Stratigraphic and lithologic characteristics of Pleistocene fluvial deposits in the Danube and Sava riparian area near Belgrade (Serbia)

The Quaternary sediments in the Danube and Sava riparian area near Belgrade have a considerable thickness. Several categories of deposits (fluvial-lacustrine, fluvial and aeolian) of Pliocene and Quaternary age have been identified. Their thickness, granulometric composition and paleontological features change depending on the distance from the recent Danube and Sava riverbeds. The Pleistocene fluvial deposits are underlain by sediments of the Late Miocene (Sarmatian and Pannonian) or the Plio-Pleistocene age, and are overlain by fluvial-palustrine deposits of the Pleistocene age and recent alluvial deposits. Pleistocene fluvial deposits that form a major part of the Quaternary sediments, have a great significance, since they are proved to be excellent collectors of ground water. Although these deposits are at lower altitudes in the area of Srem, they could be correlated with the high Danube and Morava terraces in Serbia and Drava in Croatia on the basis of their lithologic and paleontological features.     

Environmental conditions of the Laptev Sea region in the late postglacial time

The comparison between the first results of comprehensive micropaleontological analysis (pollen, spores, foraminifera, and ostracods) and those of radiocarbon dating (AMS¹⁴C) for the sediments of the eastern inner shelf of the Laptev Sea (the core collected from depth of 37 m) indicates that considerable changes in natural conditions in the sea and on land coincide in time and refer to the time period of 1500–1700 years B.P. This period is characterized by changes in microfossils: appearance of thermophilic pollen and planktonic foraminifera and increase in total number of benthic foraminifera and ostracods. Intense warming and humidification of the climate reconstructed for this 200-year period promoted the expansion of large-shrub tundra. Summer air temperatures were lower than that in the peak mid-Holocene climatic optimum by 2°–3°C, but 1°C higher than the present-day temperature. An estuary freshwater basin developed: it was strongly affected by river discharge, but North Atlantic waters also intensely penetrated here in short-term intervals. In general, the studied microfossil complex reflects the relatively stable environmental conditions and decrease in seawater salinity in the eastern part of the Laptev Sea shelf during the last 2300 years.     

Paleogene and Neogene reference sections of Eastern Kamchatka

The available lithological and paleontological data are used to characterize key Cenozoic marine sections in two lithological–facies zones (Kamchatskii Mys Peninsula and southern Valaginskii Range) of the poorly investigated Eastern Kamchatka lithotectonic zone with their correlation and reconstruction of depositional environments at the ocean–continent transition during the Paleogene and Neogene.     

Upper Neopleistocene ostracods from the southeastern West Siberian Plain and their stratigraphic significance

In the upper Neopleistocene of the southeastern West Siberian Plain, two ancillary biostratigraphic units by ostracods in the rank of faunal beds, namely, the Cypridopsis vidua–Herpetocypris reptans Beds (Ermakovo Horizon and the lower part of the Karginsky Horizon) and the Ilyocypris pustulata Beds (Karginsky Horizon), are recognized for the first time. The age of the Ilyocypris pustulata Beds is substantiated by a series of radiometric datings. The Eucypris pigra–Cyclocypris laevis–C. triangula ostracod assemblage from the upper part of the Sartan Horizon, whose age is also justified by a radiometric date, is characterized. The new data on ostracods supplement the materials available on this group of fauna and refine the Quaternary regional stratigraphic scheme of the West Siberian Plain.     

Flora from the Induan stage (Lower Triassic) of Middle Siberia

The first data on the taxonomic composition of the Induan flora of Siberia are presented. The investigation of Triassic reference sections in northern Siberia (eastern Taimyr, Lena–Anabar Trough, Verkhoyansk region) and correlation with volcano-sedimentary complexes of the Tungus and Kuznetsk basins made it possible to establish for the first time the taxonomic composition of the flora from the Induan Stage of Siberia. Its composition is heterogeneous, forming two large plant formations, which occupied different ecological niches. On the eastern coastal-marine margins of Siberia (eastern Taimyr, Olenek coast, Verkhoyansk region), the Induan flora was largely characterized by lepidophytic (Tomiostrobus) plants, while in the intracontinental areas (Tungus and Kuznetsk basins, partly Verkhoyansk region), it was characterized by Equisetales–Filicales communities.     

