The Geological Framework of the KTB Drill Site, Oberpfalz

Franke, Wolfgang

doi:10.1007/978-3-642-74588-1_3

Cited by 43 publications

(19 citation statements)

References 23 publications

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“…Two research boreholes were drilled into the Variscan basement at Oberpfalz, Bavaria, in the Zone of ErbendorfVohenstrauB (ZEV) (Franke 1989;Kontny et al 1997). A pilot hole, the KTB-VB, went to about 4 km deep, and a subsequent superdeep main hole, the KTB-HB, went to about 9.1 km deep; the two boreholes were about 200 m apart (Emmermann and Lauterjung 1997).…”

Section: Ktb-borehole Anomaly Germanymentioning

confidence: 99%

Tracing of paleo-shear zones by self-potential data inversion: case studies from the KTB, Rittsteig, and Grossensees graphite-bearing fault planes

Mehanee

2015

Earth Planets Space

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This paper describes a new method for tracing paleo-shear zones of the continental crust by self-potential (SP) data inversion. The method falls within the deterministic inversion framework, and it is exclusively applicable for the interpretation of the SP anomalies measured along a profile over sheet-type structures such as conductive thin films of interconnected graphite precipitations formed on shear planes. The inverse method fits a residual SP anomaly by a single thin sheet and recovers the characteristic parameters (depth to the top h, extension in depth a, amplitude coefficient k, and amount and direction of dip θ) of the sheet. This method minimizes an objective functional in the space of the logarithmed and non-logarithmed model parameters (log(h), log(a), log(k), and θ) successively by the steepest descent (SD) and Gauss-Newton (GN) techniques in order to essentially maintain the stability and convergence of this inverse method. Prior to applying the method to real data, its accuracy, convergence, and stability are successfully verified on numerical examples with and without noise. The method is then applied to SP profiles from the German Continental Deep Drilling Program (Kontinentales Tiefbohrprogramm der Bundesrepublik Deutschla -KTB), Rittsteig, and Grossensees sites in Germany for tracing paleo-shear planes coated with graphitic deposits. The comparisons of geologic sections constructed in this paper (based on the proposed deterministic approach) against the existing published interpretations (obtained based on trial-and-error modeling) for the SP data of the KTB and Rittsteig sites have revealed that the deterministic approach suggests some new details that are of some geological significance. The findings of the proposed inverse scheme are supported by available drilling and other geophysical data. Furthermore, the real SP data of the Grossensees site have been interpreted (apparently for the first time ever) by the deterministic inverse scheme from which interpretive geologic cross sections are suggested. The computational efficiency, analysis of the numerical examples investigated, and comparisons of the real data inverted here have demonstrated that the developed deterministic approach is advantageous to the existing interpretation methods, and it is suitable for meaningful interpretation of SP data acquired elsewhere over graphitic occurrences on fault planes.

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Section: Ktb-borehole Anomaly Germanymentioning

confidence: 99%

Tracing of paleo-shear zones by self-potential data inversion: case studies from the KTB, Rittsteig, and Grossensees graphite-bearing fault planes

Mehanee

2015

Earth Planets Space

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“…The western BM is composed of various tectonometamorphic units (Franke 1989;Weber and Vollbrecht 1989, Stettner 1992. Geochronometric K-Ar data of muscovite (Wemmer 1991) indicate that the tectonometamorphic unit of the Zone of ErbendorfVohenstrauss (ZEV; Fig.…”

Section: Geological Settingmentioning

confidence: 99%

The late-and post-Variscan tectonic evolution of the Western Border fault zone of the Bohemian massif (WBZ)

Peterek¹,

Rauche

Schröder³

et al. 1997

Geologische Rundschau

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Paleostress analysis and evaluation of the stratigraphic unconformities reveal an extremely polyphase development of one of the most prominent fault zones of Central Europe, usually known as the Franconian Line (FL). Because the FL is just one fault zone, although it is the most important fault zone within a complex fault system, a more appropriate term is used herein: Western Border fault zone of the Bohemian massif (WBZ). The reconstruction of the paleostress history was carried out by analysing sequences of individual strain increments that belong to the same stratigraphic ''units'' (e.g., late-Variscan granites, Tertiary basalts). A succession of at least 15 paleostress directions and tectonic regimes have been determined since late-Variscan time.

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“…Different models of the tectonic units of the ZEV and their structural evolution have been described by many authors, e.g. Franke (1989), Vollbrecht et al (1989) and Hirschmann (1994).…”

Section: Geological Background and Previous Geochronological Datamentioning

confidence: 99%

Comparative K–Ar and Rb–Sr age determinations of retrograde processes on rocks from the KTB deep drilling project

Wemmer¹,

Ahrendt²

1997

Geol Rundsch

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Conventional K-Ar and Rb-Sr age determinations were carried out on fine mineral fractions of the KTB rocks and of rocks from the surrounding area in order to get an idea of the timing of retrograde processes which the rocks had suffered in the Late Variscan and afterwards. Coarse-grained mica minerals were used as reference minerals. It can be demonstrated that conventional K-Ar dating on fine mineral fractions is a useful tool to date retrograde processes in crystalline rocks. For methodical reasons the Rb-Sr method is less suitable. A complex age pattern was found which could be divided into different age groups representing different periods of either penetrative retrograde overprint or formation and reactivation of distinct cataclastic fault zones. Whereas the rocks of the KTB have undergone a penetrative retrograde overprint during the Permo-Triassic without any visible deformation, the Jurassic brought a first reactivation of cataclastic fault zones. In Cretaceous time an overprint led to a pronounced second reactivation of cataclastic fault zones. This latter process turned out to be the important one for the stacking and a repetition of the drilled profile in the KTB. The data and interpretations obtained on the fine mineral fractions coincide excellently with fission track data on sphene from the drill site, with sedimentological records concerning a larger regional scale and with hydrothermal alterations and ore-forming events in mid-Europe.

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The Geological Framework of the KTB Drill Site, Oberpfalz

Cited by 43 publications

References 23 publications

Tracing of paleo-shear zones by self-potential data inversion: case studies from the KTB, Rittsteig, and Grossensees graphite-bearing fault planes

Tracing of paleo-shear zones by self-potential data inversion: case studies from the KTB, Rittsteig, and Grossensees graphite-bearing fault planes

The late-and post-Variscan tectonic evolution of the Western Border fault zone of the Bohemian massif (WBZ)

Comparative K–Ar and Rb–Sr age determinations of retrograde processes on rocks from the KTB deep drilling project

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