The lokhkovian deposits of the Pechora-Kolva aulacogen. (stratigraphy, correlation)

The paper contains a short observation of the Lower Devonian deposits study of the Pechora-Kolva aulacogen. The Kolva and Pechora-Kozhva megaswells, the Denisov depression represent the aulacogen in the contemporary tectonic plan. Facial diversity, thickness variations are typical of the Lokhkovian deposits of the Pechora-Kolva aulacogen. The thikness of deposits varies from 1509 meters to the pinching out in the paleouplifts. In the sections of the Kolva and Pechora- Kozhva megaswells the Lokhkovian transgressive-regressive cycles are represented by open shelf facies with rich faunal assemblages (Ovinparma horizon) and by lagoon facies with a poor complex of fauna (Sotchemkyrta horizon). In the Denisov depression the Lokhkovian terrigenous sediments are developed. The stratigraphic schemes with facies types and zones of their development are shown. For the stratigraphic schemes the lithology characteristics and diagrams of geophysical log characteristics (electric log, gammaray log, borehole gauging) were used.The geophysical and lithological datum determined in the reference section of the Timan-North Urals region were used for recognition of the synchronous units in the Pechora-Kolva aulacogen sections. The formation of the transgressive-regressive sedimentary cycles are interrupted by events which are the basic event marks: Pridoli-Lochkov, early-late Ovinparma, late Ovinparma-Sotchem- kyrta. The ostracodes fauna in view of their multiplicity and euryfaciality ap- peared to be most useful for the correlation. The ostracode biozone succession in the Pridoli-Lochkov interval was developed. The biostratigraphyc ostracode subdivigions correspond to sedimentary macrocycles: Kloedenellitina margaritae - Parabairdiacypris ovatus, Orthocypris dissidentius - Sulcocavellina ovinparmica, Welleriella ventriumbonata. The ostracode complexes correspond to the frame- work of lithological and geophysical correlation datum. On the basis of lithologi- cal, geophysical and biostratigraphical data the lateral change of Lochkovian deposits of the Pechora-Kolva aulacogen was traced. The similitude of transgres- sive-regressive cycles composition of the Varandey-Adzva structural zone and the aulacogen was established.