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E.V. Lazareva S.M. Zhmodik A.V. Prokopiev N.S. Karmanov A.I. Sergeenko 《Russian Geology and Geophysics》2018,59(10):1330-1347
Nodular monazite occurs in metamorphic rocks worldwide and has zonal REE patterns. This paper focuses on the composition of nodular monazite hosted by Permian black shales of the Kular Ridge in the Kular-Nera terrane. This monazite variety (called kularite in the Russian literature) reaches commercial amounts in placers of the area. The contents of Ce, Nd, and La in the analyzed monazite nodules show correlations at Ce/Nd = 14.39La + 0.0919 (in apfu) and Ce/Nd = 0.2318La + 0.1135 (in wt.%) and vary regularly from core to rim. All monazite compositions fall on this trend, but specific grains may plot in its different parts. Thermodynamic calculations indicate that monazite forms via an intermediate precursor (LnPO4·2H2O). The Ce:La:Nd changes in different grains record Eh-pH variations during nucleation and a gradual temperature increase during subsequent growth. The Ce:La:Nd ratio changes partly in grain rims as a result of oxidative dissolution. Judging by the tectonic setting, REE came to the Kular-Nera rocks from the weathered Tomtor Nb-REE deposit, being transported by the Paleo-Khatanga River with monazite nanoparticles bound to the surface of clay minerals. 相似文献
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The statistics of the relative variations (δfoF2) in the critical frequency of the ionospheric F 2 region during catastrophic earthquakes with magnitude M ≥ 6 at 70 vertical sounding (VS) automatic ionospheric stations (AISs) of the global network is considered. Five-day periods including 70 such situations have been selected for 1981 and 1983–1985. Five sets of 24 foF2 measurements from 3 days before to a day after the earthquake instant are formed for each AIS. The number of AISs, for which the fourth statistical invariant is above the significance level (E ≥ 1), has been analyzed. It has been indicated that the histogram deformation at the set of AISs is substantial a day before earthquakes. 相似文献
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Geomagnetism and Aeronomy - The features of a time series of variations in the critical frequencies of the ionospheric F2 layer have been studied out based on a large file of experimental data. The... 相似文献
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Yu. K. Kalinin N. P. Sergeenko A. L. Dzvonkovskaya V. A. Kuznetsov T. D. Platonov V. V. Velichko 《Geomagnetism and Aeronomy》2010,50(1):64-68
Relative variations in the critical frequency of the ionospheric F, region are considered as one of the main sources of information about the characteristics of plasma inhomogeneities in the region of the main ionization maximum and as a substantial factor responsible for the statistics of the decameter signal parameters on radio paths with different lengths. The functions defined on finite intervals are also used in statistical modeling in addition to the available methods. Such a consideration made it possible to remove a restriction, peculiar to previous models, in the form of the requirement that the fourth statistical invariant—excess— should be positive. This makes the generalized statistical model more universal, which is of special importance for high4atitude radio paths. The specified mo del more adequately corresponds to the experimental data, which are characterized by finite intervals where the quantities are measured. 相似文献
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The daily samples of the hourly measurements of the foF2 critical frequency, obtained on January 5–21, 1995, at the midlatitude and high-latitude automated ionospheric stations (geographic latitude higher than 60°), are considered. The {fo} sets are transformed into the {δfoF2} sets of relative variations, for which asymmetry (A) and excess (E) are calculated. The selected stations are grouped into 20 pairs of automated ionospheric stations (AISs) located at distances of 200–10 000 km from one another. Sign estimates of the cross-correlation coefficients between the sets of 16 A and E values for different pairs of stations are used. Two types of structures of the statistical invariant spatial distribution are established: the structures with a scale of about 300 km, invariant with respect to latitude, and with a scale of about 6000 km (for only high latitudes). 相似文献
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Geomagnetism and Aeronomy - The features of interannual (1948–2015) time series of variations of critical frequencies of the F2 layer during disturbances are studied based on the large array... 相似文献
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