Petrophysical features of the tectonic structures of the Okhotsk continent–ocean transition zone

Petrophysical characteristics are determined for the rock complexes of the Okhotsk margin within the continent–ocean transition zone. Petrophysical maps showing the major inhomogeneities of the main tectonic elements of the studied area are constructed. Petrophysical inhomogeneities and the corresponding geophysical field anomalies are compared. A relationship between the magnetic field anomalies and subsurface rock complexes is revealed. The gravity field anomalies are related to deep inhomogeneities and are almost independent of the subsurface rock complexes of relatively low thickness.     

Mechanistic evaluation and reaction pathway of UV photo-assisted Fenton-like degradation of progesterone in water and wastewater

The mechanisms and reaction pathway of UV photo-assisted Fenton-like degradation of progesterone in water and wastewater were investigated. The reaction followed the pseudo-first-order kinetics for both the dark Fenton-like and UV photo-Fenton-like processes. The reaction kinetics of the UV photo-assisted process improved with the presence of humic acid (HA) in wastewater, due to the formation of Fe(III)-HA complexes which enhanced Fe(II) production by a ligand-to-metal charge transfer. The UV photo-assisted process reduced the amount of ferric required to completely degrade progesterone by 60 % and lowered the activation energy to 42 kJ/mol compared to 104 kJ/mol for the dark Fenton-like process. Complete degradation of progesterone was achieved through a multi-step process involving several intermediate compounds.     

Long-Term Geochemical Monitoring of the Source of the Angara River (Runoff from Lake Baikal)

The long-term data (1950–2017) on the chemical composition of the water from the source of the Angara River, which is the only run-off from Lake Baikal, a large and clean fresh water reservoir, are presented. The absence of water contamination despite the anthropogenic influence is shown. The similarity and constancy of the current composition of the waters in the lake and the Angara River are recorded. It is recommended to continue geochemical studies of this unique world heritage site.     

Occurrence Forms of Carbon,Sulfur, and Noble Metals in Deposits of the Black-Shale Formation by the Example of the Degdekan Gold-Ore Deposit (Northeastern Russia)

Pyrite crystals and ore-bearing shales of the Degdekan deposit were studied by means of XPS, SEM–EDX, EPMA, and AAS. Five peaks of carbon organic forms were identified, conforming to polymer compounds containing either double bonds of carbon or alkyne groups and compounds containing C–OH and C=O bonds, as well as, probably, small amounts of S-containing compounds and those with functional groups of carboxylic acids. Sulfate prevails over sulfite in pyrites; among the surface sulfide forms, disulfide prevails over monosulfide; the presence of polysulfide is registered. The occurrence of various chemical forms of sulfur on the surface might provide for concentrating of microelements including the noble metals (NMs) in their surface-bound forms. The regular behavior of NMs (Au, Pt, Pd, and Ru) depending on the grain sizes (specific surfaces) of pyrite crystals along with the narrow range of the ratios of structural and surface components of the concentrations of different NMs points to NM coprecipitation with pyrite during the same productive stage. No capture of NM-containing carbonaceous phases took place, which should violate the regularity of Au distribution in pyrites of the Sukhoi Log deposit.     

Cosmogenic Substances in the Zhamanshin Crater

Using high-resolution analytical electron microscopy, heterogeneous fragments of cosmogenic substances, such as nickelphosphide Ni₃P and the unnamed intermetallide ZnAl₂, are detected for the first time for a large meteorite crater, the Zhamanshin circular structure. Due to the impossibility of simultaneous finding these phases in the same meteorite, an assumption is made on the cometary nature of the impactor of the Zhamanshin crater.     

Geological and Isotope–Geochemical Criteria for the Existence of the Ancient Continental Crust in Basement Complexes of Primorye

The problem of the development of the ancient continental crust in the Primorye Region is discussed. It is substantiated by geological and isotope-geochemical criteria: a granite–metamorphic mineral composition of different-aged terrigenous deposits and pelagic cherts, occurrence of arkoses, as well as Proterozoic model age datings of sedimentary complexes and the occurrence of early Proterozoic zircons and monazites. The manifestation of potassium, high-Ba, LREE- and Nb-rich basite–ultrabasite magmatism, typical of Sino-Korean and Okhotsk Ba-bearing nuclears, of lengthy age intervals (Jurassic–Paleogene) in Primorye and the Amur Region is an important criterion.