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61.
Analysis of geologic reference materials for REE and HFSE by inductively coupled plasma-mass spectrometry (ICP-MS) 总被引：1，自引：0，他引：1
I. V. Nikolaeva S. V. Palesskii O. A. Koz’menko G. N. Anoshin 《Geochemistry International》2008,46(10):1016-1022
A variant of the ICP-MS technique was developed for the analysis of geological materials for REE and HFSE (Zr, Nb, Hf, and Ta) and is illustrated by analyzing geological reference materials (GRM) of various composition. The chemical preparation of the samples, including their sintering/fusing with highly purified Li metaborate and the stabilization of the solution, ensures the complete transfer of the elements to be analyzed into solution. The use of an ELEMENT high-sensitivity mass spectrometer with an U-5000AT+ ultrasonic nebulizer made it possible to improve the detection limits of REE and HFSE. A combination of an external calibration with internal standard for the calculation of the concentrations allowed us to take into account the effect of the matrix and variations in the plasma parameters on the analytical signal. The accuracy of the method is illustrated by the comparison of the results obtained on the most reliably certified GRM with the values assumed for them. The relative standard deviation of the analysis amounts to 2–5% on average, depending on the concentrations. 相似文献
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S. B. Nikolaeva A. A. Nikonov S. V. Shvarev M. V. Rodkin 《Doklady Earth Sciences》2016,469(1):656-660
This paper considers the results of detailed paleoseismic and geological investigations in a key site in the wall of the Imandra Lake depression (Kola Peninsula Region, Northeast of the Fennoscandian Shield). Study of different groups of paleoseismic deformations developed in the fault zone and the application of new methods and techniques made it possible to identify a large seismotectonic zone characterized by great earthquakes at the end of the Late Glacial and in the Holocene. The investigation data are indicative of the necessity to estimate the seismic potential in the Kola Atomic plant area in a different way. 相似文献
63.
Analysis of materials on the geological structure and tectonics of the White Sea depression area suggests that this depression existed in the Middle Pleistocene and was connected with the World Ocean. It is still impossible to determine the exact time of its formation due to an insufficient knowledge of the depression loose cover. However it is most likely that the depression was formed in the Late Miocene and Early Pliocene, when after the regressive development of the continental margin the shelf subsidence began. Probably in the Holocene the divergent regime was replaced by the transform regime. This period saw the subsidence of the Kandalaksha graben to about 150 m and the formation of the Kolvitsa graben. The crystalline rocks surrounding Kandalaksha bay were involved in the subsidence which is reflected in the isobase curve of the glacioisostatic uplift of the area. The combined impact of the tectonic component and the glacioisostatic uplift led to a rise of tensions which discharge caused a high seismic activity of the Kandalaksha graben and its environs. 相似文献
64.
Heavy mineral associations from tephra layers in the Quaternary deposits of the Sea of Okhotsk and their chemical characteristics were studied by various techniques. It was shown that such investigations may have a bearing on the problems of tephrostratigraphic correlation. We assessed the possibility of application of the mineral composition of distal tephra for identification and, in particular, estimation of the relation of tephras to the explosive volcanism of back-arc and frontal zones of island arcs. The investigation of the compositions of minerals and use of mineral geothermometers and geobarometers (two-pyroxene, magnetite–ilmenite, and amphibole) provided evidence on the physicochemical parameters of melt crystallization during the explosive volcanic eruptions that produced the distal tephra layers. It was established that the pyroclastic material of some tephra layers was supplied during explosive eruptions not only from shallow magma chambers but also from deeper and higher temperature reservoirs. Together with the geochemical signatures of volcanic glasses, the obtained results on mineral associations and the geochemistry of mineral inclusions are applicable for the comparative analysis and correlation of tephras from marine and continental sequences, as well as for the identification of explosive volcanic products in adjacent land areas. 相似文献
65.
Measurement of the floor in the interplanetary magnetic field and estimation of the time-invariant open magnetic flux of the
Sun require knowledge of closed magnetic flux carried away by coronal mass ejections (CMEs). In contrast with previous papers,
we do not use global solar parameters to estimate such values: instead we identify different large-scale types of solar wind
for the 1976 – 2000 interval to obtain the fraction of interplanetary CMEs (ICMEs). By calculating the magnitude of the interplanetary
magnetic field B averaged over two Carrington rotations, the floor of the magnetic field can be estimated from the B value at a solar cycle minimum when the number of ICMEs is minimal. We find a value of 4.65±0.6 nT, in good agreement with
previous results. 相似文献
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67.
S. V. Bushnev E. V. Myasnikov N. B. Nikolaeva A. A. Romanov 《Physical Oceanography》1994,5(4):287-293
Methods of rapid analysis of the chlorophyll-a concentration vertical profile by the spectra of incident solar radiation are suggested. The methods are applicable for the ocean layerz=20–80 m containing waters of type 1 (by Morel's classification). Testing of the methods underin situ conditions showed that they can be used to reconstructC
ch(z) profiles, with a relative error of 10% and a root-meansquare error of 20–30% at most, provided the data are calibrated using field observations conducted at two or three sites in the test area.Translated by Vladimir A. Puchkin. 相似文献
68.
The coefficients of synchrotron emission and absorption and of Compton extinction in a gas of ultrarelativistic electrons
containing a random magnetic field are represented by rapidly converging power series for a power- law distribution of electron
energy having any exponent. Exact and approximate expressions are given for the frequency redistribution function. The results
will be used to calculate the emission from jets of active galactic nuclei.
Translated from Astrofizika, Vol. 41, No. 2. pp. 197–216, April-June, 1998. 相似文献
69.
We investigate crustal growth processes on the basis of a 2D coupled geochemical—petrological-thermomechanical numerical model
of retreating intraoceanic subduction. The model includes spontaneous slab retreat and bending, subducted crust dehydration,
aqueous fluid transport, mantle wedge melting, and melt extraction resulting in crustal growth. Our numerical experiments
show that (1) the rate of plate retreat influences both the rate of crust formation and composition of newly formed crust;
(2) both the intensity of melt extraction and the age of subducted plate affect the volume of newly formed crust. In the present
paper we describe possible scenarios of magmatic and geodynamic evolution of the arc system and then compare results with
magmatic addition rates of Western Pacific arcs.
Published in Russian in Vestnik Moskovskogo Universiteta. Geologiya, 2009, No. 4, pp. 30–43.
The text was submitted by the authors in English. 相似文献
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