Sebastian Staude
University of Tübingen
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Publication
Featured researches published by Sebastian Staude.
Mineralogical Magazine | 2010
Sebastian Staude; Teresa Mordhorst; R. Neumann; W. Prebeck; Gregor Markl
Abstract The study presents analysis from members of the tennantite−tetrahedrite solid-solution series (‘fahlore’) from 78 locations in the Schwarzwald ore district of SW Germany. Electron microprobe analysis is used to correlate the compositional variations of the fahlores with mineral association, host rock, tectonic history and precipitation mechanisms. Results indicate that most fahlores from gneiss-hosted veins do not have distinctive geochemical characteristics and range from tetrahedrite to tennantite end-member composition with variable trace-element content. However, diagenetically formed fahlore has a near-end-member tennantite composition with very small trace-element content. Red-bed-hosted fahlore formed by fluid mixing istennantite enriched in Hg that probably has its source in the red-bed sediments. Fahlore formed from granite-related late-magmatic fluids, or from mixing of fluids of which one has equilibrated with granitic basement rocks, is typically As- and Bi-rich (up to 22.2 wt.% Bi). Gneiss-hosted fahlore formed by fluid cooling is Ag-rich near-end-member tetrahedrite. Some fahlores reflect their paragenetic association, e.g. a large Ag content in association with Agbearing minerals or a large Co and Ni in association with Co- and Ni-arsenides. Although they have similar compositions, gneiss-hosted fahlores show systematic variations in Ag contents and Fe/Zn ratios between the Central and the Southern Schwarzwald with Fe-rich fahlore in higher stratigraphic levels (North) and Zn- and Ag-rich fahlore in lower stratigraphic levels (South). We show that fahlore composition varies with precipitation mechanism (cooling vs. mixing vs. diagenesis), depth of formation, paragenetic association and host rock. Comparison with fahlores from other European occurrences indicates that these conclusions are consistent with fahlore systematics found elsewhere, and could be used to infer details of ore-forming processes.
Geology | 2016
Sebastian Staude; Stephen J. Barnes; Margaux Le Vaillant
The Fe-Ni-Cu sulfide ores at Kambalda, Western Australia, are interpreted to be the result of thermomechanical erosion of underlying rocks by the host komatiite lava flows. However, there is a long-standing argument about the extent of the erosion process, and the degree to which the linear embayments that host the ores were eroded by lava as opposed to formed by tectonic processes. This controversy has fundamental implications for the origin of magmatic sulfide ore, as well as for sinuous rilles on terrestrial planets. The controversy at Kambalda hinges on pinchout features, where sulfide ore at the edges of embayments penetrates laterally into footwall rocks. The most recently published studies of these features interpret them as forming by thrusting of basalts over sulfide-komatiite contacts along the margins of tectonic embayments. Field evidence and X-ray fluorescence element mapping on underground exposures in the Moran deposit demonstrate that sulfide liquid melted its way both downward and laterally into basalt, generating complex plumose melt layers, melt emulsions, and hybridized chromite-decorated contacts. These observations confirm an origin for the pinchouts by thermomechanical erosion, driven by the high temperature, high density, and low viscosity of the sulfide melt. They also provide some intriguing insights into the nature of interactions between sulfide melt and melting silicate rocks in magmatic Ni-Cu-platinum group element sulfide ore deposits in general.
American Mineralogist | 2012
Katharina Pfaff; Sebastian Staude; Gregor Markl
Abstract Sellaite (MgF2) forms from melts, fluids, and gases under variable temperature, pressure, fO₂, and fluid salinity conditions. It is typically associated with, but much rarer, than fluorite (CaF2). The Clara mine near Oberwolfach (Schwarzwald, Germany) is an extensive hydrothermal vein-type deposit, where sellaite occurs in huge quantities (thousands of tons) in veins of mostly Jurassic/Cretaceous age. The sellaite mineralization, occurring in gneisses altered prior to and during sellaite mineralization, represents a stockwork-like network of veins and fissures, which is overlain and sealed by sediments, preventing the inflow of and fluid-mixing with sedimentary formation waters. The occurrence of sellaite is unique among the more than 1000 hydrothermal vein-type occurrences of the Schwarzwald ore district. The favored formation of sellaite compared to fluorite requires the initial Ca/Mg-ratio of the mineralizing fluid to be unusually low. These conditions are possible if fluids equilibrate with pre-altered rocks that lost some or much of their Ca during an earlier hydrothermal alteration event. Indeed, calculations demonstrate that rock-buffered fluids of pre-altered rocks (i.e., gneiss around the Clara mine altered during prior hydrothermal events) show significantly lower Ca/Mg-ratios than fluids equilibrated with unaltered gneisses, because Ca-phases (e.g., the anorthite component of plagioclase) are more prone to hydrothermal destruction. Due to the network-like structure of the sellaite-bearing portion of the Clara fluorite vein, the fluid is shielded from sedimentary formation water, resulting in fractionation processes of the repeatedly ascending mineralizing fluid. In addition, fluid cooling and formation of water-bearing phases like illite that consume fluids, favor sellaite, and later fluorite precipitation. The rarity of this combination of prerequisites explains the limited occurrence of sellaite in hydrothermal vein-type deposits.
Canadian Mineralogist | 2007
Sebastian Staude; Thomas Wagner; Gregor Markl
Mineralium Deposita | 2012
Sebastian Staude; Wolfgang Werner; Teresa Mordhorst; Klaus Wemmer; Dorrit E. Jacob; Gregor Markl
Chemical Geology | 2011
Sebastian Staude; Susanne Göb; Katharina Pfaff; Florian Ströbele; Wayne R. Premo; Gregor Markl
Canadian Mineralogist | 2010
Sebastian Staude; Alevtina Dorn; Katharina Pfaff; Gregor Markl
Chemical Geology | 2010
Martin Danišík; Katharina Pfaff; Noreen J. Evans; Christos Manoloukos; Sebastian Staude; Brad J. McDonald; Gregor Markl
Canadian Mineralogist | 2012
Sebastian Staude; Teresa Mordhorst; Sarah Nau; Katharina Pfaff; Gerhard Brügmann; Dorrit E. Jacob; Gregor Markl
Ore Geology Reviews | 2017
Sebastian Staude; Stephen J. Barnes; Margaux Le Vaillant
Collaboration
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Commonwealth Scientific and Industrial Research Organisation
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