Zoltán Zajacz's research while affiliated with University of Geneva and other places

Publications (15)

Article
Full-text available
The Hamburg meteorite fell on January 16, 2018, near Hamburg, Michigan, after a fireball event widely observed in the U.S. Midwest and in Ontario, Canada. Several fragments fell onto frozen surfaces of lakes and, thanks to weather radar data, were recovered days after the fall. The studied rock fragments show no or little signs of terrestrial weath...
Article
Low-dimensional copper halides with high luminance have attracted increasing interest as a heavy-metal free light emitter. However, the optical mechanisms underpinning their excellent luminescence remain underexplored. Here, we report multiple self-trapped emissions in Cs3Cu2I5. Power-dependent photoluminescence spectra reveal the appearance of mul...
Article
Full-text available
Oxygen fugacity (fO2) is a fundamental variable affecting phase equilibrium in magmas, and in externally heated pressure vessel experiments it is typically controlled by using redox buffer assemblages. However, these do not allow fine enough resolution; for example, most arc magmas fall between the fO2 imposed by the neighboring Ni–NiO and Re–ReO2...
Article
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U-Pb ages have been measured on secondary dolomite and silica cements in Cambrian sandstone at the base of an 840 m thick sub-horizontally bedded sedimentary sequence beneath the Bruce nuclear site in southern Ontario to document the history of fluid movement. Results show an average U-Pb age of 320 ± 10 Ma. The initial common Pb end member is slig...
Article
A record of fluid flow has been documented within a Paleozoic carbonate platform sequence by U-Pb dating of calcite in veins and vugs from rock core sampled through a shallowly dipping sequence of sedimentary rocks beneath the Bruce nuclear site, Ontario, Canada. Secondary calcite from >650 m deep Ordovician carbonate rocks yields a Silurian age of...
Article
Silver is a common and economically important constituent of many magmatic-hydrothermal ore deposits, yet little is known about its mobility during magma degassing. We performed experiments to determine the effect of various chemical components (NaCl, KCl, LiCl, HCl, CaCl2, H2S) on the solubility and speciation of Ag in high-temperature, low-densit...
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Full-text available
The solubilities of Pd and Au in a hydrous trachyandesitic melt were experimentally determined at 1000 °C and 200 MPa at oxygen fugacity (ƒO2) from 0.45 log units below to 6.55 log units above the Ni-NiO buffer (NNO). The effect of adding metal-binding ligands (i.e. Cl and S) to the silicate melt was also studied. The solubility of Au increases fro...
Article
Bingham Canyon is one of the world's largest porphyry Cu–Mo–Au deposits and was previously used as an example to emphasize the role of magma mixing and magmatic sulphide saturation in the enhancement of ore fertility of magmatic systems. We analyzed whole rocks, minerals, and silicate melt inclusions (SMI) from the co-genetic, ore-contemporaneous v...
Article
Full-text available
Sulfur is an important volatile element involved in magmatic systems. Its quantification in silicate glasses relies on state-of-the-art techniques such as electronprobe microanalyses (EPMA) or X-ray absorption spectroscopy but is often complicated by the fact that S dissolved in silicate glasses can adopt several oxidation states (S⁶⁺ for sulfates...
Article
The release of large amounts of sulfur to the stratosphere during explosive eruptions affects the radiative balance in the atmosphere and consequentially impacts climate for up to several years after the event. Providing quantitative estimates for the processes that control the mass balance of sulfur between melt, crystals and vapor bubbles is need...
Article
Strong glass/solder/metal seals were prepared between float glass, tin solder and Fe-Ni alloys by the Activated Liquid Tin Solder Anodic Bonding (ALTSAB) process that combines classical anodic bonding with a liquid solder to ensure a near perfect contact between the bonding surfaces. The optimization of the Al content of the solder enables the prod...
Article
Brine and vapor inclusions were synthesized to study Cl/Br fractionation during magmatic–hydrothermal fluid phase separation at 900 °C and pressures of 90, 120, and 150 MPa in Li/Na/K halide salt–H2O systems. Laser ablation ICP-MS microanalysis of high-density brine inclusions show an elevated Cl/Br ratio compared to the coexisting low-density vapo...
Article
The platinum-group elements (PGEs; Os, Ir, Ru, Rh, Pt, Pd), along with rhenium and gold, are grouped together as the highly siderophile elements (HSEs), defined by their extreme partitioning into the metallic, relative to the oxide phase (> 104). The HSEs are highly refractory, as gauged by their high melting and condensation temperatures, and were...

