Entity

Time filter

Source Type


Based on an analysis of the significant collections of Favositidae (tabulate corals) from the Upper Ordovician-Lower Devonian of the Taimyr Peninsula, Western Slope of the North Urals and the Tchernychev Uplift, this paper focuses on the macro- and micro-structurye{cyrillic} of the corallite wall. Seven structural types of the corallite wall have been recognized; some of them seem to have a definite stratigraphic range. The results contribute to the long-time discussion on the applicability of skeletal structure for systematics of the Favositidae, its evolutionary implications, and stratigraphic correlation. It has been held that the skeletal structure of the fossilized remains of Favositidae is inapplicable for such purposes because diagenetically, it is secondary, being a product of mineral replacement of the primary structure. In contrast, an assumption is made here that the " secondary" skeletal macro- and micro-structure may reflect in some way the " primary" skeleton. As a result, it is proposed that some evidence of evolution of the Favositidae may be obtained by evaluating the stratigraphic range of favositid representatives possessing different types of structure of the corallite wall. © 2010 Elsevier Ltd and Nanjing Institute of Geology and Palaeontology, CAS. Source


Shatov V.V.,All Russian Geological Research Institute VSEGEI | Moon C.J.,Rose Cottage | Moon C.J.,University of Exeter | Seltmann R.,Natural History Museum in London
Journal of Geochemical Exploration | Year: 2014

Rock geochemical surveys have been widely used for mineral exploration in Russia and more generally, the former Soviet Union. Some conducted by VSEGEI have in addition to geochemistry, determined quantitative petrography on the survey samples.In the case described, a regional survey in the Yubileinoe area southern Urals of Kazakhstan has been undertaken to investigate a district which has both the characteristics of volcanic associated massive sulphide and porphyry style mineralisation. Samples were collected on a 500. m or tighter grid over a 10. ×. 10. km area and analysed by direct current arc spectrometry as well as quantitative mineral determination on thin sections. The combination of these techniques was used to determine elemental loss and gain relative to host rocks in addition to alteration facies. GIS techniques were also used to investigate the spatial variation of geochemical and mineral primary concentrations.Although the porphyry deposit at Yubileinoe gives a clear signature, software based discrimination of alteration into VMS and porphyry types allows better targeting for follow-up. The porphyry signature is detectable for approximately 350. m into wallrock in mono-element data, notably Cu and Au. Multiplicative haloes are of similar magnitude although less noisy. This approach also allows the mapping of alteration facies and combination into loss and gain maps as well as a prognostic map of mineral deposit potential.The use of manual quantitative mineralogy is prohibitively expensive where labour is costly. However the advent of computer-based methods means that this approach may well be viable in the future. © 2014 Elsevier B.V. Source


Bugrova I.Y.,Saint Petersburg State University | Bugrova E.M.,All Russian Geological Research Institute VSEGEI
Stratigraphy and Geological Correlation | Year: 2015

This work summarizes updated data on Paleocene and Lower Eocene deposits of the Crimean Peninsula concerning the systematics of assemblages of small foraminifers (and partly data on other microfossils) and results of biostratigraphic subdivision of sections. It is shown that Lower Paleocene and Lower–Middle Eocene deposits accumulated during two cycles of carbonate sedimentation in a warm-water shallow basin. These deposits are separated by Upper Paleocene deep-water deposits. The systematic composition of foraminifers testifies that there were different facies conditions in different parts of the Crimean basin and its connection to Western European and Tethyan basins during the Paleocene–early Eocene. © 2015, Pleiades Publishing, Ltd. Source


Vozarova A.,Comenius University | Smelko M.,Comenius University | Paderin I.,All Russian Geological Research Institute VSEGEI | Larionov A.,All Russian Geological Research Institute VSEGEI
Geologica Carpathica | Year: 2012

U-Pb dating (SHRIMP) of magmatic zircon ages from the Northern Gemericum Permian volcanics (Petrová Hora Formation) yielded the Concordia age of 272.4 ± 7.3 Ma for basaltic andesite, as well as the Concordia age of 275.2 ± 4 Ma for rhyodacites. Both zircon ages correspond to the Cisuralian Epoch in the time span of the Kungurian Stage. Acquired 206Pb/238U zircon age data support the nearly contemporaneous origin of the acid and basic volcanogenic members in the Northern Gemericum Permian strata. The bimodal volcanic suite proves the transtension/extension tectonic regime in the North Gemeric sedimentary basin during the Late Cisuralian. The magmatic zircon ages of rhyodacites, occurring in the lower thrust sheet of the Bôrka Nappe (Jasov Formation), gave a younger Concordia age of 266 ± 1.8 Ma proving the Guadalupian Epoch, in the time span of the Wordian/Capitanian. In comparison to the Northern Gemericum realm, this age refers to the relatively younger stage of rift-related extensional movements. In the wide Alpine-Dinarides realm the Middle Permian (Guadalupian) movements are related to the beginning of the Alpine sedimentary cycle. Thus, the Middle Permian rifting expresses the beginning of the formation of the future Meliata oceanic trough. Source


Bugrova E.M.,All Russian Geological Research Institute VSEGEI | Starshinin D.A.,All Russian Geological Research Institute VSEGEI
Stratigraphy and Geological Correlation | Year: 2013

In Northeastern Tajikistan (Peter I Ridge), we have studied the foraminifer complex in the sulfatecarbonate deposits of the Shikerga Member, previously regarded as Jurassic. According to the data obtained, the age of the Shikerga Member is considered to be Paleocene. An analysis of the faunal remnants and rock composition makes it possible to suggest that an intracontinental basin existed in the studied area in the Paleocene. Sometimes, waters of the Tethys Ocean, settled by planktonic and thermophilic benthic foraminifera, penetrated into the Tajik Depression. © 2013 Pleiades Publishing, Ltd. Source

Discover hidden collaborations