Episodic mineralization of hydrothermal illite in the Soultz-sous-Forêts granite (Upper Rhine Graben, France)

Schleicher, Anja M.; Warr, Laurence N.; Kober, Bernd; Laverret, Emmanuel; Clauer, Norbert

doi:10.1007/s00410-006-0110-7

Cited by 50 publications

(22 citation statements)

References 41 publications

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“…TEM images of the finest (\0.1 lm) clay fractions show that the dated K-bearing illite/muscovite grains have a pseudohexagonal platelet form (Fig. 5b) typical of the 2M 1 polytype (Inoue et al 1988;Schleicher et al 2006), confirming the quantitative XRD results that 2M 1 is the only polytype present. The idiomorphic morphology of some of these very fine grains (Fig.…”

Section: Discussionsupporting

confidence: 72%

“…Velde 1965;Schleicher et al 2006). The observed idiomorphic grain boundaries in the finest analysed fractions with typical 2M 1 pseudohexagonal platelet forms (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…WR (''whole rock'') refers to the field sample as collected, without size fraction separation evolution to the higher temperature 2M 1 polytype (Inoue et al 1988;Clauer and Chaudhuri 1995;Bauer et al 2000;Clauer et al 2014). Schleicher et al (2006) also observed that, in a hydrothermally altered granite, authigenic 2M 1 illite in vein fillings had a platy pseudohexagonal form, whereas 1M illite filling pores was fibrous. The morphology of the finest clay particles (Fig.…”

Section: Sem and Tem Observations On Clay Morphologymentioning

confidence: 99%

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Timing and conditions of brittle faulting on the Silltal-Brenner Fault Zone, Eastern Alps (Austria)

et al. 2015

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The Silltal Fault is the northern brittle continuation of the Brenner Fault Zone, marked by a narrow zone of cataclasis and, in three locations, clay-rich fault gouges. The clay mineral composition of these gouges is dominated by higher temperature 2M 1 polytype illite/muscovite, with no 1M/1M d illite or mixed layer illite/ smectite detected. Smectite is limited to the northern samples from the Stephansbrücke location, whereas chlorite is present in all samples. The K-Ar ages from the different sample size fractions (\0.1, \0.4, \2, 2-6, 6-10 lm, ''whole rock gouge'') show a wide spread, from ca. 115 to 12 Ma, with ages consistently decreasing with grain size. Although the ranges overlap, ages from the northern Stephansbrücke samples are generally older (115-36 Ma) than those from the south near Matrei (55-12 Ma), possibly reflecting increasing regional metamorphic temperatures to the south. The well-defined linear relationship between apparent age and hydrogen stable isotope (dD) values establishes a direct correlation between rejuvenation of the K-Ar system and increased interaction with meteoric water introduced and focussed within the fault zone. The dependence of both apparent age and dD on grain size also indicates that radiogenic and stable isotope exchange was controlled by grain size, reflecting new 2M 1 illite growth, mechanical grinding of protolith muscovite during cataclastic faulting, or both. The results demonstrate the advantages of combining radiogenic and stable isotope analysis in interpretation of K-Ar ages from clay fault gouges. The combined approach was necessary to establish the crucial influence on apparent K-Ar ages of meteoric water influx focussed on the fault zone and its interaction with clay-size-fraction grains.

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Section: Discussionsupporting

confidence: 72%

“…Velde 1965;Schleicher et al 2006). The observed idiomorphic grain boundaries in the finest analysed fractions with typical 2M 1 pseudohexagonal platelet forms (Fig.…”

Section: Discussionmentioning

confidence: 99%

Section: Sem and Tem Observations On Clay Morphologymentioning

confidence: 99%

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Timing and conditions of brittle faulting on the Silltal-Brenner Fault Zone, Eastern Alps (Austria)

et al. 2015

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“…The than a pressure effect (e.g., Sassi and Scolari, 1974;Guidotti and Sassi, 1986 (Shirozu and Higashi, 1972;Meunier and Velde, 1982;Inoue et al, 1987Inoue et al, , 1988Drits et al, 1993;Inoue and Kitagawa, 1994;Drews-Armitage et al, 1996;Celik et al, 1999;Yan et al, 2001;Bove et al, 2002;Schleicher, 2006).…”

