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871.
Dana Procházková Vít Kárník Ivan Brouček Reviewer A. Zátopek 《Studia Geophysica et Geodaetica》1980,24(1):102-103
an¶rt;u am mu 15- an 1979. a auu a mumuu auu. 相似文献
872.
Summary With the aid of elementary methods of the theory of dimensionality we approach the problem of existence of invariants in the process of mixing particles of a passive admixture in a field of turbulence. 相似文献
873.
Low grade hydrothermally metamorphosed mafic rocks from the Iberian Pyrite Belt are enriched in 18O relative to the oxygen isotopic ratio of fresh basalt (+6.5±1). The observed
18O whole rock values range from +0.87 to +15.71 corresponding to positive isotopic shifts of +5 to +10, thus requiring isotopic exchange with fluids under conditions of high water:rock ratios at low temperatures. The lowest
18O observed corresponds to an albitized dolerite still and is compatible with independent geochemical data suggesting lower water: rock ratios for the alteration of these rocks.The isotope data are consistent with the hypothesis that the spilites from the Pyrite Belt were produced by interaction of basaltic material with sea water.Significant leaching of transition metals from the mafic rocks during alteration coupled with available sulphur isotopic data for the sulphide ores also suggest that sea water may have played an important role in the formation of ore deposits in the Iberian Pyrite Belt. 相似文献
874.
Sea floor rhyolites from the Iberian Pyrite Belt show strong enrichment in potassium and adularia is observed to replace plagioclase. This process is in accord with thermodynamic data for the exchange reaction with ocean water which favours adularia up to about 140° C. Archaean felsic intrusives and extrusives exhibit sodium enrichment, a contrast which we attribute to lower K levels in sea water and, or, higher ocean temperatures. All of these rocks show 18O enrichment of + 6 to + 8, in compliance with low temperature sea water exchange. 相似文献
875.
Remanent coercivity spectra derived from IRM acquisition curves and thermal demagnetization of the IRM indicate that magnetite, haematite and minor amounts of goethite determine the magnetic properties of the Pliensbachian limestones at Bakonycsernye. These limestones have been sampled at approximately 7-cm intervals along a 10-m stratigraphic section which covers the whole Pliensbachian stage (Lower Jurassic) without any recognizable break in sedimentation. The primary natural remanent magnetization (NRM) is carried by detrital particles of magnetite and haematite, but it is seriously overprinted by a normal magnetization which originates from secondary haematite with a wide range of blocking temperatures. This haematite is believed to have formed diagenetically during one of the Mesozoic periods of normal polarity. However, the reversal pattern obtained after NRM thermal demagnetization at temperatures ≥450°C is thought to be characteristic of the Pliensbachian stage. 相似文献
876.
¶rt;mam mam a¶rt;u, m u a nuu mauu nu¶rt; 1970–1977. nauaumGs 11 No 131, 201 uGs 15 No 228. a¶rt; ¶rt;uam mauau ¶rt;u um. ¶rt;uu au naam nuu nu¶rt; ma. 2,uuu au ma. 3.
Paper presented at the IUGG XVII Plenary Meeting, Canberra, Dec. 1979. 相似文献
Paper presented at the IUGG XVII Plenary Meeting, Canberra, Dec. 1979. 相似文献
877.
u¶rt;m ¶rt; anum¶rt;-amm aamumu maum a aa nu mummu (). ma¶rt;am aamumu uu mau auma uu am auu a uu aaa aa. 相似文献
878.
V. B. Buryanov V. V. Gordienko N. I. Pavlenkova Reviewer I. Pšenčík 《Studia Geophysica et Geodaetica》1980,24(2):114-123
m¶rt; amamu ¶rt;uau nma nauua ¶rt; a n amu . n ¶rt;a uu u¶rt;au,aumuu u mn nma. mam maa auum ¶rt; m u nmm u¶rt;ua n¶rt;a u a maa a umua a nam . ¶rt; nmm amuu n¶rt;m uu 3,3/
3
, n¶rt; ¶rt;uuuau u na¶rt;uau mu a anma ¶rt; 3,2/
3
. ¶rt; n¶rt;uu a¶rt;u aau mum nm, maumaa ¶rt;¶rt;m aama u ¶rt; amu .
Presented at the KAPG Symposium Problems of Interpretation and Construction of Physical Models of Litosphere, Liblice (CSSR), March 6–10, 1978. 相似文献
Presented at the KAPG Symposium Problems of Interpretation and Construction of Physical Models of Litosphere, Liblice (CSSR), March 6–10, 1978. 相似文献
879.
Experimental control in the classical igneous petrology is based on determination of the equilibrium conditions of simple — mostly 1–4 component — system. The statements based on such experiments are valid for rock products chemically not influenced by active environments. For elucidation of processes between geochemically active volatile-rich country rocks, high pressure and high temperature experiments oncomplex systems containing such active rock samples, too were performed. High pressure bombs were constructed with long and narrow container, allowing to investigate the selective migration of elements between different rock samples, even by temperature slope within the container. In these bombs different igneous, sedimentary and metamorphic rocks in contact at different temperatures and pressures were investigated. P-t relations and stability fields of different mineral facies cannot be exactly determined by phase diagrams of simple uni- or multicomponent systems, because they depend on other components and on the environments, too. The new complex experiments, however permit to assess directly the stability fields of the mineral facies. The data obtained proves that an intense selective migration of the volatiles take place even in solid samples at 550° C, in some rock associations already at 250° C, if there is a concentration gradient of volatiles between the samples. Selective migration proceeds following the principle of transvaporization, i.e. towards the partial pressures — chemical activities — of the mobile components and following the sequence of their ionic potentials. In this way, different hypomagmatic and metamorphic rocks are produced. The new kind of experiments shows that — opposite to the approaches of the classical igneous petrology — a high grade contamination of the ascending magma is possible. Contamination proceeds by transvaporization. Assimilation — Einschmelzung — mostly plays an insignificant role. Gravitative crystallization differentiation operates intensely only in the higher sections of volcanic pathways, characterized by relatively low pressures and thus by low viscosity of the magma. Contamination is intense if the ascension of magma is relatively slow as it is presumable along the oblique circumpacifique or innercarpathian andesitic structural lines. In this way, basaltic magma produces andesitic to rhyolitic rocks partly abundant in volatiles. However contamination is restricted and consequently basaltic rocks are formed if magma ascends rapidly through vertical channels as it is presumably the case with the young peripherical basalt volcanics, e.g. the innercarpathian basin system. These experiments also evidence the activation process of magma by transvaporization. Selective migration of volatiles even through solid rocks is introduced by structural pressure minimum zones towards these zones, which results in the melting of neighbouring rocks and their lifting as liquid magma until volatile supply is sufficient. 相似文献
880.