Microwave radiation from magnetic stars

Cyclotron microwave emission from magnetic stars is considered, assuming that they have coronae with the temperatureT10⁷ K and the emission measureEM10⁵⁴ cm^–3. It has been shown that the cyclotron radiation from a star with a dipole magnetic field has a specific spectrum with a maximum in the frequency rangesv _o/2 >v >sv _o/2 (s being the number of cyclotron harmonic, andv _o the gyrofrequency corresponding to the polar magnetic field) and radiation flux decreasing towards lower frequencies asv _4/3. The frequency of the spectrum maximum depends on the angle between the line-of-sight and the magnetic axis of the star. The observed radiation from a rotating magnetic star can be modulated with a modulation depth of about 0.2 at frequencies near maximum. The radiation is partially circularly-polarized in the sense of an extraordinary mode. The degree of polarization is almost constant at frequenciesv >sv _o/2 and increases with frequency atv >sv _o/2. The estimation of cyclotron radio fluxes of the nearest magnetic stars shows that they are observable in microwaves by means of modern radio astronomy.     

Stratigraphy of the Okhotsk–Chukotka Belt in the Headwaters of the Malyi Anyui River (the Vicinity of Kupol Deposit): U–Pb and 40Ar/39Ar Age Data

Doklady Earth Sciences - U–Pb and 40Ar/39Ar age data obtained for volcanic rocks of the Okhotsk–Chukotka Belt in the headwaters of the Malyi Anyui River (the vicinity of Kupol deposit)...     

The First Data of U/Pb and 40Ar/39Ar Dating of the Pre-Dzhugdzhur Volcanics: New Evidence of Time Diversity in the Formation of Individual Sectors of the Okhotsk–Chukotka Volcanogenic Belt

Doklady Earth Sciences - The first data of U/Pb and 40Ar/39Ar dating of volcanogenic rocks of the Pre-Dzhugdzhur volcano-tectonic trough (PDVT) of the Okhotsk–Chukotka volcanogenic belt...     

Russian school contribution to the birth and development of neotectonics

Study of young tectonic movements began at the end of XIXth century and is connected with the names of scientists from various countries. A valuable contribution to development of this branch of science was made by Russian school beginning with works by M. V.Lomonosov in the XVIII century. In XIX century this trend was successfully developed by A. P.Karpinsky, A. P.Pavlov, at the beginning of XXth century - V. A.Obruchev, N. I.Andrusov, A. D.Arkhangelsky, A. L.Reingard. Study of neotectonics in the USSR spread especially widely in the Soviet period (20–40ies) owing to industrial development of the country. Works by V. A.Obruchev, G. F.Mirchink and other Soviet scientists of that period contributed much to formation of a new branch of science — neotectonics.

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Zusammenfassung Untersuchungen jungtektonischer Bewegungen begannen am Ende des neunzehnten Jahrhunderts und sind verbunden mit den Namen von Wissenschaftlern aus verschiedenen Ländern. Ein wertvoller Beitrag zur Entwicklung dieser Seite der Wissenschaft wurde von der russischen Schule — beginnend mit den Arbeiten von M. V.Lomonosov im XVIII. Jahrhundert — geleistet. Im neunzehnten Jahrhundert wurde diese Richtung erfolgreich durch A. P.Karpinsky und A. P.Pavlov weitergeführt; Anfang des 20. Jahrhunderts dann von V. A.Obruchev, N. I.Andrusov, A. D.Arkhangelsky, Reingard. Neotektonische Studien entwickelten sich besonders während der sovietischen Ära. Dies geschah in Verbindung mit der industriellen Entwicklung des Landes.Die Arbeiten von V. A.Obruchev, G. F.Mirchink und anderen Wissenschaftlern dieser Periode leisteten einen großen Beitrag zur Entstehung des neuen Wissenschaftszweiges — Neotektonik.

