Suchergebnisse

Models of copper-porphyry deposits formation examined from the petrological and geochemical points of view. The principal differences between the models are time and mechanism of sulfide ore precipitation and the composition of ore-bearing fluid. It is shown that copper-rich fluid inclusions contain insufficient amount of sulfur for sulfide ore formation and it have to be independent source of sulfur for copper-porphyry deposits formation.

We present first data on the composition of melt inclusions in plagioclase and quartz crustal clasts and detailed study of plagioclase chemical zoning and mineral compositions from Bakhchysarai Late Albian tuffites. All magmatic melt compositions fall into field of high-K rhyolites. Measured water content in melt inclusions is up to 4 wt.%. Phenocrysts crystallized at the temperature within range 820-860 °C and pressure not less than 1 kbar. Bakhchysarai tuffites were formed in active continental margin geotectonical settings.

Zoned crystals record changes in magma evolution, such as injection of mafic magma into a shallow magma chamber, which often triggered to eruption of arc volcanoes. We applied diffusion chronometry for reverse zoned crystals of orthopyroxene from 6 eruptions of Bezymianny volcano during 2006–2012 years and showed correlation between time of injection of new magma and recorded seismicity. We descripted two type of Bezymianny volcano eruptions, which driven by different trigger mechanisms: 1) orthopyroxene rims formed during up to 3 years previous to eruption; 2) orthopyroxene rims formed during 0–2 months previous to eruption.

At least two outcrops of igneous rocks have been reported from the watershed of the Bodrak and Alma rivers (south-western Crimea). Previous studies suggested that these are intermediate to acidic volcanic rocks of pre-Middle Jurassic age. We compared the rocks from one of these outcrops with those from the near-contact area of the Middle Jurassic Dzhidairskiy intrusion, which is located proximally and predominantly consists of mainly of altered dolerites. It was determined found that the rocks from both locations were significantly altered as a result of the processes of acid metasomatism, down to quartz-carbonate-dikkite metasomatites. In this case, the nature of the changes and the appearance features of relatively unaffected by this metasomatism samples the most unaltered samples represented by altered dolerites are of the same type in both locations.