Sulfur isotope variations from orebody to hand-specimen scale at the Mezica lead-zinc deposit, Slovenia: a predominantly biogenic pattern

The Mississippi Valley-type (MVT) Pb-Zn ore district at Mezica is hosted by Middle to Upper Triassic platform carbonate rocks in the Northern Karavanke/Drau Range geotectonic units of the Eastern Alps, northeastern Slovenia. The mineralization at Mezica covers an area of 64 km(2) with more than 350 orebodies and numerous galena and sphalerite occurrences, which formed epigenetically, both conformable and discordant to bedding. While knowledge on the style of mineralization has grown considerably, the origin of discordant mineralization is still debated. Sulfur stable isotope analyses of 149 sulfide samples from the different types of orebodies provide new insights on the genesis of these mineralizations and their relationship. Over the whole mining district, sphalerite and galena have delta(34)S values in the range of -24.7 to -1.5% VCDT (-13.5 +/- 5.0%) and -24.7 to -1.4% (-10.7 +/- 5.9%), respectively. These values are in the range of the main MVT deposits of the Drau Range. All sulfide delta(34)S values are negative within a broad range, with delta(34)S(pyrite) < delta(34)S(sphalerite) < delta(34)S(galena) for both conformable and discordant orebodies, indicating isotopically heterogeneous H(2)S in the ore-forming fluids and precipitation of the sulfides at thermodynamic disequilibrium. This clearly supports that the main sulfide sulfur originates from bacterially mediated reduction (BSR) of Middle to Upper Triassic seawater sulfate or evaporite sulfate. Thermochemical sulfate reduction (TSR) by organic compounds contributed a minor amount of (34)S-enriched H(2)S to the ore fluid. The variations of delta(34)S values of galena and coarse-grained sphalerite at orefield scale are generally larger than the differences observed in single hand specimens. The progressively more negative delta(34)S values with time along the different sphalerite generations are consistent with mixing of different H(2)S sources, with a decreasing contribution of H(2)S from regional TSR, and an increase from a local H(2)S reservoir produced by BSR (i.e., sedimentary biogenic pyrite, organo-sulfur compounds). Galena in discordant ore (-11.9 to -1.7%; -7.0 +/- 2.7%, n=12) tends to be depleted in (34)S compared with conformable ore (-24.7 to -2.8%, -11.7 +/- 6.2%, n=39). A similar trend is observed from fine-crystalline sphalerite I to coarse open-space filling sphalerite II. Some variation of the sulfide delta(34)S values is attributed to the inherent variability of bacterial sulfate reduction, including metabolic recycling in a locally partially closed system and contribution of H(2)S from hydrolysis of biogenic pyrite and thermal cracking of organo-sulfur compounds. The results suggest that the conformable orebodies originated by mixing of hydrothermal saline metal-rich fluid with H(2)S-rich pore waters during late burial diagenesis, while the discordant orebodies formed by mobilization of the earlier conformable mineralization

Geschichte des Lehrerinnen- und Lehrerberufs

Der Beitrag thematisiert die Geschichte des Lehrberufs im Kontext von Verstaatlichungsprozessen und des Ausbaus von Wissen(schafts)systemen. Anhand von drei Länderbeispielen (Deutschland, Schweiz und Österreich) werden die Entwicklungen nachgezeichnet, um abschließend einige charakteristische Merkmale und neuralgische Punkte auszuarbeiten

Vertical density gradient in the eastern North Atlantic during the last 30,000 years

Past changes in the density and momentum structure of oceanic circulation are an important aspect of changes in the Atlantic Meridional Overturning Circulation and consequently climate. However, very little is known about past changes in the vertical density structure of the ocean, even very extensively studied systems such as the North Atlantic. Here we exploit the physical controls on the settling depth of the dense Mediterranean water plume derived from the Strait of Gibraltar to obtain the first robust, observations-based, probabilistic reconstruction of the vertical density gradient in the eastern North Atlantic during the last 30,000 years. We find that this gradient was weakened by more than 50%, relative to the present, during the last Glacial Maximum, and that changes in general are associated with reductions in AMOC intensity. However, we find only a small change during Heinrich Event 1 relative to the Last Glacial Maximum, despite strong evidence that overturning was substantially altered. This implies that millennial-scale changes may not be reflected in vertical density structure of the ocean, which may be limited to responses on an ocean-overturning timescale or longer. Regardless, our novel reconstruction of Atlantic density structure can be used as the basis for a dynamical measure for validation of model-based AMOC reconstructions. In addition, our general approach is transferrable to other marginal sea outflow plumes, to provide estimates of oceanic vertical density gradients in other locations

Relax sports facility with accommodation

Předmětem této diplomové práce je projektová dokumentace Relaxačně sportovního objektu s ubytováním v Suchdole nad Odrou. Polyfunkční dům je třípodlažní a částečně podsklepený, zastřešení je po celém objektu plochou jednoplášťovou střechou. Z materiálového hlediska je podsklepená část vyzděna z tvarovek ztraceného bednění, všechny nadzemní podlaží jsou zděny z pálených cihelných bloků. Fasáda je řešena jako provětrávaná. Stropní konstrukce budou z ŽB monolitické desky a sportoviště je zastřešeno pomocí lepených lamelových nosníků. Podsklepená část objektu je relaxační – zde se nachází různé typy saun, ochlazovna, Whirlpool a masážní místnost. V prvním nadzemním podlaží je orientována restaurace se zázemím a kuchyní, kavárna, a sportovní vyžití v podobě badmintonu, squashe a posilovny. Další 2 nadzemní podlaží slouží výhradně k ubytování hostů v hotelu. Všechny provozy jsou spolu funkčně propojeny přes recepční halu.The Subject of this diploma thesis is design documentation of Relax sports facility with accommodation in Suchdol and Odrou. Mixed-use building is three-storeyed with partial basement. Roofing is flat single-skinned roof over the entire building. From the material point of view, the basement is made from lost formwork, all aboveground floors are bricked from ceramic blocks. The facade is designed as ventilated. Ceilings will be made from cast-in-place reinforced slabs and the sports ground will be covered with glued lamellar beams. The basement part of the building is relaxing - there are various types of saunas, cooler, whirlpool and massage room. On the first floor there is a restaurant with backgrounds and kitchen, a café, and sports activities in the form of badminton, squash and gym. Two more floors are used mainly to accommodate guests in the hotel. All operations are functionally connected by the reception hall.