Section: Mineralogymentioning

confidence: 99%

Illite occurrences related to volcanic-hosted hydrothermal mineralization in the Biga Peninsula, NW Turkey: Implications for the age and origin of fluids

Bozkaya

Uysal

et al. 2016

Ore Geology Reviews

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“…Here, primary silicates, such as feldspar and biotite, were transformed into clay minerals, with the original texture of the granite being destroyed by shearing. The precipitation in veins contains secondary quartz, barite, illite, carbonates, iron oxides, and, locally, mixed-layers of illite-smectite and chlorite-smectite (Genter et al 2000;Schleicher et al 2006). In some altered zones, quartz, biotite, plagioclase, and hornblende are dissolved completely (Ledésert et al 2010).…”

Section: Egs Reference Soultz-sous-forêtsmentioning

confidence: 99%

Criteria and geological setting for the generic geothermal underground research laboratory, GEOLAB

et al. 2016

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High flow rate injection and related hydromechanical interaction are the most important factors in reservoir development of Enhanced Geothermal Systems (EGS). GeoLaB, a new generic geothermal underground research laboratory (URL), is proposed for controlled high flow rate experiments (CHFE) to address limited comprehension of coupled processes connected to EGS reservoir flow conditions. As analogue for typical EGS development, CHFE require specific hydromechanical conditions including a connected fracture network in crystalline basement rock, sufficient hydraulic fracture transmissivities, a strike-slip to normal faulting tectonic regime, controllable hydraulic boundary conditions, and hydrothermal alteration fracture fillings that improve conditions for hydromechanical interaction. With the aim to identify most appropriate areas for future site selection, four criteria have been established based on the EGS reference site of Soultz. Two URLs in crystalline basement worldwide approximate the requirements of a new generic GeoLaB and may be used for accompanying experimentation. Besides favourable geological, hydraulic, and stress conditions, the vicinity to long-term EGS production favours the southern Black Forest as potential region for GeoLaB. Therefore, an exemplary site assessment has been carried out at "Wilhelminenstollen" in the southern Black Forest (Germany). New remote sensing, hydrochemical, and geophysical analyses as well as reactivation potential, and stress modelling were added to complement existing geological and hydrogeological information. At this site, reactivation potential analysis reveals two local maxima prone for shear reactivation as strike-slip faults. The highest lineament density is observed for the N110°E strike direction that is associated with both slip and dilation tendency maxima. Clay minerals occur in fractures and the matrix. Local, partly water-bearing fractures, when partly filled with ore minerals, were connected to veins in the tunnel using shallow geophysical methods. Hydrochemical data reveal infiltration of the tunnel water from at least 500 m above the tunnel. The results suggest a crystalline basement with a fracture network that is regionally connected and water-conducting. Hydraulic conductivity in the southern Black Forest granite is estimated to amount to about 4.5·10 −8 m s −1 at 500 m depth. The hydraulic boundary conditions exclude unknown drainage. Analyses of the influence of topography on orientation and magnitude of the maximum stress indicate a minimum overburden of about 500 m for regional reactivation to be valid. In conclusion, the southern Black Forest and in particular "Wilhelminenstollen" offers favourable condition for CHFE. Final decision on the GeoLaB site is to be drawn from forthcoming exploration wells.

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Episodic mineralization of hydrothermal illite in the Soultz-sous-Forêts granite (Upper Rhine Graben, France)

Cited by 50 publications

References 41 publications

Timing and conditions of brittle faulting on the Silltal-Brenner Fault Zone, Eastern Alps (Austria)

Timing and conditions of brittle faulting on the Silltal-Brenner Fault Zone, Eastern Alps (Austria)

Illite occurrences related to volcanic-hosted hydrothermal mineralization in the Biga Peninsula, NW Turkey: Implications for the age and origin of fluids

Criteria and geological setting for the generic geothermal underground research laboratory, GEOLAB

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