Proterozoic VanDieland in Central Victoria: ages,compositions and source depths for late devonian silicic magmas

The Proterozoic to Cambrian VanDieland microcontinent was accreted to mainland Australia at ca 400?Ma, and its northern tip, the Selwyn Block, forms the basement in central Victoria. Here, mainly Late Devonian, silicic magmas were derived from the Selwyn Block and intruded into the shallow crust. We use the phase petrology of Late Devonian, S-type rhyolitic ignimbrites and a xenolith of pelitic migmatite, together with Nd-model ages for the silicic magmatic rocks to constrain the lithological characteristics of the metasedimentary component of the Selwyn Block, to infer minimum depths and temperature conditions here in the Late Devonian, and the likely ages of the source rocks for the S-type magmas. The most abundant source rocks are inferred to be volcaniclastic metagreywackes, with minor metadacites, meta-andesites and metapelites. The metapelitic xenolith cannot have been the source for any of the silicic magmas but constrains the upper amphibolite-facies part of the Selwyn Block to depths around 17?km, where temperatures reached ～775?°C. The older ignimbrite magma was formed by partial melting at perhaps 770?°C and a depth of at least 33?km, while the younger ignimbrite magma formed at ～23?km and 900?°C. These depths suggest source rocks in the Paleoproterozoic to Mesoproterozoic lower parts of the Selwyn Block. Nd-model ages of the silicic magmatic rocks confirm a dominance of Mesoproterozoic to Paleoproterozoic sources. If the inferred rock types in the Mesoproterozoic formations were as current correlations suggest, the sources for the Late Devonian silicic magmas would have to lie in the undocumented Paleoproterozoic basement of the Selwyn Block. Rock types here must include andesitic to dacitic volcanic components as well as volcaniclastic greywackes and minor pelites, which suggests a continental arc setting. The Late Devonian magmatism in the region may record the progression from amphibolite- to granulite-facies conditions during post-orogenic extension, with heat advected to the crust by mantle-derived mafic magmas. These processes would have resulted in mafitisation of the deep Selwyn Block.     

Intrusion of igneous rocks — Physical aspects

Igneous rocks occur in two predominant modes. The plutonic mode is characterized by intrusive emplacement under compressional tectonic stress regimes. The volcanic mode is dominated by the eruption of large volumes of magma through fault controlled dyke structures in extensional tectonic stress regimes.Those typical intrusive phenomena are discussed in the light of the physical parameters like the dynamic-thermal regime of the lithosphere, the nature and source of buoyant forces as well as mechanical aspects of subsolidus flow of rocks.Twodimensional numerical models on the basis of typical parameter specifications and by means of a coupled dynamic-thermal physical approximation are presented. The simulation of buoyantly-driven diapiric intrusions has been adopted to derive parameters which are critically controlling the transport and emplacement of intrusion under surroundings of variable viscosity. Both sill-type and batholith-type structures are presented and discussed with respect to their predominant dependence on mechanical and physical conditions.

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Zusammenfassung Magmatische Gesteine treten in zwei vorherrschenden Erscheinungsformen auf. Die Plutonite sind charakterisiert durch eine intrusive Platznahme unter kompressiven tektonischen Spannungsbedingungen. Die Vulkanite werden beherrscht von gro\en Volumina eruptierten Magmas, das vorzugsweise durch weiträumige Bruchsysteme unter Zugspannungsbedingungen aufsteigt.Derartige magmatische Phänomene werden aus der Sicht physikalischer Parameter wie dynamisch-thermische Bedingungen der Lithosphäre, der Natur und des Ursprungs von Auftriebskräften sowie der Mechanik von Gesteinsformationen diskutiert.Es werden zweidimensionale numerische Modellrechnungen auf der Grundlage typischer Parameterbereiche vorgestellt. Die Rechnungen basieren auf einer dynamisch-thermischen Approximation von Flie\vorgängen. Sie werden eingesetzt zur Untersuchung von diapirartigen Intrusionsvorgängen, die durch Dichteinversionen angetrieben sind. Hierbei sollen die Parameter bestimmt werden, die Aufstieg und Platznahme der Intrusionen bestimmen. Die Umgebung ist charakterisiert durch eine vorgebbare variable Viskosität. Sowohl linsenförmige Sill-Strukturen als auch typische Batholith-Strukturen werden mathematisch simuliert. Ihr Zusammenhang mit den strukturbestimmenden Parametern wird aufgezeigt.

