The 2006 (Мw 8.3) and 2007 (Мw 8.1) Simushir Earthquakes and the 2011 Tohoku Megaearthquake (Мw 9.0): Tectonic Stresses and Development of the Seismic Process     

T. K. Zlobin 《Doklady Earth Sciences》2018,480(1):599-601

The peculiarities of catastrophic earthquakes that occurred in the Northwest Pacific region on January 13, 2007, and January 15, 2007, east of the Kuril Islands and the Tohoku megaearthquake of March 11, 2011, east of Japan are considered and analyzed. It is revealed that these earthquakes, apart from the fact that they occurred in the transition zone from the Pacific to island arcs and the Eurasian continent, have common features and similar characteristics. The seismotectonic slip in the source of the chronologically first event, the 2006 Kuril earthquake, was a gentle thrust, while that of the second event of January 13, 2007, was a downthrow beneath the Kuril deep trench.  相似文献   

Dynamics of the Formation of Globular Silica Particles according to Dynamic Light Scattering     

D. V. Kamashev  A. M. Askhabov 《Doklady Earth Sciences》2018,480(1):615-617

For the first time, the dynamics of the origination and growth of monodispersion spherical silica particles is studied by dynamic light scattering in the real-time mode. Experimental changes in the particle size and intensity of scattering during their formation and growth indicate the hierarchical formation of silica globules under various mechanisms of aggregation of particles.  相似文献   

Neoproterozoic Rare-Metal Subalkali Leucogranite from the Northern Yenisei Ridge     

A. D. Nozhkin  V. V. Reverdatto 《Doklady Earth Sciences》2018,480(1):580-586

Petrochemical study and U–Pb SIMS (SHRIMP–II) zircon analyses of subalkaline leucogranite of the Khariusikha Massif have been carried out. They have revealed for the first time a rare-metal mineralization. The elevated concentrations of rare elements (wt %) are Nb (0.5–0.7), Ta (0.12–0.16), REEs (0.08–0.24), Y (0.06–0, 1), Zr (2.3–2.6), Hf (0.1–0.12), U (0.05–0.1), and Th (0.08–0.1) and are confined to albitized granites. The main mineral phases concentrating the rare elements, U and Th, are tantalo–niobates: fergusonite, euxenite, U–pyrochlore, tantalite, as well as thorite, monazite, zircon, and sphene. These minerals associate with cassiterite, sulfides, and gold. The simultaneity of the intraplate granitoid magmatism (753 ± 4 Ma) and bimodal rhyolite–basalt volcanism (753 ± 6 Ma) in the neighboring rift structure has been demonstrated. Presumably, the Neoproterozoic rifting and intraplate magmatism relate to the plume activity that caused the supercontinent Rodinia to break up.  相似文献   

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

V. I. Grebenshchikova  M. I. Kuzmin  O. A. Proydakova  O. V. Zarubina 《Doklady Earth Sciences》2018,480(2):735-740

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.  相似文献   

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)     

V. L. Tauson  R. G. Kravtsova  V. V. Akimov  S. V. Lipko  A. M. Spiridonov  A. E. Budyak  I. Yu. Voronova  O. Yu. Belozerova  K. Yu. Arsentev 《Doklady Earth Sciences》2018,478(1):92-99

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.  相似文献   

Cosmogenic Substances in the Zhamanshin Crater     

T. A. Gornostaeva  A. V. Mokhov  P. M. Kartashov  O. A. Bogatikov 《Doklady Earth Sciences》2018,478(2):204-207

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.  相似文献   

The Late Silurian Age of the Reference Aralaul Granosyenites–Granite Massif (Northern Kazakhstan)     

K. E. Degtyarev  A. A. Tretyakov  A. B. Kotov  E. B. Salnikova  M. V. Luchitskaya  V. P. Kovach  K.-L. Wang 《Doklady Earth Sciences》2018,479(1):275-278

This work presents the results of U–Pb geochronological studies of alkaline granites of the Aralaul complex of Northern Kazakhstan, which allow one to substantiate their Late Silurian (420 ± 4 Ma) age. Taking into consideration the previously obtained data, we propose a new development scheme of Paleozoic granitoid magmatism in Northern Kazakhstan, which includes Late Ordovician granite–granodiorite (Zerenda and Krykkuduk), Early Silurian granite–leucogranite (Borovoe and Karabulak), Late Silurian granosyenites–granite (Aralaul), and Early Devonian (Balkashino and Orlinogorsk) complexes.  相似文献   

The Hirnantian δ<Superscript>13</Superscript>C Positive Excursion in the Nabiullino Section (South Urals)     

R. R. Yakupov  T. M. Mavrinskaya  I. V. Smoleva 《Doklady Earth Sciences》2018,478(2):199-203

The upper Sandbian, Katian, and Hirnantian complexes of conodonts in the upper Ordovician section of the western slope of the Southern Urals near the village of Nabiullino were studied. The δ¹³C positive excursion with a maximum of 3.3‰ associated with the global Hirnantian isotopic event, HICE, was fixed for the first time. This excursion shows the beginning of the Hirnantian stage in the terrigenous–carbonate section of the upper Ordovician in the Southern Urals. It coincides with the first occurrence of the Hirnantian conodont species of Gamachignathus ensifer and the conodonts of shallow-water biophacies, Aphelognathus-Ozarkodina, reflecting the global glacio-eustatic event.  相似文献   

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

S. O. Maksimov  V. G. Sakhno 《Doklady Earth Sciences》2018,478(1):36-42

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.  相似文献   

Faults and Source Parameters of Earthquakes in the Baikal Rift Zone: Dip Angles of Fault Planes     

V. M. Dem’yanovich  A. V. Klyuchevskii 《Doklady Earth Sciences》2018,479(2):433-438

Analysis of gentle, intermediate, and steep dip angles of fault planes in earthquake sources of the Baikal region is carried out with the slips in seismic sources being taken into account. The areas where normal faulting slips at steep, intermediate, and gentle angles took place are distinguished, and this can be interpreted as transformation of a steep dip to gentle one. It is found that the increase in energy class is accompanied by the number of earthquakes with steep dip angles, whereas the proportion of earthquakes with intermediate angles decreases, and the fraction of earthquakes with gentle angles remains quasi-stable and small.  相似文献