Rock salt mass in the Paleoproterozoic sequence of the Onega trough in Karelia (from the Onega parametric well data)

A thick (200 m) rock salt mass covering Late Archean granitoids was exposed for the first time in the Early Proterozoic volcanogenic-sedimentary formations in the Onega trough of the east Baltic Shield by the Onega parametric well. The mineral composition of salts, their geochemical features, and the isotopic composition of carbonate carbon and oxygen have been studied. After fluid inclusions present in salts, their metamorphism temperature and isotopic composition of helium and argon were determined. The obtained results give evidence of the fact that rock salts and magnesites associated with them were formed in an evaporate basin with participation of deep crustal processes. The age of the underlying granitoids (2.716 ± 9 Ma) is determined using the Pb—Pb method.     

Energy Spectra of Cosmic-Ray Protons and Nuclei Measured in the NUCLEON Experiment Using a New Method

Astronomy Reports - Some results of studies of cosmic rays obtained during the NUCLEON space experiment in 2015–2017 are presented. This experiment was intended for direct measurements of the...     

The Nikolaevsky base-metal skarn deposit, Primorye, Russia

The study of the mineralogical and geochemical features of ores and their textural and structural relationships at the Nikolaevsky base-metal skarn deposit allowed us to establish the succession of mineral assemblages and to ascertain the complex distribution of elements in minerals, ores, and orebodies resulting from nonuniform development of metasomatic zones in the single ore-metasomatic process. The vertical mineralogical and geochemical zoning of the deposit is expressed in the replacement of economic Pb-Zn mineralization at the lower levels of the skarn orebodies with Ag-Pb-Zn mineralization at the upper levels of the major Vostok-1 orebody located at the contact of limestone and felsic volcanics and the block orebodies at the lower level of felsic volcanic rocks. Au-bearing vein Pb-Ag-Sb mineralization occurs in the near-surface zone of the deposit. Three mineralogical types of ores have been identified: sulfide-hedenbergite, quartz-carbonate-sulfide, and sulfide. The zonal distribution of these types within orebodies is combined with variations in mineralogy and in the distribution of major and minor elements. The statistical processing (the Geokhimiya-1 program) of 96 chemical analyses of monomineralic galena and sphalerite samples taken from skarn showed that an intimate Pb ? Bi assemblage is characteristic of the lower levels, whereas a Ag Bi assemblage is typical of the upper levels. The elemental assemblages correspond to definite mineral assemblages, determining the mineralogical and geochemical zoning of the deposit.     

Primary cosmic-ray nucleon spectrum in the energy range 40–400 TeV reconstructed from the secondary gamma-ray spectrum in the stratosphere

We present the spectrum of all primary cosmic-ray nucleons in the energy range 40–400 TeV reconstructed from the spectra of gamma rays recorded along with charged particles at an altitude of 30 km in the stratosphere in the RUNJOB balloon experiment. Gamma rays are produced by the interaction of primary cosmic-ray particles with atomic nuclei of the residual atmosphere and are a component whose spectrum follows the nucleon spectrum at the atmospheric boundary in the approximation of quasi-scaling models. Comparison of the nucleon spectrum with the proton spectrum indicates that the contribution of nucleons from nuclei increases toward the 100-TeV energy region compared to the 1-TeV region. This result confirms the conclusions reached in the JACEE, SOKOL, ATIC-2, and KASCADE experiments: the fraction of helium nuclei and, possibly, heavier nuclei in the primary cosmic-ray flux increases with energy.     

Dependence of the position of the knee in the Galactic cosmic ray spectrum on the explosion energy distribution of supernovae

The position of the knee in the Galactic cosmic ray (GCR) spectrum is shown to depend on the explosion energy distribution function of supernovae (SN). The position of the knee in the GCR spectrum can be quantitatively explained by the dominating contribution of hypernovae with explosion energies of (～30–50)×10⁵¹ erg, the fraction of which must be no less than 1% of all SN. The model reproduces the main features in the spectrum of all particles measured in extensive air shower (EAS) experiments: the knee in the spectrum of all particles at energy of about 3 PeV, the change in slope by δ_γ ～ 0.3–0.5 after the knee point, and the steepening of the spectrum near 10¹⁸ eV. The model predicts a smooth knee if the SN explosion energy distribution is universal and a sharp knee if the hypernovae represent a separate class of events. The suggested model of the GCR spectrum is essentially based on the assumption that a spread in explosion energies exists and that the assumptions of the standard model for the CR acceleration in supernova remnants are valid.