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Résumé Les roches magmatiques se répartissent en deux catégories principales: la catégorie plutonique est caractérisée par une mise en place dans des régimes de contraintes tectoniques compressives; la catégorie volcanique est dominée par l'éruption de volumes importants de magma à travers des systèmes de cassures dans des régimes de contraintes tectoniques d'extension.Ces phénomènes intrusifs sont discutés à la lumière de paramètres physiques tels que: le régime thermique et dynamique de la lithosphère, la nature et l'origine des forces ascensionnelles, ainsi que les aspects mécaniques du fluage sub-solidus des roches.Les auteurs présentent des modèles numériques bidimensionnels basés sur des domaines paramétriques typiques, au moyen d'une approximation dynamo-thermique de phénomène d'écoulement. La simulation d'intrusions diapiriques permet de déduire les paramètres qui déterminent le transport et la mise en place d'une intrusion dans diverses conditions de viscosité de l'encaissant. Les structures de type sill et de type batholite sont discutées en relation avec les conditions mécaniques et physiques dont elles dépendent.

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Spatial distribution of lead and lead isotopes in soil B-horizon, forest-floor humus, grass (Avenella flexuosa) and spruce (Picea abies) needles across the Czech Republic

Lead concentrations were determined in samples of soil B-horizon (N = 258), forest-floor humus (O-horizon, N = 259), grass (Avenella flexuosa, N = 251) and spruce (Picea abies, N = 253) needles (2nd year) collected at the same locations evenly spread over the territory of the Czech Republic at an average density of 1 site/300 km². Median Pb concentrations differ widely in the four materials: soil B-horizon: 27 mg/kg (3.3-220 mg/kg), humus: 78 mg/kg (19-1863 mg/kg), grass: 0.37 mg/kg (0.08-8 mg/kg) and spruce needles: 0.23 mg/kg (0.07-3 mg/kg). In the Pb distribution maps for humus, grass and spruce a number of well-known Pb-contamination sources are indicated by unusually high concentrations (e.g., the Pb smelter at Pribram, the metallurgical industry in the NE of the Czech Republic and along the Polish border, as well as the metallurgical industry in Upper Silesia and Europe’s largest coal-fired power plant at Bogatynia, Poland). The ratio ²⁰⁶Pb/²⁰⁷Pb was determined in all four materials. The median value of the ²⁰⁶Pb/²⁰⁷Pb isotope ratio in the soil B-horizon is 1.184 (variation: 1.145-1.337). In both humus and grass the median value for the ²⁰⁶Pb/²⁰⁷Pb isotope ratio is 1.162 (variation: 1.130-1.182), in spruce needles the median ratio is 1.159 (variation: 1.116-1.186). In humus, grass and spruce needles the known contamination sources are all marked by higher ²⁰⁶Pb/²⁰⁷Pb isotope ratios in the maps. Furthermore, the soil B-horizon, humus, grass and spruce needles show distinctly different spatial distribution patterns of the ²⁰⁶Pb/²⁰⁷Pb isotope ratios. The B-horizon does not provide a viable background value for metal concentrations in the O-horizon or plant materials. None of the maps provides evidence for the importance of traffic-related emissions for the observed isotope ratios at the scale of the Czech Republic.     

Klimazeugen aus dem jüngsten Präkambrium und Unterkambrium in S-Marokko

Zusammenfassung In Gesteinen des jüngsten Präkambriums und Unterkambriums (mit einer Diskordanz nach dem pC III) sind im Antiatlas Marokkos wiederholt Anzeichen für eine Sedimentation bei warmem (semiarid bis arid) Klima zu finden. Klimaindikatoren sind Rotsedimente, CaSO₄- und NaCl-Pseudomorphosen sowie Sedimente vom Sabkha-Typ.Paläomagnetische Daten weisen zu dieser Zeit auf Südpolpositionen in diesem Gebiet hin.Vereisungsrelikte in Nachbargebieten entsprechen möglicherweise einer Sedimentationslücke nach dem pC III im Antiatlas.

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In the Antiatlas region of Morocco rocks of Late-Precambrian and Lower-Cambrian age (with a discordance after the pC III) show evidence for sedimentation under warm (semiarid to arid) climate. Climate indicators are redbeds, sabkha-sediments and pseudomorphoses after CaSO₄ and NaCl.Paleomagnetic data showed that at this time southpole positions were distributed in this area.In nearby regions documents of glaciation are possibly correspondend with a time of non-sedimentation after the pC III in the Antiatlas.

