On the Impact of Insufficient Atmospheric Moistening on the Low Annual Discharge of Large Rivers in European Russia

Water Resources - The regional peculiarities of annual atmospheric moistening in European Russia are investigated using Standardized Precipitation and Evapotranspiration Index (SPEI). It was found...     

Multiple phases of North African humidity recorded in lacustrine sediments from the Fazzan Basin, Libyan Sahara

The Fazzan Basin of south-west Libya is at present arid with less than 20 mm of rainfall per annum. However, regionally extensive limestones, lacustrine sands and coquina (fossiliferous carbonate rock) deposits show that the Fazzan Basin previously contained a large palaeolake, indicating that the climate in the past was more humid. Optically stimulated luminescence (OSL) dating techniques have been applied to key lacustrine deposits within the basin in an attempt to provide an internally consistent chronology for this humidity record. Results indicate that palaeolake sediments within the Fazzan Basin record a very long history of palaeohydrological change, ranging from present day arid conditions to humidity capable of sustaining a lake with an approximate area of 76,250 km². The existence of humid periods in mid oxygen isotope stage 5 and the early Holocene is confirmed. An older lacustrine event, tentatively correlated to oxygen isotope stage 11, is also recognized. In addition, evidence is presented for at least two humid phases beyond the age range over which the conventional OSL dating technique is applicable. This study demonstrates that OSL dating of palaeolake sediments within the Fazzan Basin offers the potential to provide a detailed record of North African humidity spanning several glacial–interglacial cycles.     

Tentative study of flow patterns in the North Aegean Sea using NOAA-AVHRR images and 2D model simulation

A statistical technique for image processing, the maximum cross correlation (MCC) method, was utilized on sequences of NOAA-AVHRR thermal data in order to explore the surface advective current dynamics at the discharge region of the Hellespont in the North Aegean Sea. A 2D numerical flow model was also used in order to simulate the barotropic flow pattern of the surface water layer. The model was forced with diurnal wind fields obtained for the same period as the satellite infrared images. The currents (magnitude and direction) derived from the two methods compare satisfactorily despite the fact that some model simplifications were made.     

Radiocarbon dating of quaternary loess deposits,Banks Peninsula,Canterbury, New Zealand

Quaternary loess deposits containing charcoal and in situ organic matter constituents from Banks Peninsula, New Zealand, were subjected to various physical and chemical treatments before radiocarbon assay. A stepwide procedure was used in which each component was radiocarbon dated before and after the treatments were applied. The criterion adopted for judging the effectiveness of a treatment is an increase in the radiocarbon age of loess layer. On this basis the oldest and therefore the most reliable date was obtained from the intra-loess charcoal and its humic acid extract. By comparison, the radiocarbon ages of organic matter constituents of the whole or partitioned loess were much younger, and are considered to represent only average ages for the particular layers concerned. No advantage was gained by dating the carbon-enriched clay-humus fraction as opposed to whole loess samples. There is an apparent conflict between our dates and current interpretation of loess stratigraphy and chronology in the South Island of New Zealand, which requires further investigation. This uncertainty apart, the upper layers of multiple loess deposits are clearly much older than earlier reports indicate, and it follows that the correlation of these deposits with late-glacial events both within and beyond New Zealand is even more tenuous and unreliable than previously thought to be the case.     

Exhumed fault-bounded Alpine blocks along the Periadriatic lineament: the Eder unit (Carnic Alps, Austria)

The Eder unit in the Carnic Alps, which is situated immediately south of the Periadriatic lineament (PL), represents a fault-bounded block consisting of a low-grade (up to 400?°C, indicated by epizonal illite “crystallinity” values, recrystallized quartz, and non-recrystallized white mica) metamorphic Paleozoic metasedimentary sequence. Until now, it has been assumed to represent a separate Variscan nappe. The rocks of the Eder unit show a strong E- to W-oriented stretching lineation on steep foliation planes (D₁) subparallel to the PL. D₁ structures originated near the temperature peak of metamorphism, and shear sense indicators show dextral ductile shear parallel to the PL. Tight mesoscale D₂ folds formed on the cooling path. K–Ar and Ar–Ar ages from newly formed white mica cluster around 32–28 and 18–13 Ma and suggest a two-stage Tertiary history of the Eder unit. We interpret the Eder unit as a fault-bounded block formed during Oligocene large-scale dextral shearing along the PL (near T_max) and exhumed in mid-Miocene times during another phase of activity along the PL. Its nature as a separate Variscan nappe is questioned.     

A New Theropod Dinosaur (Theropoda,Dromaeosauridae) from the Late Cretaceous of Tajikistan

Doklady Earth Sciences - A new dromaeosaurid theropod dinosaur, Kansaignathus sogdianus gen. et sp. nov., is described based on a dentary from the Yalovach Formation (Santonian) at Kansai locality...     

Influence of alcohols on the extraction of cerium(IV) by Aliquat-336 in kerosene

Tricaprylmethylammonium chloride (Aliquat-336) diluted with kerosene was used to extract cerium(IV) from nitric acid medium. Various alcohols were used as modifiers to overcome the third phase problem. The different parameters affecting the extraction process including nitric, nitrate, hydrogen ion, extractant and metal concentrations as well as the temperature were separately investigated. The effect of the investigated alcohols on the extraction process was also studied in detail at two different concentrations and correlated to their physical constants. Based on the obtained results, the extraction equilibrium was deduced and the optimum conditions for the extraction of cerium(IV) were proposed. The method was tested and applied to the separation of cerium from the hydrous oxide cake resulting from monazite sand.     

A Local Anomaly of the Stress State of the Earth’s Crust before the Strong Earthquake (M = 7.1) of July 5, 2019, in the Area of Ridgecrest (Southern California)

Doklady Earth Sciences - The evolution of the stress–strain state of the Earth’s crust in Southern California during the preparation period (from January 1, 2019 until August 15, 2019)...