋势。过去十几年中,有赖于强地面运动观测数据的积累,得到一些改进的地面运动经验模型。然而,这些模型具有很大的不确定性,因为“震级-距离-土类型“”的参数化相对实际过于简单。其他一些对强地面运动有重要影响的参数,例如:近断层地区的破裂方向性、地壳波导效应、盆地响应等,没有在这些模型中得到反应。建立在地震学理论基础上,并包含了这些附加条件的地面运动数值模型已经得到开发,它们被记录到的地面运动验证是有效的,并且被用来评估过去地震的地面运动,以及对未来地震的地面运动进行预测。