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391.
Marta Krsová Miroslav Krs Petr Pruner Richard Chvojka Reviewer V. Kropáček 《Studia Geophysica et Geodaetica》1989,33(4):338-361
Summary Porcellanites and palaeo-slags from North Bohemia are natural materials which can be used to derive the palaeomagnetic directions and palaeointensity of the geomagnetic field active at the time of caustic alteration. The origin of these rocks, called erdbrands, was due to the caustic alteration of predominantly pelitic sediments as a result of underground fires conditioned by spontaneous ignition of coal seams. The caustic alteration occurred during the Upper Pliocene to the Quaternary. Three procedure based on the methods by Thellier and Nagata are presented in the paper. The newly developed apparatus MAVACS (Magnetic Vacuum Control System) was used for the thermal demagnetization of samples. A procedure based on multi-component analysis was also proposed and tested. Besides some methodic results, it was found that the geomagnetic field intensity varied during the respective period within the limits of 48%±4% to 154%±32% of the present geomagnetic field intensity.
aum u na au a mumuu uu n¶rt;mam nu¶rt; amua, m n¶rt;¶rt;um ¶rt; ¶rt;u naaum anau u naumumuaum n, ¶rt;m amu uu. mu n¶rt;, aa ¶rt;a¶rt;, uu n¶rt; uu amu uu num num a¶rt; n¶rt; ¶rt;mu aau . amu uu u m nu¶rt; m nua ¶rt; mmu nu¶rt;a. am n¶rt; mu umnmau nua, n¶rt;¶rt;u ¶rt; ¶rt;u naumumu, nuau a m¶rt; u aama. a aamaa annaama MAVACS (Magnetic Vacuum Control System) a unaa ¶rt; mu aauuau ¶rt; amu aa. n¶rt; u n n¶rt;¶rt;, a a munm aau amuauu. nu m¶rt;uu au, ma ma, m umumaum n u¶rt; nu¶rt; a n¶rt;a 48%±4%-154%±32% au umumu aum n.相似文献
392.
Summary Localization errors made by approximating a given medium by a homogeneous rectangular block model and due to the approximative solution of two-point ray tracing are estimated for four different structures. The separate influence of the individual characteristics of the medium is discussed. The iterative Geiger method supplemented by a generalized inversion of the damped least-squares and Marquardt algorithm is used for localizating five hypothetical hypocentres using 9 stations. Travel times in the original structures, used as input data for localization, are calculated using a special ray tracing system.
am uu auauu a annuau a ¶rt; ¶rt; ma u ma ¶rt;¶rt; u annuau m a ¶rt; munau nuuum .相似文献
393.
Jan Kozák Tomáš Lokajíček Jan Šílený Reviewer K. Pěč 《Studia Geophysica et Geodaetica》1983,27(2):133-142
nua ¶rt;u a¶rt;am m aa ¶rt;uaaa . ¶rt;u aam ¶rt; ¶rt; uu umuo au uu m a u a u am mu ma. mu anmau mu ma n¶rt; auumu m a aa u anau nu au. num ma uu nu un u n mu ma n¶rt;mauu n¶rt;um uu m umua. mam ¶rt;umum mu u aua n au muna ma a umua uu un. ¶rt; aauua am na mu ma, m uam ua u. 相似文献
394.
395.
Summary A continuous, but attenuated section through orogenic lower and middle crust overthrust by a second lower-crustal complex
was distinguished at the eastern margin of the Bohemian Massif. This indicates the existence of two lower-crustal “autochthonous”
extrusions into middle crust that is not compatible with the model of “allochthonous” lower crustal klippen remaining after
flat thrusting of the Gf?hl nappe over large distances. The base of the lower crust is represented by a granulite body exhumed
from c. 15 kbar and 800 °C. A hangingwall complex of layered amphibolites gradually passes into amphibolite bearing paragneisses
(the Monotonous unit) and micaschists intercalated with marbles at the top (the Varied unit). The metamorphic grade and anatexis
decreases upwards and the micaschists preserve a prograde path to c. 8 kbar and 700 °C. This sequence is overthrust by a second
lower crustal strongly migmatitized complex, referred to as the Raabs complex, which is marked by an eclogite-bearing belt
at the base. The garnet zoning of eclogite indicates burial from 10 kbar to min. 15 kbar. In all units, relics of a steep
metamorphic fabric were identified, reworked by folding and a moderately west-dipping foliation. The conditions of 7–10 kbar
and approximately 750 °C for the flat foliation were obtained in all units indicating that exhumation of the lower crust into
a middle crustal level occurred earlier, probably during the development of steep fabrics. The intense flat fabric is interpreted
as a result of thrusting of the whole assembly over the middle crustal Brunian indentor. 相似文献
396.
M. Burša S. Kenyon J. Kouba Z. Šíma V. Vatrt V. Vítek M. Vojtíšková 《Studia Geophysica et Geodaetica》2006,50(4):509-524
The long-term variations in the second degree sectorial Stokes parameters of the geopotential have been determined from TOPEX-POSEIDON
(T/P) satellite altimeter data, covering the period of January 1, 1993 to January 3, 2001 (T/P cycles 11-305). It is the first
attempt to determine the variations in the second sectorial harmonics in the Earth’s inertia tensor due to the ocean dynamics.
The variations amount to about 1 × 10−10 (J
2
(2)
≈ 1.6 × 10−6 and S
2
(2)
≈ −0.9 × 10−6). The variations are about 5% of the tidal effect. This corresponds to variations in the directions of the equatorial axes
of the Earth’s inertia ellipsoid of up to 10 arc-seconds. Consequently, the annual and semi-annual variations of the Earth’s
equatorial flattening is about 10−9; i.e. it corresponds to a change of 8 units of its denominator of 91 030. (The equatorial flattening ≈ 1/91 030).
Since the coverage of the Earth’s ocean surface is not worldwide, and the inclination of T/P is i = 66°, it is only 58.2%
(min. depth of the ocean 2 000 m) of the Earth’s surface which is processed, the torque, resulting from the seasonal transfer
of masses within a sea surface layer, is not zero. It amounts up to 1016 kg m2s−2, which is comparable to the total indirect tidal torque due to the Moon and the Sun, ∼ 3.9 × 1016 kg m2s−2. However, the above estimate strongly depends on the adopted thickness of the sea surface layer, ΔR = 50 m. For a larger
thickness of ΔR = 100 m, the seasonal torque amounts to about ∼ 2.3 × 1016 kg m2s−2. 相似文献
397.
398.
399.
400.
Agakhanov A. A. Stepanenko D. A. Zubkova N. V. Pautov L. A. Pekov I. V. Kasatkin A. V. Karpenko V. Yu. Agakhanova V. A. Škoda R. Britvin S. N. Pushcharovsky D. Yu. 《Geology of Ore Deposits》2021,63(7):654-667
Geology of Ore Deposits - Abstract—This paper describes the first Na-dominant member of the beryl group, named avdeevite. The sample, which became its holotype, was found in a granitic... 相似文献