Paleogeodynamics of Triassic grabens system formation in the Western Siberia     

K. S. Ivanov  Yu. V. Erokhin 《Doklady Earth Sciences》2014,458(2):1197-1200

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The Sr,Nd, and Hf isotopic geochemistry of rocks of the gabbro–diorite–tonalite association from the Eastern Segment of the Middle Urals as an indicator of the age of the continental crust in this area     

V. N. Smirnov  K. S. Ivanov  Yu. L. Ronkin  V. A. Koroteev  P. A. Serov  A. Gerdes 《Doklady Earth Sciences》2017,474(1):516-519

According to isotopic analysis of rocks of the Reft gabbro–diorite–tonalite complex (Middle Urals), gabbro and related diorite and dikes and vein-shaped bodies of plagiogranitoids, crosscutting gabbro, are similar to the depleted mantle substance in ε_Nd(T) = 8.6–9.7 and ε_Hf(T) = 15.9–17.9. Their model Hf ages are correlated with the time of crystallization. Here, the tonalites and quartz diorites constituting most of the Reft massif are characterized by lower values: ε_Nd(T) = 3.7–6.0, ε_Hf(T) = 11.1–12.7, and T _DM values significantly exceeding the age datings. This is evidence that Neoproterozoic crustal rocks were a source of parental magma for these rocks. The primary ⁸⁷Sr/⁸⁶Sr ratio in rocks of both groups is highly variable (0.70348–0.70495). The data obtained allow us to reach the conclusion that the Reft gabbro–diorite–tonalite complex was formed as a result of nearly synchronous processes occurring in the crust and the mantle within a limited area.  相似文献   

The resource potential of Russian lands for crop farming     

A. L. Ivanov  I. Yu. Savin  V. S. Stolbovoy 《Doklady Earth Sciences》2017,473(1):346-349

Geoinformational analysis shows that the fraction of lands that are optimal for farming of the main crops in Russia is about 10% of the available land at best (for summer wheat, buckwheat). For the majority of other crop cultures, this value is a few percent at most. The available resources are used very incompletely. The index of completeness of land resource potential use is no more than 10% for the majority of crops. Only in the case of soy are the available resources almost completely involved, whereas available land resources of winter wheat, grain maize, and sunflowers are used at 20–30%.  相似文献   

Eclogite trace in evolution of Late Cenozoic alkaline basalt volcanism on the southwestern flank of the Baikal Rift Zone: Geochemical features and geodynamic consequences     

A. B. Perepelov  M. I. Kuzmin  S. S. Tsypukova  E. I. Demonterova  A. V. Ivanov  Yu. D. Shcherbakov  M. Yu. Puzankov  D. Odgerel  D. Bat-Ulzii 《Doklady Earth Sciences》2017,476(2):1187-1192

Eclogitized material from the oceanic lithosphere are the most likely source of alkaline basalt magmas in the formation of Late Cenozoic volcanic areas on the southwestern flank of the Baikal Rift Zone. Basaltic trachyandesites of the early stage of volcanism (Pg₃² ~ 28–23 Ma) are rich in high field strength elements (HFSE), P₂O₅, F, Zn, Ga, Sr, Sn, and light rare earth elements (LREE); they are characterized by high values of the following ratios: Fe/Mn = 72–77, Sm/Yb = 7.7–8.5, Sr/Y = 57–63, and Ga/Sc = 2.1–2.3. At this stage, magmas are formed under conditions with a 2–8% degree of partial melting of the mantle substrate enriched with the material of the eclogite source (50–70%) (Cpx/Grt = 1.5–1.7). Basaltoid magmas of the final stage of volcanism (N₁³–N₂¹ ~ 6–4 Ma) are formed from melting (1.5–4%) of a less fertilized mantle (Cpx/Grt = 2.1–3.1, Fe/Mn = 62–71, Sm/Yb = 3.5–4.6, Sr/Y = 29–44, Ga/Sc = 1.0–1.4). The directed variations of the compositions of the successive basaltoid magmas, which were formed in the Late Cenozoic, create an “eclogite trace” in this area.  相似文献   

The first Lu–Hf zircon isotope data for gabbro–diorite–tonalite associations of the Urals     

Ronkin  Yu. L.  Smirnov  V. N.  Ivanov  K. S.  Gerdes  A. 《Doklady Earth Sciences》2017,472(1):104-108

Doklady Earth Sciences - The Lu–Hf isotope systematics of zircon from the gabbro–plagiogranite association (gabbro, diorite, tonalite, and plagiogranite), which is one of the most...  相似文献   

The Kargapole meteorite: New data on mineralogy     

Yu. V. Erokhin  V. A. Koroteev  V. V. Khiller  E. V. Burlakov  K. S. Ivanov  D. A. Kleimenov 《Doklady Earth Sciences》2017,477(2):1441-1444

New data on the mineral composition of Kargapole meteorite, which was found in Kurgan oblast in 1961, are presented. It has been established that the meteoritic material is represented by olivine (chrysolite), orthopyroxene (bronzite), clinopyroxene (diopside), plagioclase (oligoclase), chromite, Fe and Ni metal particles (kamacite, taenite, tetrataenite), sulfides (troilite, pentlandite), chlorapatite, and merrillite. For the first time, diopside, tetrataenite, pentlandite, chlorapatite, and merrillite were identified in the Kargapole meteorite. The chemical compositions of all minerals studied are given in Table 1. In terms of petrology, the meteorite is classified a common H4 chondrite.  相似文献   

On the UV-excesses of cepheid variables     

N. S. Nikolov  G. R. Ivanov 《Astronomische Nachrichten》1974,295(5):207-216

On the basis of the intrinsic (U – B)₀ colours of the cepheid variables, found by the authors, the UV-excesses in the maximum and minimum light δ(U – B)^max and δ(U – B)^min are defined. It is found out that the UV-excesses in the maximum light δ(U – B)^min increase with the period P (Fig. 2), but there is no correlation between δ(U – B)^min and log P. A correlation between δ(U – B)^max and the “amplitude defects” f_B is also determined. These results in connection with some other considerations, as well as the possible causes of the UV-excesses, are discussed.  相似文献   

Transverse (Sublatitudinal) Zonality of the Urals: Causes and Time of Occurrence     

Ivanov  K. S.  Puchkov  V. N. 《Doklady Earth Sciences》2022,504(2):344-348

Doklady Earth Sciences - It is shown that the observed latitudinal zonality of the Ural Fold Belt is determined mainly by the different levels of erosion of different areas. Thus, the deep levels...  相似文献