Search

This paper presents the results of a study of rare earth element (REE) fractionation trends in Quaternary mammal remains with the aim to test stratigraphic provenance. The primary aim was to find a solution to the problem of the formation of small mammal disharmonious associations, which is closely connected to the problem of diagnostics of redeposited paleontological material. REE were analyzed from the tooth enamel of small mammal fossils and sediments collected from five stratigraphic units (Ust‐Oda section of Upper Pleistocene terrestrial sediments, Fore‐Baikal area, Siberia). The Ust‐Oda is currently the only known section in the region where a fixed stratigraphic sequence of the Late Pleistocene to Holocene marine isotopic stages (MIS 5–1) occurs. The results for REE signatures of tooth enamel enable us to draw conclusions regarding changes in physical and chemical environmental conditions during diagenesis and afford the possibility of applying geochemical factors signifying REE fractionation to sample classification. This, in turn, allowed us to establish that some small mammal remains found in sediments belonging to the Ust‐Oda section have been redeposited. [ABSTRACT FROM AUTHOR]

The potential of image-dependent gamut mapping as a constrained optimization problem is examined. Results suggest that image-dependent gamut mapping gives good mapping results and avoids visual artifacts.

The article describes a robust algorithm for the multitude of images in a typical color management workflow that allows the subsequent improvement of existing global gamut mappings. The spatial methods can be successfully added to existing gamut mapping algorithms with a substantial gain in perceived image quality.

Abstract Background In aerodynamic levitation, solids and liquids are floated in a vertical gas stream. In combination with CO2-laser heating, containerless melting at high temperature of oxides and silicates is possible. We apply aerodynamic levitation to bulk rocks in preparation for microchemical analyses, and for evaporation and reduction experiments. Results Liquid silicate droplets (~2 mm) were maintained stable in levitation using a nozzle with a 0.8 mm bore and an opening angle of 60°. The gas flow was ~250 ml min-1. Rock powders were melted and homogenized for microchemcial analyses. Laser melting produced chemically homogeneous glass spheres. Only highly (e.g. H2O) and moderately volatile components (Na, K) were partially lost. The composition of evaporated materials was determined by directly combining levitation and inductively coupled plasma mass spectrometry. It is shown that the evaporated material is composed of Na > K >> Si. Levitation of metal oxide-rich material in a mixture of H2 and Ar resulted in the exsolution of liquid metal. Conclusions Levitation melting is a rapid technique or for the preparation of bulk rock powders for major, minor and trace element analysis. With exception of moderately volatile elements Na and K, bulk rock analyses can be performed with an uncertainty of ± 5% relative. The technique has great potential for the quantitative determination of evaporated materials from silicate melts. Reduction of oxides to metal is a means for the extraction and analysis of siderophile elements from silicates and can be used to better understand the origin of chondritic metal.

Chytridiomycosis, a disease induced by the chytrid fungi Batrachochytrium dendrobatidis (Bd) and B. salamandrivorans (Bsal), has strongly contributed to the ongoing worldwide amphibian conservation crisis. While Bd infection has caused amphibian declines for decades on several continents, Bsal is a novel threat to Central European salamanders and newts, being responsible for the collapse of Fire Salamander populations in the Netherlands, Belgium, and Germany. However, numerous other parasites causing harm to amphibians exist, yet have received much less attention than the chytrid fungi. The goal of the present study was to contribute to the understanding of declines of the Green Toad, Bufotes viridis, at its northwestern distribution border, in the area of Cologne, Germany. We combined the data from four years of Bd monitoring with a metabarcoding approach to detect other, mainly unicellular parasites, from amphibian feces and environmental samples, and also report results from Bsal testing in 2019. Skin swabs of approximately 280 amphibians were tested for Bd and 66 for Bsal, and 150 cloacal swabs and environmental samples from five sites were tested for other pathogens and parasites.We found Bd in all sampled locations with high prevalences and partly high individual infection loads but without clinical signs of chytridiomycosis. None of the samples tested for Bsal was positive for this pathogen. We further detected eight additional potential amphibian pathogens from fecal samples: three metamonads (Tritrichomonas augusta, Trichomitus batrachorum and Hexamita inflata), three ciliates (Balantidium duodeni, Nyctotherus cordiformis and N. hubeiensis), one stramenopile (Blastocystis sp.) and one metazoan (the nematode Rhabdias ranae). In the environmental samples, we detected OTUs of nine organisms potentially harmful for amphibians: Blastocystis sp., Hexamita inflata, Tritrichomonas augusta, Trichomitus batrachorum, two oomycetes (Leptolegnia sp., Saprolegnia sp.), two ichthyosporeans (Amphibiocystidium ranae, Anurofeca sp.) and the myxozoan Myxobolus sp. [ABSTRACT FROM AUTHOR]

