THE RUSSIAN PLATFORM AS A KEY REGION FOR VOLGIAN/TITHONIAN CORRELATION: A REVIEW OF THE MEDITERRANEAN FAUNAL ELEMENTS AND AMMONITE BIOSTRATIGRAPHY OF THE VOLGIAN STAGE

A review of the ammonite faunas and biostratigraphy of the uppermost Kimmeridgian - lowermost Middle Volgian of Central Russia is presented. The major role of the Sub-mediterranean ammonites in the Volgian assemblages is described, providing additional detail to the existing scheme of Tithonian-Volgian correlations. The base of the Tithonian and the base of the Volgian are coincident, based on the association of Neochetoceras steraspis-Lingulaticeras solenoides. The Klimovi Zone corresponds to most of the Hybonotum Zone. However, the top of the Hybonotum Zone, based on the distribution of Paralingulaticeras, falls within the Sokolovi Zone. The allocation of a Tenuicostata Subzone (with two horizons: neoburgense and puschi) in the Pseudoscythica Zone is proven. The neoburgense horizon may be correlated with the ciliata and penicillatum horizons of Neuburg and, probably, with the Semiforme Zone. The findings of Lingulaticeras blaschkei, Pseudolissoceras, and Sutneria in the Panderi Zone of the Middle Tithonian suggest that the base of the Middle Volgian may not be younger than the Middle Tithonian Fallauxi Zone

THE BOREAL-TETHYAN BIOGEOGRAPHICAL MOLLUSC ECOTONE IN EUROPE DURING THE JURASSIC-CRETACEOUS TRANSITION

Late Jurassic and earliest Cretaceous molluscs of the northern hemisphere were distinctly differentiated geographically into Boreal taxa, usually north of 50° N, and Tethyan taxa, usually south of 45° N. Between these latitudes certain areas were displaced from time to time, although the biogeographical ecotone was stable. The magnitude of the ecotone and the migration of molluscs inside the ecotone varied in time and space, in direction (unidirectional and bidirectional) and intensity (expansion and "isolate straying"). The frequency of the Boreal-Tethyan migrations of molluscs is explained by eustacy and by geographical barriers existing between the Northern Caucasus and Middle-Russian basins

Non-reciprocal light scattering by lattice of magnetic vortices

We report on experimental study of optical properties of two-dimensional square lattice of triangle Co and CoFe nanoparticles with a vortex magnetization distribution. We demonstrate that intensity of light scattered in diffraction maxima depends on the vorticity of the particles magnetization and it can be manipulated by applying an external magnetic field. The experimental results can be understood in terms of phenomenological theory.Comment: 10 pages, 4 figure