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151.
A.?Galli B.?Le?Bayon M.?W.?SchmidtEmail author J.-P.?Burg E.?Reusser S.?A.?Sergeev A.?Larionov 《Contributions to Mineralogy and Petrology》2012,163(2):353-378
Permian granulites associated with noritic intrusions and websterites are a common feature of the post-Variscan European crust.
Such granulites are common in the Southern Alps (e.g. Ivrea Zone), but occur only in the Gruf Complex in the Central Alps.
To understand the geotectonic significance of these granulites, in particular in the context of Alpine migmatisation, zircons
from 15 high-grade samples have been U–Pb dated by SHRIMP II analysis. Oscillatory zoned zircons from charnockite sheets,
interpreted as melts generated through granulite facies fluid-absent biotite melting at 920–940°C, yield ages of 282–260 Ma.
Some of these zircons contain inclusions of opx, unequivocally attributable to the granulite facies, thus confirming a Permian
age for the charnockites and associated granulites. Two samples from an enclave-rich orthogneiss sheet yield Cambrian and
Ordovician zircon cores. Two deformed leucogranites and six ortho- and augengneisses, which compose two-thirds of the Gruf
Complex, give zircon ages of 290–260 Ma. Most zircons have milky rims with ages of 34–29 Ma. These rims date the Alpine amphibolite
facies migmatisation, an interpretation confirmed by directly dating a leucosome pocket from upper amphibolite facies metapelites.
The Gruf charnockites associated with metre-scale schlieren and boudins of opx–sapphirine–garnet–granulites, websterites and
gabbronorites can thus be identified as part of the post-Variscan European lower crust. A geotectonic reconstruction reveals
that this piece of lower crust stranded in the (European) North upon rifting of the Neotethys, such contrasting the widespread
granulite units in the Southern Alps. Emplacement of the Gruf lower crust into its present-day position occurred during migmatisation
and formation of the Bergell Pluton in the aftermath of the breakoff of the European slab. 相似文献
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S. G. Sergeev S. A. Klimanov N. N. Okhmat G. A. Sivtsov 《Bulletin of the Crimean Astrophysical Observatory》2010,106(1):92-98
The AZT-8 70-cm telescope of the Crimean Astrophysical Observatory was upgraded in the early 2000s. Obsolete pieces of equipment
of the telescope were replaced and new ones were developed. The creation of a special control program has enabled the telescope
to be pointed at objects automatically. As a result, it has become much easier to control the telescope and the efficiency
of using the observing time has increased significantly. 相似文献
155.
Tishchenko P. Ya. Lobanov V. B. Tishchenko P. P. Semkin P. Yu. Sergeev A. F. Anisimova E. V. Barabanshchikov Yu. A. Melnikov V. V. Ryumina A. A. Sagalaev S. G. Ulanova O. A. Shvetsova M. G. Shkirnikova E. M. 《Oceanology》2022,62(1):80-92
Oceanology - The hydrological and hydrochemical data of surface and bottom waters of Academy Bay were obtained on two POI FEB RAS cruises carried out from July 11 to 14, 2016 and from September 15... 相似文献
156.
We analyze the spectroscopic and photometric observations of the active galactic nucleus (AGN) 1E 0754.6+3928 performed at Crimean Astrophysical Observatory in 1998–2004. Based on formal spectroscopic criteria for the optical wavelength range, we can classify this object as a narrow-line Seyfert 1 (NLS1) galaxy. Over the period of its observations, the AGN 1E 0754.6+3928 showed a very low rms flux variability amplitude in both continuum and Hβ (~3%). The Hβ time lag relative to the continuum has been found from the cross-correlation function centroid to be τ cent = 112 ?67 +215 days. This result and the Hβ line dispersion estimate have allowed us to determine the central black hole mass by the reverberation method: 1.05 × 108 M ⊙. The position of 1E 0754.6+3928 in the black hole mass-luminosity diagram agrees with the positions of other NLS1 galaxies and can be explained by an enhanced mass accretion rate in the central source. 相似文献
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