Solution of boundary value problems of the gravity potential using finite difference methods     

Jiří Nedoma  Reviewer M. Burša 《Studia Geophysica et Geodaetica》1975,19(1):85-89

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Pressure wave amplitudes in an near the shattered zone of an underground explosion measured by piezophotographic method     

Jiří Vaněk  Ludvík Waniek 《Studia Geophysica et Geodaetica》1960,4(3):290-291

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Accuracy in preparing samples of rain-water for measuring its man-made radioactivity using evaporation method     

Jiří Horák 《Studia Geophysica et Geodaetica》1960,4(2):172-183

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Amplitude curves of longitudinal waves for several three-dimensional models of the upper mantle     

Jiří Vaněk 《Studia Geophysica et Geodaetica》1966,10(3):350-359

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Formation of Colloidal Silica and Alumina During Experimental Granodiorite Weathering     

Jiří Faimon 《Aquatic Geochemistry》2003,9(4):305-341

The role of aluminum and silica in the formation of colloids during granodiorite weathering was studied on the basis of long-term experiments in batch reactors. Rock samples were dissolved in un-buffered solutions of initial pH 3.2, 5.4, and 9.9 at ambient conditions for 500 days. During weathering, extremely high supersaturation with respect to various secondary solids was attained in the solutions. Consequently, new solids, part of which was conserved in solutions as colloids, condensed. The mean concentrations of colloidal Si reached values of 70, 50, and 48 mol 1^–1 in the alkaline, neutral, and acid solutions, respectively. The mean concentrations of colloidal Al, reached values of 34, 22, and 12 mol 1^–1 in the alkaline, neutral, and acid solutions, respectively. The concentration of colloids gradually decreased after 200-400 days of experiment. This phenomenon was interpreted as being due to the competition between homogeneous nucleation and crystal growth. At the initial stages of the experiments, the colloidal species (predominantly colloidal Al) comprised a large proportion of the total amounts of aqueous species. Their share, however, decreased with time. The molar Al/Si-ratios of colloids were as high as 2–2.5 at the early stages of the experiment. After 250–300 days of experiments, on the other hand, these ratios decreased to values of about 0.5 in both the neutral and alkaline solutions and to a value of 0.15 in the acid solution. The evolution of colloids was consistent with the evolution of secondary solids in the sequence Al-hydroxides – clay minerals (illite, chlorite), in both the neutral and alkaline solutions. In acid solutions, the evolution of Al/Si-colloids was influenced by the presence of sulfate ion and Al-sulfate precipitation. Besides Al and Si, other elements, in particular Ca or Mg as a major component and Na, K, P, S, and Cl as minor components, readily participated in the formation of colloids.  相似文献   

Tectonic evolution of a continental magmatic arc from transpression in the upper crust to exhumation of mid-crustal orogenic root recorded by episodically emplaced plutons: the Central Bohemian Plutonic Complex (Bohemian Massif)     

Jiří Žák  František V. Holub  Kryštof Verner 《International Journal of Earth Sciences》2005,94(3):385-400

The Central Bohemian Plutonic Complex (CBPC) consists of episodically emplaced plutons, the internal fabrics of which recorded tectonic evolution of a continental magmatic arc. The ~354–350 Ma calc-alkaline plutons were emplaced by multiple processes into the upper-crustal Teplá-Barrandian Unit, and their magmatic fabrics recorded increments of regional transpression. Multiple fabrics of the younger, ~346 Ma Blatná pluton recorded both regional transpression and the onset of exhumation of mid-crustal orogenic root (Moldanubian Unit). Continuous exhumation-related deformation during pluton cooling resulted in the development of a wide zone of sub-solidus deformation along the SE margin of the CBPC. Finally, syn-exhumation tabular durbachitic pluton of ultrapotassic composition was emplaced atop the intrusive sequence at ~343–340 Ma, and the ultrapotassic Tábor pluton intruded after exhumation of the orogenic root (~337 Ma). We suggest that the emplacement of plutons during regional transpression in the upper crust produced thermally softened domain which then accommodated the exhumation of the mid-crustal orogenic root, and that the complex nature of the Teplá-Barrandian/Moldanubian boundary is a result of regional transpression in the upper crust, the enhancement of regional deformation in overlapping structural aureoles, the subsequent exhumation of the orogenic root domain, and post-emplacement brittle faulting.  相似文献   

Magmatic stoping as an important emplacement mechanism of Variscan plutons: evidence from roof pendants in the Central Bohemian Plutonic Complex (Bohemian Massif)   总被引：2，自引：0，他引：2  