Citations

... Meteorites offer unique insights into the chronology of our Solar System, as well as a fundamental understanding as to how planetary bodies formed and evolved (e.g., Anders, 1971;Lauretta and McSween, 2006;Day, 2015). The study of chondrite meteorites has provided the foundations for understanding the constituent materials supplied to the Solar System, as well as the building blocks for planet formation (e.g., Anders and Grevesse, 1989;McDonough and Sun, 1995;Righter and Drake, 1997;Warren, 2011;Heck et al., 2020). In particular, studies of the highly siderophile elements (HSE: Os, Ir, Ru, Rh, Pt, Pd, Re, Au) and Os isotopic variations in chondrites carry information on the materials involved in the formation of the Solar System (e.g., Brandon et al., 2005a,b;Yokoyama and Walker, 2016), condensation processes inherent in the early solar nebula (Palme and Wlotzka, 1976), and the bulk compositional variations in chondrites and their components (e.g., Walker et al., 2002;Horan et al., 2003;Fischer-Gö dde et al., 2010;Archer et al., 2014). ...
... Some efforts have been devoted to the synthesis of lead-free metal halides with broad-band emission covering the entire visible spectral range, which can be ascribed to selftrap excitations (STEs). For example, blue-emitting Cs 3 Cu 2 I 5 are recently well-studied by several research groups [27][28][29][30][31], exhibiting a photoluminescence (PL) peak at 440 nm and high PL QYs of over 90% [31]. Kovalenko et al. reported a green Cs 4 SnBr 6 with an emission peak of 540 nm [32]. ...
... To simulate these processes in laboratories, several well established redox control techniques have been applied in hydrothermal experiments, including the double capsule (or oxygen buffer) (Eugster, 1957) and Shaw membrane techniques (Shaw, 1963). However, even after considerable refinements in the past six decades (Chou, 1987;Taylor et al., 1992;Berndt et al., 2002;Matthews et al., 2003;Alex and Zajacz, 2020), these techniques cannot be applied at low temperatures (T < 400°C) because the precious metal hydrogen membranes that are commonly used in these techniques, such as Pt or Ag-Pd alloys, are not effective at these Ts (Chou, 1986). ...
... Recent developments in the elemental analysis of individual uid inclusions by LA-ICP-MS were summarised 286 in a short review (68 references) in which strategies for improving the success rate of ablation, accurate quantication and selection of suitable uid inclusions were discussed. Tuba et al. 287 addressed the problem of analysing assemblages of uid inclusions in orogenic gold deposits in which the inclusions are oen too small and densely populated to be measured individually by LA-ICP-MS. For this application, inclusion-rich areas of the quartz host were analysed using a single continuous LA prole. ...
... In situ laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) dating of calcite has recently been established as an absolute dating method that has been successfully applied for constraining syn-to postsedimentary diagenesis and burial processes (Mangenot et al., 2018;Pagel et al., 2018), fluid migration in sedimentary basins Sutcliffe et al., 2020), brittle deformation events (Roberts and Walker, 2016;Beaudoin et al., 2018;Parrish et al., 2018;Mottram et al., 2020), and ocean crust alteration (Coogan et al., 2016). Application to ore-forming processes is still in its infancy, but several studies have already demonstrated the potential of in situ U-Pb geochronology on calcite for investigating the chronology of ore-forming events (Burisch et al., 2017;Kreissl et al., 2018). ...
... The flow pathways of paleo-waters through fractures and intergranular pores are essential to document as they provide analogies with potential ways of migration of radionuclides. The geochemistry and distribution of calcite cements also help to unravel tectonic evolution (André et al., 2010), and in some instances, to date brittle deformation (Goodfellow et al., 2017;Pagel et al., 2018;Mazurek et al., 2018;Sutcliffe et al., 2020;Davis et al., 2020). Finally, the study of paleo-circulations and their effects on hydrologic properties help to better understand present-day aquifer features (Carpentier et al., 2015;Brigaud et al., 2009a). ...
... It is clear that neither the tolerance factor nor the method underlying SPuDS can completely take into account all these factors. Therefore, in recent years, researchers have paid attention to the methods of machine learning, which makes it possible to find complex regularities linking the properties of perovskites with the parameters of chemical elements that compose the compound on the basis of the analysis of information concerning already known A 2 BB'O 6 compounds [19][20][21][22][23][24][25]. ...
... The key constituents for their genesis, ore metals and S, are both supplied by magma-derived aqueous fluids 1 . Furthermore, the transport of many ore metals is tied to the availability of Cl as a ligand, with which they form aqueous complexes [2][3][4] . Nevertheless, the budget of ore metals, S and Cl in arc magmas is poorly constrained. ...
... In the case of Au, numerous studies found that the variation of the solubility of Au in silicate melts as a function of fO 2 is consistent with Au being present in + 1 oxidation state in the silicate melt Jégo et al., 2010;Bell et al., 2011;Zajacz et al., 2012b;Sullivan et al., 2018). Our study confirms that Au exists in + 1 oxidation state across the fO 2 range relevant for arc magmatism. ...
... In contrast to other volcanoes, glassy SMI were very rare or absent in the Maipo samples. To enable the determination of Cl concentrations in SMI from Maipo, we experimentally homogenized originally crystallized SMI to glasses suitable for measurement by EPMA following the method of ref. 71 at 1030°C and 0.2 GPa for 1.5 h prior to quenching. Homogenized SMI were identified following sectioning, mounting, and polishing of the heated cores. ...