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41.
I. S. Puchtel A. W. Hofmann K. Mezger A. A. Shchipansky V. S. Kulikov V. V. Kulikova 《Contributions to Mineralogy and Petrology》1996,124(3-4):273-290
In the central Vetreny Belt, southeastern Baltic Shield, an areally extensive 110 m deep lava lake is exposed consisting
of remarkably fresh differentiated komatiitic basalt. During eruption, the liquid had a temperature of 1380–1400 °C and contained
∼15% MgO. The lava ponded in a large topographic depression soon after eruption. The differentiation of the lava lake was
controlled by settling of transported olivine and chromite phenocrysts and caused the origin of prominent internal layering.
The last portions of the trapped liquid crystallized at temperatures of 1250– 1070 °C. A Sm-Nd isochron of 2410±34 Ma for
whole rock samples, olivine, augite and pigeonite separates from the lava lake provides a reliable estimate for the time of
formation of the uppermost sequences in the Vetreny Belt. This age is in good agreement with the Sm-Nd and Pb-Pb isochron
ages of 2449±35 and 2424±178 Ma for the volcanic rocks from the same stratigraphic level in the northwestern Vetreny Belt.
Modeling of Nd-isotopes and major and trace elements shows that the komatiitic basalts at Lion Hills may have had a komatiite
parent depleted in highly incompatible elements. It can be shown that this initial liquid was contaminated by 7–9% of Archaean
upper crustal material from the adjacent Vodla and Belomorian Blocks en route to the surface thus acquiring the observed geochemical and isotope signatures including relative enrichment in Zr, Ba, and
LREE, negative Nb- and Ti-anomalies and ɛNd(T) of −1.
Received: 8 December 1995/Accepted: 26 March 1996 相似文献
42.
The niobium and zirconium L III-absorption spectra in some niobates and zircons were obtained with a vacuum focusing crystal spectrometer. The effective charges of Nb and Zr in these minerals were derived from the X-ray absorption spectra. The fine structure of the absorption spectra and effective charges Nb and Zr in metamict, partly-metamict minerals and crystalline analogues made it possible to draw a conclusion as to the nature of the first coordination sphere of Nb and Zr during metamict decay and subsequent recrystallization under annealing of these minerals. 相似文献
43.
44.
The majority of original seismograms recorded at the very beginning of instrumental seismology (the early 1900s) did not survive till present. However, a number of books, bulletins, and catalogs were published including the seismogram reproductions of some, particularly interesting earthquakes. In case these reproductions contain the time and amplitude scales, they can be successfully analyzed the same way as the original records. Information about the Atushi (Kashgar) earthquake, which occurred on August 22, 1902, is very limited. We could not find any original seismograms for this earthquake, but 12 seismograms from 6 seismic stations were printed as example records in different books. These data in combination with macroseismic observations and different bulletins information published for this earthquake were used to determine the source parameters of the earthquake. The earthquake epicenter was relocated at 39.87° N and 76.42° E with the hypocenter depth of about 18 km. We could further determine magnitudes m B = 7.7 ± 0.3, M S = 7.8 ± 0.4, M W = 7.7 ± 0.3 and the focal mechanism of the earthquake with strike/dip/rake ? 260°± 20/30°± 10/90°± 10. This study confirms that the earthquake likely had a smaller magnitude than previously reported (M8.3). The focal mechanism indicates dominant thrust faulting, which is in a good agreement with presumably responsible Tuotegongbaizi-Aerpaleike northward dipping thrust fault kinematic, described in previous studies. 相似文献
45.