Jiří Žák  František V. Holub  Václav Kachlík 《International Journal of Earth Sciences》2006,95(5):771-789

The presence of numerous roof pendants, stoped blocks and discordant intrusive contacts suggests that magmatic stoping was a widespread, large-scale process during the final construction of the Central Bohemian Plutonic Complex, Bohemian Massif. The measured total length of the discordant contacts that cut off the regional cleavage and were presumably formed by stoping corresponds to about half of all contacts with the upper-crustal host rocks. In addition, at least some of the straight, cleavage-parallel intrusive contacts may also have recorded complex intrusive histories ending with piecemeal stoping of thin cleavage-bounded host rock blocks into the magma chamber. Based on the above, we argue that the fast strain rates required for emplacement of large plutons of the Central Bohemian Plutonic Complex into brittle upper crustal host rocks over relatively short-time span could not have been accommodated entirely by slow ductile flow or slip along faults. Instead, the emplacement was largely accommodated by much faster thermal cracking and extensive stoping independent of regional tectonic deformation. Finally, we emphasize that magmatic stoping may significantly modify the preserved structural patterns around plutons, may operate as an important mechanism of final construction of upper-crustal plutons and thus may contribute to vertical recycling and downward transport of crustal material within the magma plumbing systems in the crust.  相似文献   

КРИТИКА     

Jiří Vaněk  D. Podhorský 《Studia Geophysica et Geodaetica》1989,33(1):107-108

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Iterative geophysical tomography     

Jiří Jech  Reviewer V. Červený 《Studia Geophysica et Geodaetica》1986,30(3):242-256

Summary The algorithm of iterative geophysical tomography is presented. The medium is approximated smoothly by means of B-splines. The tww-point problem of ray computation is solved with the aid of paraxial approximation. The parameters of the medium are obtained from the iterative algorithm of minimizing the quadratic form. Two numerical 2-D examples are given.

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u¶rt; au umamuuu mauu. ¶rt;a annuuaa n nu nu -na. ma na aa a nu nu naaua annuauu. aam ¶rt; n a umamu aua uuauauu a¶rt;amu . am nu¶rt; ¶rt;a 2-D u nua.

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Radioactivity and geochemistry of granulites and some related rocks from the saxonian granulite complex     

Jiří Fiala  Věra Vaňková  Reviewer A. Dudek 《Studia Geophysica et Geodaetica》1985,29(4):374-394

Summary The distribution of radioactive(Th, U, K), major and selected trace(Rb, Sr, Ba, Y, Zr, V, Cr, Ni) elements of granulites from the Saxonian Granulite Complex was studied. Similarly to the South Bohemian granulites, the Saxonian granulites can be divided according to the contents of their major and trace elements into two main groups, groupA containing mostly acid and subacid granulites (K ₂ O>2.5%, SiO ₂ >68%), and groupB containing mostly intermediate and basic granulites (K ₂ O<2.5%, SiO ₂ <68%). Statistically significant differences between groupsA andB were found for all major oxides and several trace elements(Rb, V, Cr, Ni). The Saxonian granulites follow the same calc-alkaline trend as the South Bohemian, granulitesA being placed mostly in the rhyolite field and granulitesB mostly in the dacite, andesite and basalt fields of this trend. The investigated granulites are characterized by a considerable scatter ofTh andU contents accompanied by very variableTh/U ratios; theTh andU concentrations of granulitesA are substantially lower than is usual for rocks of corresponding acidity.

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¶rt;a an¶rt;u a¶rt;uamu(Th, U, K) u ua ¶rt;u(Rb, Sr, Ba, Y, Zr, V, Cr, Ni) m aum n¶rt;a aaum na. naa, m u¶rt;aum n uu aam n aaum u ¶rt;u am aua, u u uu. aum n u uu ma a¶rt;um ¶rt; ¶rt;nn; nnA nua¶rt;ama a au¶rt; u au¶rt;aum (K ₂ O>2,5%, Si O ₂ >68%), nnB ¶rt;u u aum (K ₂ O<2,5%, SiO ₂ <68%). ¶rt; muunnau mm mamumuu m au ¶rt; a u u ¶rt; m ¶rt;u m(Rb, V, Cr, Ni). auaum n¶rt;¶rt;m um- m¶rt; a u -uaum;aumA a¶rt;ma a uum n, uaumB a a ¶rt;aum, a¶rt;um u aam n m m¶rt;a. ¶rt;aum — u unnA — aamum uu ¶rt;au da¶rt;uamu mTh uU.

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