The use of mantle normalization and metal ratios in the identification of the sources of platinum-group elements in various metal-rich black shales

It has been shown that Ni/Cu versus Pd/Ir and Cu/Ir versus Ni/Pd ratios, as well as mantle-normalized metal patterns can be successfully used to evaluate the effects of partial melting, crystal fractionation and sulfide saturation in mafic and ultramafic rocks. Platinum-group element (PGE) enrichments occur in Zn-, Cu- and Ni-rich black shales in a number of geological settings. These facies are generally associated with the development of continental rift structures, both without significant volcanic activity (examples in Canada, China, Finland and Poland) and with volcanic activity (Czech Republic and Namibia). Using the same element ratios as were used in mafic igneous rocks, it is evident that metal-rich black shales associated with volcanic rocks reflect the fractionation of PGEs in volcanogenic facies. It is further concluded that, in metal-rich black shales in which distributions of Ni and Cu have been altered by various processes, the Cu/Ir versus Ni/Pd and Ni/Cu versus Pd/Ir ratios plots are applicable for determination of the source of PGEs only after careful evaluation of Ni and Cu enrichments

Lead fluxes and 206Pb/207Pb isotope ratios in rime and snow collected at remote mountain-top locations (Czech Republic, Central Europe): Patterns and sources

During three winter seasons (2009-2011), Pb concentrations were measured in precipitation at 10 high-elevation sites in the Czech Republic, close to the borders with Austria, Germany, Poland, and Slovakia. Soluble and insoluble Pb forms were quantified in snow (vertical deposition), and rime (horizontal deposition). The objective was to compare Pb input fluxes into ecosystems via vertical and horizontal deposition, and to identify the residual Pb polution sources in an era of rapidly decreasing industrial pollution. Lead soluble in diluted HNO3 made up 96 % of total Pb deposition, with the remaining 4 % Pb bound mainly in silicates. Four times higher concentrations of soluble Pb in rime than in snow, and 1.6 times higher concentrations of insoluble Pb in rime than in snow were associated with slightly different Pb isotope ratios. On average, the 206Pb/207Pb ratios in rime were higher than those in snow. Higher 206Pb/207Pb ratios of insoluble Pb than in insoluble Pb may indicate an increasing role of geogenic Pb in recent atmospheric deposition. A distinct reversal to more radiogenic 206Pb/207Pb ratios in snow and rime in 2010, compared to literature data from rain-fed Shagnum peatlands (1800-2000 A.D.), documented a recent decrease in anthropogenic Pb in the atmosphere of Central Europe. Since the early 1980s, Pb concentrations in snow decreased 18 times in the rural south of the Czech Republic, but only twice in the industrial north of the Czech Republic. Isotope signatures indicated that Pb in today’s atmospheric deposition is mainly derived from Mesozoic ores mined/processed in southern Poland and coal combustion in the Czech Republic and Poland.JRC.G.II.6-Nuclear Safeguards and Forensic

Global catastrophes in earth history: an interdiciplinary conference on impacts, volcanism, and mass mortality.

Topics addressed include Cretaceous-Tertiary mass extinctions; geological indicators for meteorite collisions; carbon dioxide catastrophes; volcanism; climatic changes; geochemistry; mineralogy; fossil records; biospheric traumas; stratigraphy; mathematical models; and ocean dynamics

Common Occurrence of a Positive δ⁵³Cr Shift in Central European Waters Contaminated by Geogenic/Industrial Chromium Relative to Source Values

Carcinogenic effects of hexavalent chromium in waters are of concern in many countries worldwide. We explored Cr isotope systematics at 11 sites in the Czech Republic and Poland. Geogenic Cr pollution was associated with serpentinite bodies at former convergent plate margins, while anthropogenic Cr pollution resulted from electroplating, tanning, and the chemical industry. Cr­(VI) concentration in geogenic waters was less than 40 ppb. Anthropogenic waters contained up to 127,000 ppb Cr­(VI). At both geogenic and anthropogenic sites, where known, the source of pollution had a low δ⁵³Cr (<1‰). δ⁵³Cr of geogenic and anthropogenic waters was up to 3.9 and 5.8‰, respectively. At both serpentinite-dominated and industrial sites, δ⁵³Cr­(VI)_aq was shifted toward higher values, compared to the pollution source. At the industrial sites, this positive δ⁵³Cr shift was related to Cr­(VI) reduction, a process known to fractionate Cr isotopes. At geogenic sites, the origin of high δ⁵³Cr­(VI)_aq is tentatively ascribed to preferential release of ⁵³Cr during oxidation of soil Cr­(III) and its mobilization to water. δ⁵³Cr­(VI) of industrially contaminated waters was significantly higher (<i>p</i> < 0.001) compared to δ⁵³Cr of waters carrying geogenic Cr­(VI), implying that either the effective fractionation factor or process extent was greater for Cr­(VI) reduction than for Cr­(III) oxidation