M.?Yu.?KhovrichevEmail author A.?A.?Apetyan E.?A.?Roshchina I.?S.?Izmailov D.?A.?Bikulova A.?P.?Ershova I.?A.?Balyaev A.?M.?Kulikova V.?V.?Petyur A.?A.?Shumilov K.?I.?Os’kina L.?A.?Maksimova 《Astronomy Letters》2018,44(2):103-118
Our goal is to find previously unknown binary systems among low-mass dwarfs in the solar neighborhood and to test the search technique. The basic ideas are to reveal the images of stars with significant ellipticities and/or asymmetries compared to the background stars on CCD frames and to subsequently determine the spatial parameters of the binary system and the magnitude difference between its components. For its realization we have developed a method based on an image shapelet decomposition. All of the comparatively faint stars with large proper motions (V >13 m , μ > 300 mas yr?1) for which the “duplicate source” flag in the Gaia DR1 catalogue is equal to one have been included in the list of objects for our study. As a result, we have selected 702 stars. To verify our results, we have performed additional observations of 65 stars from this list with the Pulkovo 1-m “Saturn” telescope (2016–2017). We have revealed a total of 138 binary candidates (nine of them from the “Saturn” telescope and SDSS data). Six program stars are known binaries. The images of the primaries of the comparatively wide pairs WDS 14519+5147, WDS 11371+6022, and WDS 15404+2500 are shown to be resolved into components; therefore, we can talk about the detection of triple systems. The angular separation ρ, position angle, and component magnitude difference Δm have been estimated for almost all of the revealed binary systems. For most stars 1.5′′ < ρ < 2.5′′, while Δm <1.5m. 相似文献
46.
Multistage deformations in the Main Ural Fault Zone is recorded in the structural features of this zone in the southern part of the Polar Urals. The deformation of the oldest metamorphic complexes in the Khord??yus massif and Dzelyayu block developed during the precollision stage. After formation of the general nappe-thrust structure of the Urals, these blocks were squeezed to the higher crustal levels. Deformation in other tectonic units started at the early collision stage during regional thrusting. Brittle failure was superposed over the all previously formed structures at the late collision and postcollision stages. 相似文献
47.
Conventional average values of Wallace-Gutzler indices for the regional circulations and average values of major variability
components of the fields of the North Atlantic surface temperature anomalies are plotted on the geographical map used to analyze
the total daily precipitation fields. The computation conditions of average values are defined by the dates classified according
to three equiprobable gradations of total precipitation. A projection of conditional average values to the precipitation field
points enables to estimate the atmospheric and oceanic “tracks” within the marked out gradations of total precipitation. The
stratification and computation of characteristics are carried out for the summer and winter seasons. Large regions are revealed
of statistically significant interrelation of the atmospheric circulation and major components of variability of the sea surface
temperature anomalies with the extreme gradations of total precipitation for summer and winter seasons. The recommendations
are formulated for the use of obtained results in the practice of the seasonal forecasting of meteorological conditions. 相似文献
48.
N. N. Kulikova A. N. Suturin E. V. Saibatalova S. M. Boiko E. N. Vodneva O. A. Timoshkin A. V. Lishtva 《Geochemistry International》2011,49(1):66-75
Based on materials collected in 2003–2007, data on aquatic lichens of the genus Verrucaria from the rocky littoral zone of Lake Baikal are discussed. The maximum density of their occurrence was observed at a depth
of 1.5 m; 95–100% of rock fragments recovered from depths of 1.5–2.2 m are encrusted by 24–43% with the thalli of Verrucaria spp. It was found that the lichens contribute actively to the physical and physicochemical weathering of their rock substrate
and prefer to reside on the rocks of granitic composition. The chemical composition of aquatic verrucaria is dominated by
the same elements that are most abundant in the rocks (Ca > K > Fe > Al > Mg > P > S > Na > Mn > Sr > Ba), and, in most cases,
the characteristic element ratios of the rock compositions are preserved in the composition of the thalli of Verrucaria spp. Compared with the elemental composition of the near-bottom water layer, the lichens most extensively concentrate the
elements that slowly migrate in water: Gd > Sm > Pr > Nd > Al > La > Dy > Tb > Y > Lu > Ce > Yb > Be > Tm > Co > Nb > Mn >
Zn. Compared with the composition of rocks, the mineral composition of the thalli of Verrucaria spp. is enriched by a factor of 100–10 in Hg > As > P > Zn > Li > S > U > Mo > Se > Cd > Ca > Tl > Sr > Pb > Be. 相似文献
49.