Mutual interaction of redox pairs in silicate melts: Equilibria involving metallic phases

Mutual interaction of redox pairs resulting in the origin or decomposition of a metal phase is analyzed based on the concept of intrinsic oxygen fugacity. Reactions are suggested that may be responsible for the synthesis (or decomposition) of submicrometer-sized metal nuggets when experimental melts are quenched and can explain the possible crystallization of Pt—Fe alloys when basaltic melts cool and elucidate the nature of color of Au-bearing ruby glass. Possible disproportionation reactions of certain lower oxides into a higher oxide and respective metal in cooled silicate melts are discussed.     

Shoreline variability of an urban beach fronted by a beachrock reef from video imagery

This contribution presents the results of a study on the shoreline variability of a natural perched urban beach (Ammoudara, N. Crete, Greece). Shoreline variability was monitored in high spatio-temporal resolution using time series of coastal video images and a novel, fully automated 2-D shoreline detection algorithm. Ten-month video monitoring showed that cross-shore shoreline change was, in some areas, up to 8 m with adjacent sections of the shoreline showing contrasting patterns of beach loss or gain. Variability increased in spring/early summer and stabilized until the end of the summer when partial beach recovery commenced. Correlation of the patterns of beach change with wave forcing (as recorded at an offshore wave buoy) is not straightforward; the only discernible association was that particularly energetic waves from the northern sector can trigger changes in the patterns of shoreline variability and that increased variability might be sustained by increases in offshore wave steepness. It was also found that the fronting beachrock reef exerts significant geological control on beach hydrodynamics. Hydrodynamic modelling and observations during an energetic event showed that the reef can filter wave energy in a highly differential manner, depending on its local architecture. In some areas, the reef allows only low-energy waves to impinge on the shoreline, whereas elsewhere penetration of higher waves is facilitated by the low elevation and limited width of the reef or by the presence of an inlet. Wave/reef interaction can also generate complex circulation patterns, including rip currents that appeared to be also constrained by the reef architecture.     

Laboratory Estimation of Rock Joint Stiffness and Frictional Parameters

Numerical modeling of complex rock engineering problems involves the use of various input parameters which control usefulness of the output results. Hence, it is of utmost importance to select the right range of input physical and mechanical parameters based on laboratory or field estimation, and engineering judgment. Joint normal and shear stiffnesses are two popular input parameters to describe discontinuities in rock, which do not have specific guidelines for their estimation in literature. This study attempts to provide simple methods to estimate joint normal and shear stiffnesses in the laboratory using the uniaxial compression and small-scale direct shear tests. Samples have been prepared using rocks procured from different depths, geographical locations and formations. The study uses a mixture of relatively smooth natural joints and saw-cut joints in the various rock samples tested. The results indicate acceptable levels of uncertainty in the calculation of the stiffness parameters and provide a database of good first estimates and empirical relations which can be used for calculating values for joint stiffnesses when laboratory estimation is not possible. Joint basic friction angles have also been estimated as by-products in the small scale direct shear tests.     

Investigation of Cycle Time Segments of Dragline Operation in Surface Coal Mine: A Statistical Approach

Dragline is highly capital intensive equipment to procure, operate and maintain in any surface mining operation. Given this, every second of operation of this capital intensive equipment is absolutely important. Improvement of even a single second in the total cycle time has a tremendous bearing on the overall performance of this equipment. In this light, the present paper is an endeavour to critically analyze the cycle time of dragline operations in a major surface coal mine in India. Rigorous statistical analysis has been performed on individual cycle time segments, of complete dragline cycle. The segmental cycle times have been found to be statistically significant and appear to be best represented by lognormal, normal and beta distributions. Furthermore, the mean time of the statistical distribution for segmental cycle time of dragline has revealed the dependence of cycle time on cut geometry and depth. Results have been illustrated in the form of figures, graphs and tables.