Ongonite from Ongon Khairkhan,Mongolia

Summary Albite-topaz kerotophyres, termed ongonites, were discovered byV. I. Kovalenko and coworkers at Ongon Khairkhan in Mongolia in 1970. The type area was revisited, described, resampled, the new data is compared with the earlier data and that from similar rocks elsewhere (Beauvoir and Cinovec granites; Macusani glass).Ongonites are fluorine-rich peraluminous sodic two feldspar granitoids with orthoclase and albite phenocrysts, high modal and normative albite content and the presence of topaz as common accessory mineral. They contain variable amounts of lithium micas or muscovite. Chemically, ongonite is similar to highly fractionated S-type or ilmenite series granitoids. In the type area, F-rich water-poor ongonite melts have intruded to a high crustal level.Ongonite displays a long history of subsolidus reactions and hydrothermal alteration. The hydrothermal alteration may be linked to a spatially associated quartz-wolframite stockwork not genetically related to ongonite. Ongonite has a low W content and an elevated Sn content despite a lack of association with Sn deposits.

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Ongonite von Ongon Khairkhan, Mongolei

Zusammenfassung Albit-Topas-Keratophyre, auch als Ongonite bezeichnet, wurden 1970 von V. E. Kowalenko und Mitarbeitern bei Ongon Khairkhan in der Mongolei entdeckt. Die TypLokalität wurde beschrieben und beprobt und die neuen Daten werden mit den früher erhaltenen, und denen von ähnlichen Gesteinen in anderen Bereichen (die Granite von Beauvoir und Cinovec, das Glas von Macusani) verglichen.Ongonite sind Fluor- und Aluminiumreiche (Peraluminous), zwei-Feldspat-Natriumgranitoide mit idiomorphen Orthoklasen und Albit, hohem modalem und normativem Albitgehalt, und Topas als verbreitetem Nebenmineral. Sie führen wechselnde Gehalte von Lithiumglimmern oder Muskovit. Chemisch sind Ongonite stark fraktionierten S-Typ Granitoiden vergleichbar oder auch Granitoiden der Ilmenit-Serie. Im Gebiet der Typlokalität sind fluorreiche wasserarme Ongonit-Schmelzen in ein hohes Krustenniveau intrudiert worden.Ongonite zeigen eine lange Geschichte von Subsolidusreaktionen und hydrothermaler Umwandlung. Die hydrothermale Umwandlung kann mit einem räumlich assoziiertem Quarz-Wolframit Stockwerk in Beziehung gesetzt werden, das genetisch nicht mit den Ongoniten zusammenhängt. Ongonit hat einen niedrigen Wolframgehalt und einen erhöhten Zinngehalt, obwohl keine Assoziation mit Zinnlagerstätten zu beobachten ist.

     

Coronal mass ejection associated with the stationary post-flare arch of 21–22 May 1980

By using a combination of X-ray (HXIS), H (Haleakala), white-light corona (Solwind), and zodiacal light (Helios) images on 21–22 May, 1980 we demonstrate, and try to explain, the co-existence of a coronal mass ejection with a stationary post-flare coronal arch. The mass ejection was seen, both by Solwind and Helios, in prolongation of the path of a powerful spray, whereas the active region filament did not erupt. A tentative comparison is made with other occurrences of stationary, or quasi-stationary post-flare coronal arches.     

The Huelva (Spain) Tsunami-Ready Station and Its Interaction with Storm Emma (March 2018)

Abstract

The sea level station operating since 1996 at Mazagón (Huelva, Spain) has been progressively upgraded to fit tsunami warning requirements, due to its location in one of the main regions at risk. Its radar water level sensor was complemented in 2017, with the addition of a pressure sensor. The performance of both sea level sensors and their response to sea level oscillations, at different frequencies, is assessed. Particular emphasis is put on the effect of extreme events, such as Storm Emma, when alternative methods to obtain 1-min data are tested, in contrast to the one based on arithmetic means. The overall differences are small, for the whole period of study (centered-root-mean-square-error below 1?cm, for 5-min, and hourly data; similar tidal parameters and sea level oscillations with periods between 30?s and 5?min). However, during Storm Emma, the pressure sensor presents sensibly lower readings than the radar, with the centered-root-mean-square-error rising to 80?mm on the March 2^nd 2018. A new method to compute 1-min data, based on medians, reduced this value to 10?mm for the same day.     