Three synthetic reference glasses were prepared by directly fusing and stirring 3.8 kg of high‐purity oxide powders to provide reference materials for microanalytical work. These glasses have andesitic major compositions and are doped with fifty‐four trace elements in nearly identical abundance (500, 50, 5 µg g−1) using oxide powders or element solutions, and are named ARM‐1, 2 and 3, respectively. We further document that sector‐field (SF) ICP‐MS (Element 2 or Element XR) is capable of sweeping seventy‐seven isotopes (from 7Li to 238U, a total of sixty‐eight elements) in 1 s and, thus, is able to quantify up to sixty‐eight elements by laser sampling. Micro‐ and bulk analyses indicate that the glasses are homogeneous with respect to major and trace elements. This paper provides preliminary data for the ARM glasses using a variety of analytical techniques (EPMA, XRF, ICP‐OES, ICP‐MS, LA‐Q‐ICP‐MS and LA‐SF‐ICP‐MS) performed in ten laboratories. Discrepancies in the data of V, Cr, Ni and Tl exist, mainly caused by analytical limitations. Preliminary reference and information values for fifty‐six elements were calculated with uncertainties [2 relative standard error (RSE)] estimated in the range of 1–20%. [ABSTRACT FROM AUTHOR]

The 26 km diameter Nördlinger Ries is a complex impact structure with a ring structure that resembles a peak ring. A first research drilling through this "inner crystalline ring" of the Ries was performed at the Erbisberg hill (SW Ries) to better understand the internal structure and lithology of this feature, and possibly reveal impact‐induced hydrothermal alteration. The drill core intersected the slope of a 22 m thick postimpact travertine mound, before entering 42 m of blocks and breccias of crystalline rocks excavated from the Variscan basement at >500 m depth. Weakly shocked gneiss blocks that show that shock pressure did not exceed 5 GPa occur above polymict lithic breccias of shock stage Ia (10–20 GPa), with planar fractures and planar deformation features (PDFs) in quartz. Only a narrow zone at 49.20–50.00 m core depth exhibits strong mosaicism in feldspar and {101¯2} PDFs in quartz, which are indicative of shock stage Ib (20–35 GPa). Finally, 2 m of brecciated Keuper sediments at the base of the section point to an inverse layering of strata. While reverse grading of clast sizes in lithic breccias and gneiss blocks is consistent with lateral transport, the absence of diaplectic glass and melt products argues against dynamic overthrusting of material from a collapsing central peak, as seen in the much larger Chicxulub structure. Indeed, weakly shocked gneiss blocks are rather of local provenance (i.e., the transient crater wall), whereas moderately shocked polymict lithic breccias with geochemical composition and 87Sr/86Sr signature similar to Ries suevite were derived from a position closer to the impact center. Thus, the inner ring of the Ries is formed by moderately shocked polymict lithic breccias likely injected into the transient crater wall during the excavation stage and weakly shocked gneiss blocks of the collapsing transient crater wall that were emplaced during the modification stage. While the presence of an overturned flap is not evident from the Erbisberg drilling, a survey of all drillings at or near the inner ring point to inverted strata throughout its outer limb. Whether the central ring of the Ries represents remains of a collapsed central peak remains to be shown. Postimpact hydrothermal alteration along the Erbisberg section comprises chloritization, sulfide veinlets, and strong carbonatization. In addition, a narrow zone in the lower parts of the polymict lithic breccia sequence shows a positive Eu anomaly in its carbonate phase. The surface expression of this hydrothermal activity, i.e., the travertine mound, comprises subaerial as well as subaquatic growth phases. Intercalated lake sediments equivalent to the early parts of the evolution of the central crater basin succession confirm a persistent impact‐generated hydrothermal activity, although for less time than previously suggested. [ABSTRACT FROM AUTHOR]