Amphibolites from the Vertiskos and Kerdyllia series of the Serbo-Macedoninn massif, Northern Greece, are examined in terms of their mineralogy and petrochemistry. Evidence based on data derived from the geochemistry and mineral parageneses, indicate that the rocks in study arc of basic igneous origin and have metamorphosed in the amphiboli tefacies. The nature of the parental magma, as deduced from the normative compositions and chemical variation trends is in general of tholeiitic compositi on. Discrimination diagrams based on major and trace elements suggest a possible ocean-floor tectonic affinity.
No abstract is available for this article.
Ortho- and paraamphibolites in the northern part of the Central Rhodope Mts. are metamorphosed into amphibolite facies showing no traces of migmatization. This study is an analysis of the major and trace elements, REE included. Part of the orthoamphibolites represented by amphibolized metabasalts and garnet amphibolites are products of a subvolcanic autochthonous magmatism of tholeiitic affinities. Geochemically, they are comparable to the island-arc igneous rocks. The mrtabasalts show high alumina contents, varying iron and titanium contents and a tholeiite-like REE distribution. The garnet amphibolites are characterized by high iron and titanium contents. The predominating role of garnet in these rocks is reflected in the marked prevalence of HREE among REE and in the negative europium anomaly. Some bedded amphibolites of unknown origin show similar geochemical characteristics combining the features of island-arc and of ocean-floor tholeiites. The paraamphibolites differ sharply from the typical orthoamphibolites in their much lower iron, titanium and vanadium contents and higher calcium, aluminium, zirconium and LREE contents. Fe, Ti, Mg. V, Cr, Ni, Zr, Hf and REE are relatively immobile elements during metamorphism and their ratios can be reliably used to distinguish, characterize and determine the primary features of the amphibolite rock groups.
No abstract is available for this article.
The reconstruction of the stress fields in Northeast Bulgaria by means of tectonic fracture patterns and physical anisotropy of rock species from the Lower Cretaceous period up to the Upper Pliocene shows that in the investigated area exists a stable trend towards a clockwise rotati on of the maximum and minimum compress ion axes. They are subhorizontal, the compression after the Lower Cretaceous period being in NE-SW direction, while after the Pliocene the compression is already in NW-SE direction. According to the mechanisms of seismic foci in the regi on this direction has been preserved till now. Rotation either of tectonic stress fields in aclockwise manner or the more probable counter-clockwise rotation of this block of the Moezian plate has been suggested.
No abstract is available for this article.
Metasomatic facies in the zones of acid leaching of the Spahievo ore field are defined in terms of the theory of metasomatic zonality by paragenetic analyses of each zone. The integral metasomatic column derived identifies the metasomatites as belonging to the secondary quartzite formation. The propylitic type of rocks forming aureoles around the secondary quartzites proper do not belong to the propylite formation but are the outer zones of the secondary quartzite forrnation.
The physico-chemical analysis of mineral parageneses in the secondary quartzites proper determines the equilibria of coexisting quartz, alunite, diaspore, dickite and sericite and of coexisting quartz, alunite, diaspore sericite and pyrophyl!ite as dependent on two of the intensive parameters, namely the chemical potentials of K+ and SO4-2 and pH of the mineral-forming environment.
The physico-chemical conditions of formation of secondary quartzites in the Spahievo ore field are characterized using experimental and thermodynamic data reported in the literature.
Coal and coal argillites from seams I, II and III and from coal intercalations above the latter have been sampled and chemically analyzed. The contents of 28 elements detected in the coal ash and 29 in the coal argillites have been determined. The mean values of element contents in the coal ash are compared with the clarke of concentration for bituminous coal and groups of elements typomorphic of each seam were defined. Typomorphic elemens are also defined for the coal argillites of each seam by comparing the mean contents with the clarkes of concentrat ion for sedimentary rocks. The ratio bet ween the mean element contents in the coal ash and in the ash of coal argillites is used to determine the affinity of elements to organic matter. Elements bound to the organic matter are found to predominate in seams I and II whereas seam III is dominated by inorganically bound elements. Each seam is characterized by a specific distribution of the elements among the five groups defined on the basis of their affinity to organic matter. Correlation coefficients between the elements have been derived by computer processing of data. They are used to define five geochemical assemblages for each seam plotted on graphs to show the e1emenl interdependence. Both the graphs and the assemblage compositi ons show differences in each seam.
No abstract is available for this article.
S. Boyadzhiev. Formalized geochemical models have been constructed in the relative metrics of a standard in the primary halo contour of the main component. They arc based on geochemical zonality studi esand on the similarity method. Formalized models of gold and polymetallic ore formations were built for the first time in Bulgaria on the example of the copper-gold-polymetallic deposits in Vozdol in the Chelopech ore field. For that purpose were used investigations on the relationships belween the alterations in gold productivity and on the total amount of lead and zinc and the changes in the ore zones in depth. Taking into account the models the range of two types of ore depos its as well as the prognostication of metal resources according to geochemical data were determined. The prospects of gold and lead-zinc formation in an ore deposit were specified. A model of the gold formation for the whole field of the ore deposit was created according to the for ecast resources assessment. The numeriacal values of the factor for the estimation of the prognostication resources of gold in genetically similar deposits differing in sizes were found. The obtained models confirmed the well-known generalization of the endogenous ore formation. They can be used further for the estimation of similar sites in the ore field of Panagjurishte. On the example of the lead-zinc deposits in Rouen and Mali Rouen from the Ossogovo ore region, as well as the copper-pyrites deposits Radka in Panagjurishte ore region, it has been demonstrated how the real extent of the standard can be enlar ged and how the necessary number of zone indices may be chosen so that the formalized models of endogenous ore formation are constructed more effectively. This method is suitable for the creati on of the formalized models of the main industrial types of hydrothermal ore deposits in Bulgaria on the basis of the available data.
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