The dynamics of the carbon cycle in the surface water of the Norwegian Sea

Historical data of total dissolved inorganic carbon (C_T), together with nitrate and phosphate, have been used to model the evolution of these constituents over the year in the Atlantic water of the Norwegian Sea. Changes in nutrient concentration in the upper layer of the ocean are largely related to biological activity, but vertical mixing with the underlying water will also have an impact. A mixing factor is estimated and used to compute the entrainment of these constituents into the surface water from below. After taking the mixing contribution into account, the resulting nutrient concentration changes are attributed to biological production or decay. The results of the model show that the change in C_T by vertical mixing and by biological activity based on nutrient equivalents needs another sink to balance the carbon budget. It cannot be the atmosphere as the surface water is undersaturated with respect to carbon dioxide and is, thus, a source of C_T in this region. Inasmuch as the peak deficit of carbon is more than a month later than for the nutrients, the most plausible explanation is that other nitrogen and phosphate sources than the inorganic salts are used together with dissolved inorganic carbon during this period. As nitrate and phosphate show a similar trend, it is unlikely that the explanation is the use of ammonia or nitrogen fixation but rather dissolved organic nitrogen and phosphate, while dissolved organic carbon is accumulating in the water.     

The humin structure of mucilage aggregates in the Adriatic and Tyrrhenian seas: hypothesis about the reasonable causes of mucilage formation

Sixteen mucilages sampled in the Adriatic and Tyrrhenian seas during 1999–2001 were characterised using spectroscopic [Fourier transform infrared spectroscopy (FTIR); colorimetric], chromatographic [thin-layer chromatography (TLC)], and elemental analysis techniques. Most samples contained comparable fractions of organic and inorganic compounds, with the exception of a few samples where the inorganic fraction was greater than the organic fraction. Carbohydrates were important in the samples rich in organic matter, while carbonate and silica (quartz and biogenic silica) were the most important constituents of the inorganic fraction. Carbonate and silica were the only important constituents of the samples with a very low organic content.According to chemical analyses, mucilage aggregates show the typical structure of humin—the insoluble fraction of the humic substance. Classification of mucilage samples as humin-like compounds, together with a reexamination of the factors involved in the formation of organic aggregates in marine environment, has led to the formulation of a reasonable hypothesis for mucilage formation.     

Fluctuations of CaFz(Eu) scintillator background

Background signal of the scintillation detector routinely used for atmospheric Kr-85 counting follows fluctuations, and their connection with cosmic ray variations is searched for. A strong correlation between the 27-day moving average of sunspot numbers and the background is obtained from the 1988 data.     

Solar flares: The gradual phase

One has to distinguish between two kinds of the gradual phase of flares: (1) a gradual phase during which no energy is released so that we see only cooling after the impulsive phase (a confined flare), and (2) a gradual phase during which energy release continues (a dynamic flare).The simplest case of (1) is a single-loop flare which might provide an excellent opportunity for the study of cooling processes in coronal loops. But most confined flares are far more complicated: they may consist of sets of unresolved elementary loops, of conglomerates of loops, or they form arcades the components of which may be excited sequentially. Accelerated particles as well as hot and cold plasma can be ejected from the flare site (coronal tongues, flaring arches, sprays, bright and dark surges) and these ejecta may cool more slowly than the source flare itself.However, the most important flares on the Sun are flares of type (2) in which a magnetic field opening is followed by subsequent reconnection of fieldlines that may continue for many hours after the impulsive phase. Therefore, the main attention in this review is paid to the gradual phase of this category of long-decay flares. The following items are discussed in particular: The wide energy range of dynamic flares: from eruptions of quiescent filaments to most powerful cosmic-ray flares. Energy release at the reconnection site and modelling of the reconnection process. The post-flare loops: evidence for reconnection; observations at different wavelengths; energy deposit in the chromosphere, chromospheric ablation, and velocity fields; loops in emission; shrinking loops; magnetic modelling. The gradual phase in X-rays and on radio waves. Post-flare X-ray arches: observations, interpretation, and modelling; relation to metric radio events and mass ejections, multiple-ribbon flares and anomalous events, hybrid events, possible relations between confined and dynamic flares.