M.M. Buslov H. Geng A.V. Travin D. Otgonbaatar A.V. Kulikova Chen Ming G. Stijn N.N. Semakov E.S. Rubanova M.A. Abildaeva E.E. Voitishek D.A. Trofimova 《Russian Geology and Geophysics》2013,54(10):1250-1271
Packages of Late Paleozoic tectonic nappes and associated major NE-trending strike-slip faults are widely developed in the Altai–Sayan folded area. Fragments of early deformational phases are preserved within the Late Paleozoic allochthons and autochthons. Caledonian fold-nappe and strike-slip structures, as well as accompanying metamorphism and granitization in the region, are typical of the EW-trending suture-shear zone separating the composite Kazakhstan–Baikal continent and Siberia. In the Gorny Altai region, the Late Paleozoic nappes envelop the autochthon, which contains a fragment of the Vendian–Cambrian Kuznetsk–Altai island arc with accretionary wedges of the Biya–Katun’ and Kurai zones. The fold-nappe deformations within the latter zones occurred during the Late Cambrian (Salairian) and can thus be considered Salairian orogenic phases. The Salairian fold-nappe structure is stratigraphically overlain by a thick (up to 15 km) well-stratified rock unit of the Anyui–Chuya zone, which is composed of Middle Cambrian–Early Ordovician fore-arc basin rocks unconformably overlain by Ordovician–Early Devonian carbonate-terrigenous passive-margin sequences. These rocks are crosscut by intrusions and overlain by a volcanosedimentary unit of the Devonian active margin. The top of the section is marked by Famennian–Visean molasse deposits onlapping onto Devonian rocks. The molasse deposits accumulated above a major unconformity reflects a major Late Paleozoic phase of folding, which is most pronounced in deformations at the edges of the autochthon, nearby the Kaim, Charysh–Terekta, and Teletskoe–Kurai fault nappe zones. Upper Carboniferous coal-bearing molasse deposits are preserved as tectonic wedges within the Charysh–Terekta and Teletskoe–Kurai fault nappe zones.Detrital zircon ages from Middle Cambrian–Early Ordovician rocks of the Anyui–Chuya fore-arc zone indicate that they were primarily derived from Upper Neoproterozoic–Cambrian igneous rocks of the Kuznetsk–Altai island arc or, to a lesser extent, from an Ordovician–Early Devonian passive margin. A minor age population is represented by Paleoproterozoic grains, which was probably sourced from the Siberian craton. Zircons from the Late Carboniferous molasse deposits have much wider age spectra, ranging from Middle Devonian–Early Carboniferous to Late Ordovician–Early Silurian, Cambrian–Early Ordovician, Mesoproterozoic, Early–Middle Proterozoic, and early Paleoproterozoic. These ages are consistent with the ages of igneous and metamorphic rocks of the composite Kazakhstan–Baikal continent, which includes the Tuva-Mongolian island arc with accreted Gondwanan blocks, and a Caledonian suture-shear zone in the north. Our results suggest that the Altai–Sayan region is represented by a complex aggregate of units of different geodynamic affinity. On the one hand, these are continental margin rocks of western Siberia, containing only remnants of oceanic crust embedded in accretionary structures. On the other hand, they are represented by the Kazakhstan–Baikal continent composed of fragments of Gondwanan continental blocks. In the Early–Middle Paleozoic, they were separated by the Ob’–Zaisan oceanic basin, whose fragments are preserved in the Caledonian suture-shear zone. The movements during the Late Paleozoic occurred along older, reactivated structures and produced the large intracontinental Central Asian orogen, which is interpreted to be a far-field effect of the colliding East European, Siberian, and Kazakhstan–Baikal continents. 相似文献
50.
The Extreme Forecast Index (EFI) calculations are performed using the ECMWF 2-m air temperature forecasts produced in the framework of the Subseasonal to Seasonal (S2S) Prediction Project. Four computation schemes are implemented using empirical and theoretical distributions of heat wave characteristics as well as the one-dimensional test statistics of histograms and linear interpolation formulas. Case studies (for different initial dates and regions) characterized by the significant air temperature anomalies in Northern Eurasia are performed using traditional forecast skill scores and the spatial verification methods to evaluate the efficiency of the proposed schemes for different threshold values of EFI. It is shown that the forecast quality can be considered satisfactory in most cases. The dependence of forecast skill on the intensity, spatial scales, and duration of temperature anomalies is revealed. Further studies should be carried out using larger samples based on several hydrodynamic models and the multimodel approach. 相似文献