Mg-enriched erythrite from Bou Azzer,Anti-Atlas Mountains,Morocco: geochemical and spectroscopic characteristics

Mineralogy and Petrology - Supergene Mg-enriched erythrite, with an average composition (Co2.25Mg0.58Ni0.14Fe0.04Mn0.02 Zn0.02) (As1.97P<0.01O8)·8H2O, accompanied by skutterudite,...     

Trace elements in alluvia of the upper Vistula as indicators of palaeohydrology

In the Vistula valley near Góra, at the northern foreland of the Carpathians Mountains, there are young alluvia deposited in the historical period. These alluvia are difficult to date precisely because of the lack of organic interbedded material. In the Vistula drainage basin upstream of Góra since the second half of 18th century small centres of metal, textile, motor, and petrochemical industries have been developed. Concentrations of trace elements such as: Cr, Mn, Co, Ni, Cu, Zn, Cd, Pb, and of some macroelements were used as indicators of the age of different alluvial fills. The main part of the Vistula valley floor was built up by sediment accumulation before the development of industry but after the medieval phase of rural colonization of the Carpathians. Deposits filling the abandoned channels dissecting the valley floor have an increased content of some trace elements and deposits date from the second half of the 18th century, when the first foundries and blacksmith's shops were developed. A drastic increase of concentration of the most abundant trace elements in the youngest alluvial fill indicates that the fill dates from the last decade of rapid industrial development.     

A GIS-based WFD oriented typology of shallow micro-tidal soft bottom using wave exposure and turbidity mapping

Our GIS based project aims at producing a classification scheme to develop a typology of the bottom of the Bay of Gdansk in the southern Baltic. The typology was based on the abiotic factors which are used to define water body types by the European Water Framework Directive (WFD). Significance analysis of particular factors has shown that within the discussed area wave exposure seems to play the most important role. All other factors are to a greater or lesser degree correlated with these two. Taking into consideration the shallows and the varied coastline of the investigated area it was decided to make use of the SWAN numerical wave model to determine the influence of wave impact upon the bottom. The model was used to produce raster maps of orbital velocity near the bottom for each wind scenario. With the help of the GIS analysis the maps were turned into layers: the mean velocity and the maximum velocity at the bottom. To produce the layer of yearly amount of solar radiation a GIS model was built which main parameters were the layer of depth and three layers of turbidity for three seasons. The layers of the maximum orbital velocity and of the solar radiation at the bottom were then used in a classificatory procedure consisted in an iterative sequence of the three following steps: cluster formation, dendrogram analysis and classification using the maximum likelihood method. Ecological importance of the classification has been obtained by means of the aggregation of a part of classes based upon the statistics calculated for them within the GIS system with the help of the zonal function out of the following parameters: salinity, depth, mean and maximum orbital velocity at the bottom, temperature differences between warm and cold seasons, solar radiation, and type of sediments. The method proposed here makes it possible to produce high resolution thematic maps of the bottom even with incomplete data cover of the investigated area.     

Strong, Variable Circular Polarization in PKS 1519–273

It is found that velocity shear enables the extraction of kinetic energy from the background flow by Dust-Acoustic waves. It is also shown that the velocity shear leads to the appearance of a new mode of the dust particles collective behaviour, called shear dust vortices. This revised version was published online in July 2006 with corrections to the Cover Date.     

Organic-walled Microfossils from the Early Middle Cambrian sediments of the Holy Cross Mountains, Poland: Possible Implications for Sedimentary Environment in the SE Margin of the Baltica

An association of organic-walled microfossils consisting of filamentous cyanobacteria, algal coenobia and acanthomorphic acritarch have been documented from non-calcareous claystones and mudstones of the Pepper Mountains Shale Formation(PMSF), located in its stratotype area in the Pepper Mountains, which are part of the Holy Cross Mountains in Poland. These sediments represent the oldest strata of the ?ysogóry Unit, deposited on the edge of the East European Craton(Baltica). Non-branched, ribbon-like and thread-like cyanobacteria trichomes exhibit morphological similarities to families Nostocaceae and Oscillatoriaceae. Cells assembled in rounded to irregular clusters of monospecific agglomerations represent multicellular algal coenobia, attributed to the family Scenedesmaceae. The co-occurrence of acritarchs belonging to species as Eliasum llaniscum, Cristallinium ovillense and Estiastra minima indicates that the studied material corresponds to the lower Middle Cambrian. Deposition of the PMSF took place in shallow marine environment, influenced by periodical freshwater inputs. The varying degree of coloration of organic-walled microfossils is interpreted in this study as factor indication of possible different source of their derivation. Dark brown walls of cells assembled in algal coenobia might have sustained previous humification in humid, terrestrial environments, which preceded their river transport into the sea together with nutrients, causing occasional blooms of cyanobacteria in the coastal environment and the final deposition of both groups of organisms in marine deposits.     

