Calcic hydrosilicate metasomatic rocks at the Gumeshevsk skarn-porphyry copper deposit in the central Urals,Russia

The body of hydroxylellestadite metasomatic rock penetrated by a borehole drilled at the Gumeshevsk deposit at depths of 530–534 m includes a thin interval of younger lower temperature tobermorite-plombierite metasomatic rock with subordinate amounts of Ca-Si gel, tacherenite, cubic lime, and thaumasite. Hydroxylellestadite has never before been found in calc skarns. The hydroxylellestadite metasomatic rock is cut by gypsum and fukalite veinlets, and the tobermorite-plombierite metasomatic rock is intersected by thaumasite veinlets. The pristine rock of the metasomatics was marble, and the metasomatic rock replaced andradite-bearing wollastonite skarn (with wollastonite replaced by foshagite). The ore minerals (chalcopyrite, valleriite, sphalerite, and others) were formed after the hydroxylellestadite metasomatite but most probably before the tobermorite-plombierite metasomatic rock and the veinlets of calcic minerals. The metasomatic rock was produced at significant variations in the oxygen, sulfur, and carbon dioxide fugacities. The composition of the hydroxylellestadite is, according to its microprobe analysis, as follows (wt %): SiO₂ 17.10, TiO₂ 0.01, Al₂O₃ 0.02, FeO 0.20, MnO 0.00, MgO 0.04, CaO 55.40, Na₂O 0.14, K₂O 0.09, P₂O₅ 0.12, CO₂ 1.90 (chemical analysis), SO₃ 21.60, F 0.16, Cl 0.14, total 96.92. The plombierite (SiO₂ 43.8–44.1 wt %, CaO 30.5–31.1 wt %) in the metasomatic rock notably differs from rare plombierite (SiO₂ 48.18 wt %, CaO 39.19 wt %) contained in the veinlets of thaumasite (SiO₂ 12.70 wt %, CaO 30.69 wt %, SO₃ 17.78 wt %).     

Sudden stratospheric warmings: the role of normal atmospheric modes

The role of normal atmospheric modes in the beginning and development of sudden stratospheric warming (SSW) events is studied on the basis of calculations with the use of the general circulation model of the middle and upper atmosphere. The analysis of the effect of a phase of quasi-biennial oscillations on the dynamics of the extratropical stratosphere has shown that the conditions for SSW commencement are more favorable and the SSW events are more intense during the easterly phase of these oscillations as compared to the westerly phase. The conclusion has been drawn that fundamental normal atmospheric modes can be recorded in the temperature field at mesopause altitudes during ground-based optical measurements.     

Multidisciplinary Investigation of the Transform Fault Zones Doldrums and Vema during Cruise 45 of the R/V “Akademik Nikolaj Strakhov”

Oceanology - Herein we provide information on the integrated geological, geophysical, sedimentological, paleoceanographic, hydrophysical and biological investigations in the Central Atlantic during...     

Evidence for Granitoid Magmatism and the Composition of the Silicic Melt in the Gabbroid Assemblage of the Mid-Atlantic Ridge at 13° N: New Data on Melt Inclusions

Doklady Earth Sciences - Despite the local occurrence of silicic magmatism during the formation of the oceanic crust, the nature of felsic granitoid veins (“oceanic plagiogranite”)...     

Seasonal and nighttime behaviors of emissions of hydroxyl and the atmospheric system of molecular oxygen of the midlatitude mesopause

Based on observations of mesopause emissions, namely, emissions of hydroxyl (band (6-2)) and molecular oxygen (band (0-1) of the atmospheric system), their systematic nighttime and seasonal variations are determined at Zvenigorod Observatory in 2000–2008. It is shown that the intensity of hydroxyl emission decreases during the entire night or first half-night, probably due to the influence of the chemical sink of atomic oxygen on the nighttime behavior of hydroxyl emission. The nighttime behavior of the intensity of molecular oxygen emission is explained by the action of atmospheric tides. The seasonal behavior of emissions is characterized by two minima, in April–May and December; it is caused by the annual behavior of the atomic oxygen content, temperature, and atmospheric density in the emitting layer. Based on the emission data, we determined the seasonal variations of atomic oxygen at heights of ∼87 km (maximum of hydroxyl emission) and ∼95 km (maximum of molecular oxygen emission).     

Geological and Geophysical Studies of the Charlie Gibbs Fracture Zone (North Atlantic)

Doklady Earth Sciences - The geological and geophysical data obtained during the 50th cruise of R/V Akademik Nikolaj Strakhov on the Charlie Gibbs megatransform system structure...     

The regular nocturnal course of temperature in the midlatitude mesopause region according to hydroxyl airglow measurements

Using ground-based spectral measurements in the near-infrared range at the Zvenigorod scientific station of the Institute of Atmospheric Physics (56° N, 37° E) for 2000–2013, we obtained average nighttime changes in rotational and vibrational temperatures of hydroxyl with its emission layer localized at mesopause heights. The rotational temperature reflects the kinetic temperature of the emission layer of the atmosphere. The analysis made it possible to determine the characteristics of the first three harmonics of diurnal temperature dynamics in the mesopause region both with and without altitudinal oscillations of the OH emission layer. In both cases, the second and third harmonics are statistically significant: their amplitudes are ～1 K and the phases of their first maxima are near 0300 and 0130 local solar time.     

Calcioolivine, γ-Ca<Subscript>2</Subscript>SiO<Subscript>4</Subscript>, an old and New Mineral species

Calcioolivine has been included into the MDI mineral database in the list of grandfathered minerals. Its history, together with related artificial compounds, is extremely complex: various minerals and compounds received this name, including natural orthorhombic Ca orthosilicate. In this paper, the crystal structure and properties of natural calcioolivine are described for the first time. The new mineral has been found at Mt. Lakargi, Upper Chegem Plateau, the northern Caucasus, Kabarda-Balkaria Republic, Russia. It has been identified in skarnified, primary carbonate xenoliths entrained by middle to late Pliocene silicic ignimbrites of the Upper Chegem caldera. These xenoliths of a few centimeters to a few meters in size are located close to the volcanic vent. Calcioolivine rims relics of larnite and occurs as relict grains among crystals of spurrite, rondorfite, wadalite or secondary hillebrandite, afwillite, thaumasite, and ettringite. Hillebrandite is the major product of alteration of calcioolivine; larnite is relatively more resistant to low-temperature alteration. Spurrite, larnite, tilleyite, kilchoanite, cuspidine, wadalite, rondorfite, reinhardbraunsite, lakargiite (CaZrO₃), members of ellestadite series, afwillite, ettringite, katoite, and thaumasite are associated minerals. It is inferred that calcioolivine has been produced as a result of interaction of host carbonate rocks in xenoliths with volcanic lava and gases during eruption. The name calcioolivine was approved by the Commission on New Minerals and Mineral Names, International Mineralogical Association, September 6, 2007 (no. 07-B).