The pink topaz-bearing calcite, quartz, white mica veins from Ghundao Hill (North West Frontier Province, Pakistan): K/Ar age, stable isotope and REE data

Summary In the area of the Ghundao Hill (Northern Frontier Province, Pakistan) an orange-yellow to cherry-red topaz is found in calcite, quartz, white mica veins crosscutting the schistosity of probably Silurian to Devonian gray limestones. Topaz with such a range of colours is traded as Imperial Topaz. Low fluorine contents of about 15 wt.%, oxygen isotope thermometry, K/Ar age determination on white mica, fluid inclusion data and mineral textures indicate that the topaz from Ghundao Hill crystallized at temperatures of about 230 °C during the Eocene Himalayan tectonothermal event and not from a late to postmagmatic granite-related fluid. The pink Topaz from Ghundao Hill shares the coexistence with carbonates, low fluorine content and a crystallization at low temperature and pressure during a regional tectonothermal event with the Imperial Topaz from Ouro Preto (Brazil) and from the Sanarka/Kamenka rivers (South Urals, Russia). The efficiency of topaz to remove fluorine from fluids at low temperature explains how topaz can be formed from metamorphic fluids that are typically poor in fluorine. High CO₂ activity produced in the fluids by metamorphic decarbonatisation reactions and Al buffering by white mica prevented fluorination of carbonates stabilising topaz relative to fluorite.     

Siberian CO2 efflux in winter as a CO2 source and cause of seasonality in atmospheric CO2

Over three years, we found a consistent CO₂ efflux from forest tundra of the Russian North throughout the year, including a large (89 g C m^–2 yr^–1) efflux during winter. Our results provide one explanation for the observations that the highest atmospheric CO₂ concentration and greatest seasonal amplitude occur at high latitudes rather than over the mid-latitudes, where fossil fuel sources are large, and where high summer productivity offset by winter respiration should give large seasonal oscillations in atmospheric CO₂. Winter respiration probably contributed substantially to the boreal winter CO₂ efflux. Respiration is an exothermic process that produces enough heat to warm soils and promote further decomposition. We suggest that, as a result of this positive feedback, small changes in surface heat flux, associated with human activities in the North or with regional or global warming, could release large quantities of organic carbon that are presently stored in permafrost.     

Application of thermodesorption mass spectrometry for studying proton water formation in the lunar regolith

In this paper, we report experimental data on the implantation of hydrogen ions of different energies into crystalline quartz samples. It was shown that irradiation with protons with an energy of 20 keV produces an amorphous film on the surface of a quartz sample, and irradiation with 90-keV protons results in the formation of a layer with interstitial defects and an increase in the unit-cell parameter of quartz with preservation of the crystal structure of the disturbed layer. The examination of the samples by thermodesorption mass spectrometry showed that high-energy irradiation resulted also in loosening of the surface layer and considerable expansion of high-potential adsorption sites, which was the reason for the observed peak desorption of gases. The existence of desorption peaks allowed us to calculate the activation energy of surface desorption of gas components. It was also found that an increase in irradiation energy tends to enhance the total degassing of samples.     

Experimental Study of the Product Composition of the Chelyabinsk Meteorite (LL5) Outgassing

The Chelyabinsk meteorite sample of type LL5 was subjected to calcination in the specially constructed instrument in the temperature range 200–800°C in increments of 100°C. The composition of the obtained volatile constituents was examined on a chromatograph. Detected were: CO₂, H₂O, and N₂ in concentrations of 5–40 μg/g of the sample; H₂, CO, CH₄, and H₂S in concentrations of 0.1–2.0 μg/g. By observing changes in the selected component concentrations over time (up to 90 minutes), it was concluded that chemical reactions in the system between volatile components occur directly during outgassing.