An Iterative Method for Calculation of Wind Profiles at the Mesoscale and Microscale

Boundary-Layer Meteorology - Space–time correlations are fundamental to statistical theories and turbulence modelling. However, experimental studies of space–time correlations are often...     

Origin and post-glacial evolution of surface cracks: A case study from the area of the Last Glaciation,north-eastern Poland

The analysis of LiDAR-based digital elevation models revealed the existence of groups of longitudinal fractures in the ground in northern Poland at the limit of the ice sheet's extent during its last maximum. Our research on the closed elongated depressions (CEDs) of the Jedwabno test field (Szuć site, north-east Poland) focuses on explaining their origins and their post-glacial history. This region was covered by an ice sheet and glacitectonically active during the Vistulian, and at least some surface fractures are possible witnesses to this activity. Using geomorphological mapping, sedimentological and geophysical research, we assumed it was related that the origin of these features here is associated with groundwater migration at the end of the Vistulian glaciation or later when groundwater flow intensified due to a rapid climate warming that caused permafrost to melt. The thawing of permafrost caused to transition from continuous permafrost to discontinuous, which in turn created groundwater flow that was probably responsible for the development of the surface cracks (fractures). Radiocarbon, palaeobiological (pollen, Cladocera) and geochemical studies allowed for an estimation of the formation time of these unique surface cracks in the Older Dryas. Prevailing conditions were also reconstructed for the later dynamic changes of the end of the Late Vistulian glaciation and in the Late Holocene until the Subatlantic Period (Megalayan stage). The surface cracks with steep slopes, despite their small area, are extraordinary sedimentation traps that have, in a special way, retained an almost complete record of the environmental and climate changes of the Late Glacial. There are sedimentological gaps in the Holocene, especially after the Preboreal (old part of the Greenlandian Stage), caused by changes in water levels, aeolian processes and human activity.     

Interstellar Scintillation and Annual Cycles in the BL Lac Source PKS 1519-273

We have measured annual cycles in the time scales of the rapid, intra-day variability of the total and circularly polarized flux density, of the unusual BL Lac source PKS 1519–273 at 4.8 and 8.6 GHz. This data was collected at the ATCA over the last seven years, and establishes unequivocally interstellar scintillation as the principal mechanism responsible for this cm-wavelength intra-day variability.     

The Middle Pleistocene glaciolacustrine environment of an ice‐dammed mountain valley,Sudeten Mountains,Poland

This article reports on an Early Saalian proglacial lake formed between the Scandinavian Ice Sheet and the front of the Sudeten Mountains, Poland. Sediments investigated at Mys?ów point to a transition from glacifluvial to glaciolacustrine environments. The bulk of the sediments was deposited in deep‐water Gilbert‐type deltas (A–E complexes). A delta plain (topset) gradually passes into a subaerial plateau and then a clastic shoreline and the subaquatic slope of a prograding delta (foreset). The glaciolacustrine lithofacies represent a number of lake‐basin environments, from marginal subaqueous slopes to distal parts of a subaqueous fan. Glaciolacustrine and glaciodeltaic deposits locally reach ?50–70 m in thickness. Analyses of A–E complexes indicate that the lake existed for more than 130 years and that its origin and evolution were closely connected with the ice front. This case study records lake sedimentation at an ice‐sheet margin with cohesionless gravity flows, turbidity currents, debris‐avalanching and, to a much lesser degree, parapelagic suspension fall‐out and ice‐raft dumping. In the initial stage, the lake extended more than 10 km to the south, and the deposition was relatively slow. In the second stage, recession of the ice sheet caused rapid growth of a delta. The third and ultimate stage coincided with the final glacial recession, with rapid deposition occurring only on the lake bottom. The model of the glaciolacustrine environment presented here may also be applicable to many other proglacial lakes in mountain areas.     

<Emphasis Type="Italic">Pleurozium schreberi</Emphasis> of the Tatra mountains (Poland) used as a bioindicational system for observing long range atmospheric transport of chemical elements

Concentrations of the elements Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, V and Zn were measured in the moss Pleurozium schreberi from the Tatra National Park, one of the most protected regions in Poland. The moss samples were collected at different elevations between 860 and 2220 m a.s.l. P. schreberi was used as bioindicator for long range transported atmospheric pollution investigating the hypothesis that elevation influences the concentrations of elements in this moss. Principal component and classification analysis (PCCA) distinguished between mosses from the highest and the lowest elevations and mosses from West/East oriented valleys. P. schreberi from the highest elevations contained the highest concentrations of Cd, Cu, Cr, Fe, Mn, Pb, V and Zn. P. schreberi from the lowest elevation contained the highest concentration of K. P. schreberi from West/East oriented valleys contained the highest concentrations of Ni and Co. P. schreberi from the Tatra National Park, one of the most protected areas in Poland, receives metals originating from long distance aerial transport.