Complex hydrothermal alteration and illite K–Ar ages in Upper Visean molasse sediments and magmatic rocks of the Variscan Badenweiler-Lenzkirch suture zone, Black Forest, Germany

Brockamp, Olaf; Schlegel, Andreas; Wemmer, Klaus

doi:10.1007/s00531-014-1118-2

Cited by 14 publications

(15 citation statements)

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“…However, the very distinct vertical zonality of altered illite in the coals (Figures 11 and 12) is worthy of further study. Some studies have shown that, in medium-low temperature hydrothermal altered environments, illite generally forms by illitization of plagioclase and mica, and is mainly affected by fluid influx, water/rock ratio, temperature, and potassium contents in fluids [75][76][77]. The very distinct vertical zonality of illitization and chloritization in the coals (Figure 11) seems to indicate that limited fluid influx or a low water/rock ratio during water-rock interactions between magmatic hydrothermal fluids and coals might have restricted the formation of altered illite in upper 12U Coal, which can also be inferred from the decreasing percentage of K 2 O through the vertical distribution of the coal (Figure 11).…”

Section: Favorable Conditions For the Enrichment Of W Rb And Cs In mentioning

confidence: 99%

Minerals and Enrichment of W, Rb, and Cs in Late Permian Coal from Meitian Mine, Meitian Coalfield, Southern China by Magmatic Hydrothermal Fluids

et al. 2018

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We report on the effects of magmatic hydrothermal fluids on the mineralogical and geochemical compositions of 12U and 12L Coals from the Meitian Mine in the Meitian Coalfield, southern China. The minerals in 12U Coal are predominantly chlorite, quartz, and calcite, while the minerals in 12L Coal consist mainly of illite, quartz, chlorite, kaolinite, and mixed-layer illite/smectite (I/S). The vesicle- and fracture-filling illite, chlorite, I/S, pyrite, and fluorite, cleat- and fracture-filling carbonate minerals (i.e., calcite, and dolomite), and cleat-filling tremolite, diopside, and talc have epigenetic hydrothermal origins. Tremolite, diopside, and talc were probably formed from the reaction between dolomite and Si-rich magmatic hydrothermal fluids. Elevated Pb–Zn–Sn–Cd assemblages are characteristic for the 12U Coal, while 12L Coal is enriched in W, Rb, Cs, Th, V, Zn, and Zr, most notably W, Rb, and Cs. REY (Rare Earth Elements and Yttrium) plots for almost all coals, partings and host rocks are similar, showing an M-type REY distribution, Gd-maximum, positive Y anomalies, and negative Ce anomalies, suggesting acid hydrothermal circulation in the coal-bearing strata. Rubidium and cesium in the coal is clearly associated with K-rich clay minerals (illite + I/S), and to a lesser extent with silicate minerals that were precipitated from hydrothermal solutions. W in the coals mainly occurs in the inorganic constituents of illite and pyrite, especially illite. Enrichment of W, Rb, and Cs in the coal and host rocks is genetically associated with magmatic hydrothermal fluids. Specifically, magmatic hydrothermal fluids of relatively high temperatures that are rich in volatile matter can extract abundant W, Rb, and Cs from granitic melts. The enrichment of these rare metals in the coal is mainly related to illitization. Our study results suggest that, for coal intruded by magmatic rocks, the type of hydrothermal alteration may greatly influence the enrichment of elements.

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Section: Favorable Conditions For the Enrichment Of W Rb And Cs In mentioning

confidence: 99%

Minerals and Enrichment of W, Rb, and Cs in Late Permian Coal from Meitian Mine, Meitian Coalfield, Southern China by Magmatic Hydrothermal Fluids

et al. 2018

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“…In the Black Forest, alteration often resembles clay mineral assemblage at the Soultz site. For example, 60-90 wt% of illite, smectite, and chlorite are observed in altered granitic rocks of the southern Black Forest batholith (Brockamp et al 2015).…”

Section: Urls Existing In the Crystalline Basementmentioning

confidence: 99%

“…2) Appropriate hydrothermal alteration is widely observed in the Black Forest (Brockamp et al 2015). 3) Extended fracture networks are indicated (Stober and Bucher 2014).…”

Section: Urls Existing In the Crystalline Basementmentioning

confidence: 99%

“…Bons et al 2014). Radiometric dating of minerals originating from hydrothermal alteration of crystalline basement rocks and Permo-Triassic cover rock successions as well as of minerals originating from fault-related, mineralised veins reveal multiple and complex postVariscan phases of pervasive and localised fluid-rock interactions (Brockamp et al 2015;Zuther and Brockamp 1988;Glodny and Grauert 2009). …”

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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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“…In the Badenweiler-Lenzkirch zone,a lteration with 60-90 wt %o fi llite,c hlorite, and kaolinite [19] resembles the clay mineral assemblage at the Soultz site.Att he Lindaut est site, only kaoliniteo ccurs.I nterestingly,c lay minerals occur preferablyi nN W-SE strikingf ractures (Himmelsbach, personal communication).…”

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confidence: 99%

Integrated Research as Key to the Development of a Sustainable Geothermal Energy Technology

et al. 2017

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As estimated by the International Energy Agency, geothermal power can contribute to 3.5 % of worldwide power and 3.9 % to heat production by 2050. This includes the development of enhanced geothermal systems (EGSs) in low‐enthalpy systems. EGS technology is still in an early stage of development. Pushing EGS technologies towards market maturity requires a long‐term strategic approach and massive investments in research and development. Comprehensive multidisciplinary research programs that combine fundamental and applied concepts to tackle technological, economic, ecological, and safety challenges along the EGS process chain are needed. The Karlsruhe Institute of Technology (KIT) has defined a broad research program on EGS technology development following the necessity of a transdisciplinary approach. The research concept is embedded in the national research program of the Helmholtz Association and is structured in four clusters: reservoir characterization and engineering, thermal water circuit, materials and geoprocesses, and power plant operation. The proximity to industry, closely interlinked with fundamental research, forms the basis of a target‐orientated concept. The present paper aims to give an overview of geothermal research at KIT and emphasizes the need for concerted research efforts at the international level to accelerate technological breakthrough of EGS as an essential part of a future sustainable energy system.

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Complex hydrothermal alteration and illite K–Ar ages in Upper Visean molasse sediments and magmatic rocks of the Variscan Badenweiler-Lenzkirch suture zone, Black Forest, Germany

Cited by 14 publications

References 36 publications

Minerals and Enrichment of W, Rb, and Cs in Late Permian Coal from Meitian Mine, Meitian Coalfield, Southern China by Magmatic Hydrothermal Fluids

Minerals and Enrichment of W, Rb, and Cs in Late Permian Coal from Meitian Mine, Meitian Coalfield, Southern China by Magmatic Hydrothermal Fluids

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

Integrated Research as Key to the Development of a Sustainable Geothermal Energy Technology

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