Composition and Formation Conditions of Lower Eocene Shallow-Marine Carbonates in Southern Armenia

Lithology and Mineral Resources - Nummulite facies are known to be a good indicator of Eocene shallow-water paleoenvironments. Nummulitic limestones are widespread in the Lower Eocene of...     

Paleogene of the southwestern Volgograd region (Borehole 13, Gremyach’e Area). 1. Biostratigraphy

The stratigraphy of Paleocene-Eocene rocks based on assemblages of dinocysts, benthic and planktonic foraminifers, nannoplankton, diatoms, and nummulites was refined in the sedimentary sequence penetrated by borehole (BH) 13 in the Gremyach’e potassium salt deposit. The rocks were subdivided into local lithostratigraphic units with refined ages and more substantiated reference to the general and regional scales. In addition to formations of the Volga-Caspian region: Saratov, Kamyshin, Tsaritsyn, Mechetka and Elshanka, for the Paleogene of the southwestern Volgograd region there were used formations of neighbor regions as well: Eisk Formation (Paleocene) in the eastern Donetsk Basin and the Sergeevka, Tishki and Kas’yanovka formations (Middle and Upper Eocene) in the Voronezh Anteclise. The presence of the Oligocene in the section of the Maikop Group has been established for the first time. New biostratigraphic units based on dinocysts and foraminifers were suggested.     

Microbiota and stratigraphy of lower Paleogene deposits of the Urma Plateau,Central Dagestan

The study of nannofossils, dinocysts, and foraminifera from Paleogene deposits of the Urma Plateau of Central Dagestan revealed the Paleocene-Eocene age of the Gray Formation, to apply zonations based on of all three groups of microplankton, and to correlate the regional dinocyst and planktonic foraminifer zonations to the standard nannofossil scale. Nannofossil zonation of O. Varol’s (1989) is shown to be successfully applied for subdivision of Danian deposits. The large foraminifer assemblage found in the lower Eocene deposits is correlated to the NP12-NP13 zones of the nannofossil scale.     

Middle Eocene to early Oligocene nannofossils and palynomorphs from the Landzhar section,southern Armenia: Zonal stratigraphy and paleoecology

The results of the study of nannofossils and palynomorphs from the Landzhar section in southern Armenia were used to correlate bioevents of two groups of microorganisms, recognize zonal subdivisions, and identify variations in the assemblage compositions reflecting changes in the hydrology and sedimentation regime in the basin during the middle Eocene to early Oligocene.     

Spatial distribution of low-sulfide platinum group element mineralization in the Kivakka intrusion,northern Karelia

The structure of the sulfide-bearing sequence of the Kivakka basic-ultrabasic layered intrusion of the Olanga group (northern Karelia) was investigated. The chemical and quantitative mineralogical compositions of rocks were statistically processed using factor and cluster analysis. We distinguished two sulfide levels consistently extending parallel to the strike of layering in the massif. The exact boundaries of these levels could not be defined because of the patchy distribution of sulfide minerals. The highest contents of sulfide pockets were observed near the top and base of each sulfide level. The extension of the zones with high sulfide concentrations along the strike allows us to consider them as horizons. The sulfide-bearing rocks are norites with varying mineral proportions. They may differ in the association of cumulus phases (bronzite and bronzite-plagioclase). It was shown that the specific features of the structure of the sulfide levels and horizons do not inherit the structural patterns of the silicate matrix and are not correlated with the chemical composition of rocks.