Structural model for the Saxothuringian-Moldanubian suture in the Variscan basement of the Oberpfalz (Northeastern Bavaria, F.R.G.) interpreted from geophysical data

Vollbrecht, Axel; Weber, Klaus; Schmoll, J.

doi:10.1016/0040-1951(89)90346-6

Cited by 56 publications

(17 citation statements)

References 13 publications

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“…Additional information on the subsurface bodies and structures was extracted from the KTB-related geophysical studies (e.g. Bu¨cker 1986;Vollbrecht et al 1989;Bosum et al 1994). The densities of the main lithostratigraphic units were adopted from published data ( Table 1).…”

Section: Granite Shapingmentioning

confidence: 99%

Subsurface distribution and tectonic setting of the late-Variscan granites in the northwestern Bohemian Massif

1997

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Integrative gravity modelling reveals the 3D shape, subsurface extent and basal morphology of the late-Variscan granites in the northwestern Bohemian Massif. The combination of the results with structural and geochronological data enables the interpretation of the morphogenesis and the tectonic setting of the granite emplacement. For the subsurface shaping two gravity methods were used: the Linsser filtering and the 2.5D density modelling. The Linsser filtering enables tomographic analyses of the gravity field in successive depth levels. The 2.5D density models were computed by the GRAVMAG program (version 1.5, British Geological Survey) which interprets gravity data vs. geological cross sections. At depth, the granites show steepand flat-sided, wedge-like plutons which are generally elongated in north-northwest-south-southeast direction. The maximum basal depths between 3 and 8 km occur along the root zones indicated by high gravity magnitudes. The western-and easternmost granites (e.g. Leuchtenberg, Bor) are deeply eroded, whereas the granites in the central part (e.g. Falkenberg, Rozvadov) are greatly buried in the metamorphic host rocks. In the northern Oberpfalz, the plutons show a west-sided basal asymmmetry, and in the western Bohemia, in contrast, the plutons have an east-sided basal asymmetry. The steep pluton flanks parallel north-northwest-south-southeast gravity gradients which result from the high density contrast of the granites and host rocks. The density contrasts are caused by steep faults which enabled the emplacement of the granites. The shape, basal morphology, depth and volume of the plutons presume a genetic link between magma intrusion and shear deformation. However, the orientation of the plutons 15-20°off the trend of the major faults and structural data suggest emplacement into opening fractures along initially transtensional faults owing to the Lower to Upper Carboniferous extension in the northwestern Bohemian Massif.

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Section: Granite Shapingmentioning

confidence: 99%

Subsurface distribution and tectonic setting of the late-Variscan granites in the northwestern Bohemian Massif

1997

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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 1I). However, they are not distinct for this reason, because the plates evidently began to collide shortly after the Pragian (Vollbrecht et al 1988). They differ because they lived in entirely different facies, and consideration of these faunas affords a fine example of how important it is to be able to recognize facies in comparing isochronous benthic faunas from restricted geographic areas.…”

Section: Use Of the Data Basementioning

confidence: 99%

Rugose coral distribution as a test of Devonian palaeogeographic models

Pedder¹,

Oliver

1990

Memoirs

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A data bank, based on stage by stage distributions of 420 rugose coral genera in 25 regions of the world is analysed, mostly by means of Otsuka coefficients, to test an Emsian reconstruction of the world proposed by Scotese. Devonian rugose corals inhabited a narrower range of facies than some other benthic groups, and even without regard to facies, provide a tool for testing geographic reconstructions. Basin dwelling coral genera typically have longer temporal and broader geographic ranges than corals living in shallower environments, and are less suitable for palaeogeographic studies. They are treated separately in this work.For the most part, conclusions drawn from the analysis are either consistent with, or positively supportive of, the Scotese reconstruction. However, large but poorly known rugose coral faunas from Mongolia and the Amur Basin are at about 60~ in the reconstruction, and other well known coral faunas, from Altai-Sayan, are at 45~176In the light of known distributions of both modern corals and Devonian southern hemisphere corals, in all recently proposed palaeogeographic reconstructions, it is questionable that the original latitude of any large northern hemisphere Devonian coral fauna would have exceeded 45 ~ .

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Structural model for the Saxothuringian-Moldanubian suture in the Variscan basement of the Oberpfalz (Northeastern Bavaria, F.R.G.) interpreted from geophysical data

Cited by 56 publications

References 13 publications

Subsurface distribution and tectonic setting of the late-Variscan granites in the northwestern Bohemian Massif

Subsurface distribution and tectonic setting of the late-Variscan granites in the northwestern Bohemian Massif

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

Rugose coral distribution as a test of Devonian palaeogeographic models

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