Metamorphic ore remobilization in the Hällefors district, Bergslagen, Sweden: constraints from mineralogical and small-scale sulphur isotope studies

Wagner, Thomas; Boyce, Adrian J.

doi:10.1007/s00126-005-0463-2

Cited by 20 publications

(3 citation statements)

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“…The present experiments show that remobilisation could substantially modify the geometry and distribution pattern of syngenetic orebodies, and produce a range of textures characteristic of epigenetic mineralisation, as are noted from many deposits (Vokes & Craig, 1993; Cook, 1996; Gu et al ., 2007). Therefore, to distinguish syngenetic from epigenetic mineralisation, we should remove the late‐stage remobilisation textures, and recover the original features of the ores with the assistance of lead and sulfur isotopes (Wagner et al ., 2005; Gu et al ., 2007).…”

Section: Geological Applicationsmentioning

confidence: 99%

Sulfide Remobilisation from Sulfide Ore at High Temperatures and Differential Stresses: An Experimental Approach

Zheng

Xiaoqian

et al. 2012

Resource Geology

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We conducted experiments to simulate sulfide remobilisation from sulfide ore. The starting material was from the Hongtoushan massive sulfide deposit, NE China, and is composed of pyrite, pyrrhotite, chalcopyrite, sphalerite, quartz, and silicate minerals. The ore was immersed in a solution of 20 wt.% NaCl for 260 h, and then was mounted in a Changjiang 500 triaxial rock stress machine. After the experiments were performed for 13 h at temperatures of 362, 464, 556 and 682°C, with corresponding confining and axial pressures, the samples were cooled at room temperatures. Our results from all the runs indicate that sulfides can be remobilised both mechanically and chemically, and that remobilisation is enhanced at higher temperatures. Mechanical remobilisation can only take place over limited distances and results in minor differentiation between various sulfide minerals. Distant external remobilisation to form new orebodies is most likely caused by chemical remobilisation. In contrast to plastically deformed areas, space resulting from cataclastic deformation could provide conduits for fluid transport and space for metal precipitation. Remobilised iron sulfides will precipitate as pyrrhotite at high temperatures, but as pyrite when temperature decreases. Furthermore, chalcopyrite is more easily remobilised than sphalerite under the conditions of the present experiments. Remobilisation accompanying deformation and metamorphism may add epigenetic features to syngenetic deposits.

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Section: Geological Applicationsmentioning

confidence: 99%

Sulfide Remobilisation from Sulfide Ore at High Temperatures and Differential Stresses: An Experimental Approach

Zheng

Xiaoqian

et al. 2012

Resource Geology

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“…Fahlores related to metamorphic processes have been investigated from Bergslagen, Sweden (Wagner et al, 2005), Boliden, Sweden (Wagner and Jonsson, 2001), Albrunpass, Switzerland-Italy (Klemm et al, 2004) and from Hochtor, Austria (Paar et al, 1978).…”

Section: Comparison To Fahlores From Other Fahlorebearing Localities mentioning

confidence: 99%

“…The fahlore-bearing veins of Bergslagen and Boliden in Sweden are hosted by meta-volcanic rocks and represent metamorphic remobilization products of former massive sulphide deposits, formed between 300 and 400ºC and 350 and 450ºC respectively (Wagner et al, 2005;Wagner and Jonsson, 2001). Mineralization at both localities contain galena, chalcopyrite and Pb-Cu-Sb sulphosalts.…”

Section: Comparison To Fahlores From Other Fahlorebearing Localities mentioning

confidence: 99%

Compositional variation of the tennantite–tetrahedrite solid-solution series in the Schwarzwald ore district (SW Germany): The role of mineralization processes and fluid source

Staude¹,

Mordhorst²,

Neumann³

et al. 2010

Mineral. mag.

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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 is tennantite 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 Ag-bearing 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.

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2011

Economic Geology Principles and Practice

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Metamorphic ore remobilization in the Hällefors district, Bergslagen, Sweden: constraints from mineralogical and small-scale sulphur isotope studies

Cited by 20 publications

References 57 publications

Sulfide Remobilisation from Sulfide Ore at High Temperatures and Differential Stresses: An Experimental Approach

Sulfide Remobilisation from Sulfide Ore at High Temperatures and Differential Stresses: An Experimental Approach

Compositional variation of the tennantite–tetrahedrite solid-solution series in the Schwarzwald ore district (SW Germany): The role of mineralization processes and fluid source

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