Subdivision Of Sediments Research Articles

Barguzin rift valley: Sedimentogenesis and paleogeography (Baikalian area, Russia)

Research on subdivision of sediments in the Barguzin rift valley based on paleofluvial studies and paleogeographic reconstructions showed that the deposits of high terraces (VII–IV) formed mostly in alluvial-lacustrine environments, whereas the lower terraces (III–I) are essentially fluvial. The Late Cenozoic activation of the tectonic movements was marked by the rise of the Baikal Lake level and the lake water inundation into river valleys and dry depressions. During the Late Pleistocene the flood water flowed gradually, a set of low terraces being formed in the process.

Vetygala Exposure: the problem of the lower boundary of Pleistocene

The presented results of palaeomagnetic and lithological investigations of the Vetygala Exposure are one more attempt to solve the problem of the lower boundary of the Pleistocene in Eastern Lithuania. Five lithological complexes distinguished in the deposit sequence of the Vetygala Exposure of up to 22 metres height were studied by means of lithology and palaeomagnetism. Carbonate analysis undertaken showed that the amount of carbonates is increasing only in the uppermost part of outcrop, but some carbonate content in the lower part suggests that the sediments in the Vetygala Exposure could have formed at the beginning of the Pleistocene. Results of measurements of the magnetic susceptibility of sediments and the determination of the anisotropy of magnetic susceptibility and remanent magnetisation for orientated samples from clayey silt interlayers demonstrate that changes of Earth’s magnetic field polarity were frequent during the sediments deposition and maintain about a relatively long period of sedimentation. The results of recent lithological and palaeomagnetic studies do not give a straight answer about the stratigraphical identity of investigated sediments. Thus, the stratigraphical subdivision of sediments in the Vetygala Exposure and their correlation with neighbouring geological sections are still open to variable interpretation.

Quaternary Palynostratigraphy of the Bulgarian Black Sea coastal area

The palynological method is one of the main biostratigraphic methods. Pollen analysis of marine sediments offers the possibility of obtaining long and presumably continuous records of coastal vegetation that are the source of plant microfossils found in the marine basins. Such sequences provide opportunity to develop complete and high-resolution records of terrestrial events. The stratigraphic subdivision of sediments from the western Black Sea area is based on qualitative interpretation of the pollen and spore assemblages, and the vertical and spatial distribution of selected indicator taxa