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Résumé Les roches du Précambrien supérieur et du Cambrien inférieur de l'Antiatlas du Maroc (avec une discordance après le pC III) présentent de nombreuses évidences d'une sédimentation sous des conditions climatiques chaudes (semiarides à arides). Les indicateurs climatiques sont des couches rouges, des sédiments de sabkha et des pseudomorphoses de CaSO₄ et NaCl.Les études paléomagnétiques démontrent que l'emplacement du pôle sud se trouvait à cette époque dans cette même région.Les restes de glaciation dans les régions voisines paraissent corréspondre à une periode de nonsédimentation après le pC III dans l'Antiatlas.

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— III- ( ) . , CaSO₄ NaCl, Sabkha. , . , , — 800–900 .

     

A statistical retrieval algorithm for root zone soil moisture

An algorithm for the estimation of root zone soil moisture is presented. Global fields of the soil moisture within the uppermost metre of soil are derived with a temporal resolution of 10 days. For calibration, long-term soil moisture observations from the former Soviet Union are used. The variance of the measurements is largely dominated by the spatial variability of the long-term mean soil moisture, while the temporal variability gives comparatively small contribution. Consequently, the algorithm is organised into two steps. The first step concentrates on the retrieval of the spatial variance of the long-term means, which comprises more than 85% of the total soil moisture variability. A major part of the spatial variance can be explained by four easily available fields: the climatological precipitation, land use, soil texture, and terrain slope. The second step of the algorithm is dedicated to the local temporal variability. This part of variability is recovered by using passive microwave data from scanning multichannel microwave radiometre (SMMR) supported by monthly averaged fields of air temperature and precipitation. The 6-GHz channel of SMMR is shown to be severely disturbed by radio frequency interference, so that information from the 10-GHz channel is used instead. The algorithm provides reasonable soil moisture fields which is confirmed by a comparison with independent measurements from Illinois.     

Completeness of citizen science biodiversity data from a volunteered geographic information perspective

Observations of living organisms by citizen scientists that are reported to online portals are a valuable source of information. They are also a special kind of volunteered geographic information (VGI). VGI data have issues of completeness, which arise from biases caused by the opportunistic nature of the data collection process. We examined the completeness of bird species represented in citizen science observation data from eBird and iNaturalist in US National Parks (NPs). We used approaches for completeness estimation which were developed for data from OpenStreetMap, a crowdsourced map of the world. First, we used an extrinsic approach, comparing species lists from citizen science data with National Park Service lists. Second, we examined two intrinsic approaches using total observation numbers in NPs and the development of the number of new species being added to the data-set over time. Results from the extrinsic approach provided appropriate completeness estimations to evaluate the intrinsic approaches. We found that total observation numbers are a good estimator of species completeness of citizen science data from US NPs. There is also a close relationship between species completeness and the ratio of new species added to observation data vs. observation numbers in a given year.     

Remote sensing of cloud liquid water

Summary A method is presented to infer cloud liquid water path (LWP in kg/m²) over the ocean from passive microwave measurements of SSM/I. The algorithm to retrieve LWP is based on simulated satellite observations. They are calculated with a radiative transfer model applied to about 3000 radiosonde ascents over the Atlantic Ocean. Since radiosonde observations do not contain direct information about cloud water and ice, these parameters are parameterized based on relative humidity and temperature using modified adiabatic liquid water density profiles. A multiple linear regression is applied to the simulated radiances and the calculated LWP to derive the algorithm. The retrieval accuracy based on the regression analysis including instrumental noise is 0.03 kg/m². Validation of the LWP-algorithm was pursued through a comparison with measurements of a ground-based 33 GHzmicrowave radiometer on board of R.V. Poseidon during the International Cirrus Experiment 1989 at the North Sea (ICE'89). The LWP values agree within the range of uncertainty caused by the different sampling characteristics of the observing systems. The retrieval accuracy for clear-sky cases determined using colocated METEOSAT data over the North Sea is 0.037 kg/m² and confirms the accuracy estimated from regression analysis for the low liquid water cases.The algorithm was used to derive maps of monthly mean LWP over the Atlantic Ocean. As an example the Octobers of the 5 years 1987–1991 were selected to demonstrate the interannual variability of LWP. The results were compared with the cloud water content produced by the climate model ECHAM-T2 from the Max-Planck-Institut Hamburg.Observations during ICE'89 were used to check the accuracy of the applied radiative transfer model. Brightness temperatures were calculated from radiosonde ascents launched during the overpass of DMSP-F8 in cloud-free situations. The channel-dependent differences range from about –2 to 3 K.The possibility to identify different cloud types using microwave and infrared observations was examined. The main conclusion is that simultaneous microwave and infrared measurements enable the separation of dense cirrus and cirrus with underlying water clouds. A classification of clouds with respect to their top heights and LWP was carried out using a combination of SSM/I derived LWP and simultaneously recorded Meteosat IR-data during ICE'89.With 11 Figures     