     

Raman identification of calcite grains in the Chelyabinsk meteorite

Samples of the Chelyabinsk meteorite fallen in February 15, 2013, near Chelyabinsk, Russia, are analyzed by Raman spectroscopy. Olivines (forsterite), orthopyoxenes (enstatite), plagioclases (albite), iron oxides and sulfides, as well as calcite and, possibly, parisite were identified among mineral phases. Results were verified using scanning electron microscope with an energy-dispersive system (SEM-EDX). Data were compared with available materials on calcites from ordinary meteorites.     

He implantation and concentrations in minerals and lunar regolith particles

Solar-wind erosion of rocks on the lunar surface and the implanting of solar-wind particles in minerals of lunar regolith are principally important processes of space weathering. The latter process leads to the accumulation of inert gases in mineral particles of lunar regolith. Literature data indicate that, depending on the composition and structure of the particles, the concentrations of implanted He in various minerals range within roughly three to four orders of magnitude. The lowest He implantation coefficient was determined in amorphous particles (glass), and very low implantation coefficients were also obtained in experiments on He implantation in glass (obsidian).     

Spectral and structural properties of carbon nanoparticles synthesized in natural and anthropogenic processes

In this contribution, we considered the character of carbon nanoparticle formation in the cosmos and during volcanic eruptions of a certain type and compared it with existing methods of synthesis in nanotechnology. Using the methods of electron diffraction and Raman spectroscopy, we investigated nanodiamond samples synthesized by hydrodynamic cavitation in various hydrocarbon liquids. Different forms of nanometer-sized carbon were distinguished, including complex fullerenes, nanodiamonds, and a face-centered cubic (fcc) carbon phase. The synthesized nanodiamonds were doped with silicon, their photoluminescence spectra were analyzed, and application of the results for geochemistry and cosmochemistry were discussed.     

Broadband Registration of High-Frequency Seismic Noise for Studying Tidal Effects

The possibility of registering high-frequency seismic noise in a broadband frequency range (f = 5–400 Hz) has been considered. The use of an accelerometer on based on the S mode of bending vibrations increases the sensitivity and expanses the frequency range. The operating principle of the accelerometer and its main technical characteristics have been described. Pilot registration of seismic noise was organized at Nachiki seismic station in Kamchatka. The comparative results of tidal effects in seismic noise have been presented according to the data of the broadband accelerometer (f = 5–400 Hz) and resonance sensor (f₀ = 30 Hz) during long-term registration on a common base.     

Temporary seismological observations in the area of the 2012–2013 Tolbachik Fissure Eruption: Results

The seismicity that accompanied the Tolbachik Fissure Eruption was recorded by additional seismic stations that were installed in the southern Klyuchevskoi Volcanic Cluster area in January to October 2013. We used broadband (0.033–50 Hz) three-component digital Guralp CMG-6TD seismometers. This temporary network provided seismicity data at a lower energy level than can be done using the regional seismograph network of Kamchatka. The processing of the resulting digital records supplied data for compiling a catalog of over 700 M _L = 0–3.5 (K _S = 1.5–8.5) earthquakes, which is an order of magnitude greater than the number of events located by the regional network for the same period of time. The seismicity in the area of Ploskii Tolbachik Volcano was found to concentrate mostly in spatially isolated areas during the eruption. The main isolated clusters of earthquakes were identified both in the eruption area itself and along the periphery of Ploskii Tolbachik Volcano, in the area of the Zimina volcanic massif, and in the Tolud epicenter zone; the eruption zone was not dominant in the seismicity. The region of a shallow seismicity increase beneath Ploskii Tolbachik before the eruption was not found to exhibit any increased activity during the time the temporary seismograph network was operated, which means that a seismicity inversion took place at the beginning of the eruption. We discuss the question of what the earthquake-generating features are that we have identified.     

Prolate Body Disruption by Earth at Near Flyby: Possible Scenarios

Solar System Research - In this paper, we discuss the possible disruption of a prolate ellipsoidal small body by the Earth’s tidal forces during a close flyby. An exact expression for the...