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Résumé L'étude des mouvements néotectoniques, qui a débuté à la fin du XIX^e siècle, est liée aux noms de savants de pays différents. L'école russe, avec les travaux de M. V. Lomonosov (XVIII^e siècle), a apporté une importante contribution au développement de cette branche des connaissances. Au XIX^e siècle, cette direction de recherches s'est développée avec A. P. Karpinsky, A. P. Pavlov et au début du XX^e siècle - avec V. A. Obruchev, N. I. Andrusov, A. D. Arkhangelsky et A. L. Reingard. L'étude de la néotectonique en URSS s'est spécialement répandue au cours des années 20–40 gràce au rapide développement industriel du pays. Les travaux de V. A. Obruchev, G. F. Mirchink et d'autres savants soviétiques de cette période ont beaucoup contribué à la formation d'une nouvelle branche de la science-la néotectonique.

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Largest Phanerozoic provinces of silicic volcanism: Tectonic position and genetic prerequisities

This paper presents a brief overview of largest Phanerozoic volcanic provinces of the Earth, which comprise the substantial volumes (over 10⁵ km³) of silicic extrusive rocks. The provinces of this kind may re- present a separate geodynamic class, having the volume comparable to that of intraplate Large Igneous Provinces (LIPs), and being formed in convergent margin settings. The thermal energy preserved in the crust after a previous major magmatic event is considered to be an important factor affecting the volume of crust-derived magmas and playing a significant role in the formation of large provinces of silicic volcanism.     

Amplitude of Secular Geomagnetic Variation in Late Cretaceous Based on Paleomagnetic Studies of the Okhotsk–Chukotka Volcanic Belt from Upper Reaches of Malyi Anyui River,West Chukotka

Izvestiya, Physics of the Solid Earth - Abstract—A paleomagnetic study of the Okhotsk–Chukotka belt volcanics exposed in the region of the Kupol field (~66.9° N, 170.1° E) has...     

Chronology of Quaternary terrace deposits at the locality Hohle Gasse (Pratteln,NW Switzerland)

The Quaternary stratigraphy of the Alpine Foreland consists of distinct terrace levels, which have been assigned to four morphostratigraphic units: Höhere (Higher) Deckenschotter, Tiefere (Lower) Deckenschotter, Hochterrasse (High Terrace) and Niederterrasse (Lower Terrace). Here, we focus on the terrace gravels at Hohle Gasse, SSE of Pratteln near Basel, which are mapped as Tiefere Deckenschotter. Petrographic and morphometric data established from clasts allowed to infer the transport mechanisms and sources of the gravels. Sedimentological analyses indicate that the gravels were transported by a braided river and deposited in a distal glaciofluvial setting. In addition, it can be shown that the majority of the clasts display multiple reworking and only a minority maintained a distinct glaciofluvial shape. Cosmogenic multi-isotope dating using ¹⁰Be and ³⁶Cl allowed direct dating of the sediments at the study site. A depth-profile age of \(2 70_{ - 1 90}^{ + 8 30}\) ka for ¹⁰Be was achieved for the deposits at Hohle Gasse. Unfortunately, no age could be modelled from the ³⁶Cl concentrations as the blank correction was too high. Furthermore, this age proves that the studied terrace level should be assigned to the morphostratigraphic unit Hochterrasse.     

New data on the metamorphic petrology of rocks from the Kuekvun uplift (Northern Chukchi Peninsula)

The metamorphic rocks of the Kuekvun uplift are gneisses and schists that developed after Mid-Paleozoic sedimentary sequences, which consist mostly of terrigenous rocks with minor amounts of intermediate to mafic igneous rocks and subordinate carbonates. Two plagiogneiss samples that were selected for detailed analysis were taken from the axial part and flanks of the uplift. The mineral paragenesis and composition of coexisting garnet, biotite, and staurolite indicate a metamorphic temperature of 560–600°C and pressure of 2.5–4 kbar, corresponding to a depth of 8–12 km. These conditions suggest a relatively high geothermal gradient (about 60°C/km), approaching that for contact metamorphic aureoles. Garnets from the axial zone and flanks of the uplift display a similar zoning pattern. The difference is the presence of compositionally contrasting Ca-rich rims in garnets from the axial zone. These rims may be either the result of zoning within the entire metamorphic complex or a late local overprint, e.g., crystallization of granitic plutons, which are common within the study area.