Protocol for Quantitative Detection of Elemental Sulfur and Polysulfide Zero-Valent Sulfur Distribution in Natural Aquatic Samples

A HPLC-based protocol has been developed for the determination of zero-valent sulfur (ZVS) speciation, including solid, colloidal elemental sulfur and individual inorganic polysulfides in natural aquatic samples. The protocol includes four experimental procedures: (1) determination of polysulfide speciation by rapid single-phase derivatisation with methyl trifluoromethanesulfonate; (2) determination of the sum of polysulfide and colloidal sulfur by reaction with hydrogen cyanide (cyanolysis); (3) determination of total zero-valent sulfur by treatment with zinc chloride followed by extraction with chloroform; and (4) chromatographic determination of polythionates without sample pre-treatment. With proper sampling and preservation techniques in the field or on board ship, this combination of methods allowed the quantitative determination of: (a) individual polysulfide species; (b) dispersed colloidal sulfur; (c) dispersed solid elemental sulfur; and (d) tetra-, penta- and hexathionates. With minor modification, the method could be expanded to include other polythionates. Sixteen various wet chemical and liquid chromatographic methods were tested on nine synthetic reference samples (including solid elemental sulfur, colloidal elemental sulfur, inorganic polysulfides and polythionates) to establish the optimal protocol. The protocol was further evaluated by analysing the zero-valent sulfur content in microbially-produced sulfur and in sulfur from two natural samples of sulfide-rich seawater from tidal flats pools of the Wadden Sea (Germany).     

Bottled drinking water: Water contamination from bottle materials (glass,hard PET,soft PET), the influence of colour and acidification

A test comparing concentrations of 57 chemical elements (Ag, Al, As, B, Ba, Be, Bi, Ca, Cd, Ce, Co, Cr, Cs, Cu, Dy, Er, Eu, Fe, Ga, Gd, Ge, Hf, Ho, I, K, La, Li, Lu, Mg, Mn, Mo, Na, Nb, Nd, Ni, Pb, Pr, Rb, Sb, Se, Sm, Sn, Sr, Ta, Tb, Te, Th, Ti, Tl, Tm, U, V, W, Y, Yb, Zn and Zr) determined by inductively coupled plasma quadrupole mass spectrometry (ICP-QMS) in 294 samples of the same bottled water (predominantly mineral water) sold in the European Union in glass and PET bottles demonstrates significant (Wilcoxon rank sum test, α = 0.05) differences in median concentrations for Sb, Ce, Pb, Al, Zr, Ti, Th, La, Pr, Fe, Zn, Nd, Sn, Cr, Tb, Er, Gd, Bi, Sm, Y, Lu, Dy, Yb, Tm, Nb and Cu. Antimony has a 21× higher median value in bottled water when sold in PET bottles (0.33 vs. 0.016 μg/L). Glass contaminates the water with Ce (19× higher than in PET bottles), Pb (14×), Al (7×), Zr (7×), Ti, Th (5×), La (5×), Pr, Fe, Zn, Nd, Sn, Cr, Tb (2×), Er, Gd, Bi, Sm, Y, Lu, Yb, Tm, Nb and Cu (1.4×). Testing an additional 136 bottles of the same water sold in green and clear glass bottles demonstrates an important influence of colour, the water sold in green glass shows significantly higher concentrations in Cr (7.3×, 1.0 vs. 0.14 μg/L), Th (1.9×), La, Zr, Nd, Ce (1.6×), Pr, Nb, Ti, Fe (1.3×), Co (1.3×) and Er (1.1×).