Structure

Franke, Wolfgang; Rauche, H.; Stein, Eckardt

doi:10.1007/978-3-642-77518-5_24

Cited by 4 publications

(1 citation statement)

References 21 publications

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“…There must have been additional heat sources for mylonitization along the large mid‐Saxon fault because ductile conditions preceded intrusion of the Meissen pluton’s monzonite. K–Ar ages on white mica, biotite, and feldspar from the fault indicate cooling between 370 and 320 Ma from 420 °C to less than 250 °C and constrain the ductile–brittle transition between 350 and 320 Ma (Franke et al. , 1995).…”

Section: Elbe Zone and Döhlen Basinmentioning

confidence: 99%

Permo‐Silesian movements between Baltica and Western Europe: tectonics and ‘basin families’

Mattern

2001

Terra Nova

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During the late Carboniferous, NW‐trending faults of Central Europe’s Bohemian Massif acted as a dextral shear zone between Baltica and Western Europe. During the early Permian, the shear sense was reversed, and a group of strike‐slip basins formed along major NW‐trending faults. This reversal is attributed to early Permian left‐lateral motion between Baltica and Western Europe recorded by faults and basins of the Bohemian Massif. The Uralian orogeny is identified as the driving force for the sinistral motion between Baltica and Western Europe, shifting Baltica to the north‐west along the Tornquist–Teisseyre zone.

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Section: Elbe Zone and Döhlen Basinmentioning

confidence: 99%

Permo‐Silesian movements between Baltica and Western Europe: tectonics and ‘basin families’

Mattern

2001

Terra Nova

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Structure of the Saxonian Granulites: Geological and geophysical constraints on the exhumation of high‐pressure/high‐temperature rocks in the mid‐European Variscan belt

et al. 1999

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The Saxonian Granulites represent a major exposure of high‐pressure rocks within the mid‐European Variscan belt. The granulites emerge in an extensional dome structure beneath a low‐grade Paleozoic cover. The boundary between the granulites and their cover is a crustal‐scale shear zone with transport top to the SE, juxtaposing high‐pressure (HP) granulites against greenschist‐grade rocks. Seismic reflection and refraction profiling reveal that the granulite dome and its western continuation up to the SW margin of the Bohemian Massif are underlain by a reflective layer up to l s two‐way time (TWT) thickness (∼3.5 km), with P wave velocities Vp generally above 6.0 and up to 7.0 km/s (probably a sheet of metabasic rocks). This layer exhibits a NE trending antiformal structure, in line with the granulite antiform, with an apex at ∼1.2 s TWT. The outcrop of felsic granulite forms a local cap on the NE part of this high‐velocity layer. A magnetotelluric survey has revealed high resistivity in the upper crust and a zone of high conductivity under the high‐velocity layer, in the middle and lower crust, terminating ∼10 km to the south of the granulite outcrop. Similar high‐grade rocks occur in the Erzgebirge antiform SE of the Saxonian Granulites, but their exhumation was later followed by grossly westdirected stacking with medium‐pressure and low‐pressure rocks, followed by backthrusting toward the SE and late open folds. Isotopic data both from the Saxonian Granulites and the Erzgebirge indicate HP metamorphism ∼360–370 Ma, followed by a granulite stage at 350–340 Ma. This is entirely incompatible with the record of low‐grade sediments overlying the crystalline rocks, which document subsidence and marine sedimentation lasting until ∼330 Ma. This paradox is explained by tectonic underplating, differential thinning of the hanging wall lithosphere, and extensional unroofing of the high‐grade rocks derived from one of the subduction zones adjacent towards the NW and SE. Tectonic underplating and exhumation of the granulites must have occurred under the floor of a marine basin.

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Interrelated P-T-t-d Paths in the Variscan Erzgebirge Dome (Saxony, Germany): Constraints on the Rapid Exhumation of High-Pressure Rocks from the Root Zone of a Collisional Orogen

WlLLNER

Krohe

Maresch

2000

International Geology Review

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The Erzgebirge dome consists of several superimposed composite tectonometamorphic units of medium-to high-grade metamorphic rocks from different crustal depths. These exhibit high pres sure-high temperature and even ultrahigh-pressure imprints inherited from the root zone of a Variscan orogen and were exhumed almost immediately after attainment of maximum pressures at ~341 Ma. At present, the entire stack of tectonometamorphic units lies underneath an upper-crustal sequence of Paleozoic metasediments and tectonic slivers of pre-Carboniferous metamorphic rocks.Shear zones active at different times and at different depths are preserved, mainly recording two successive stages of the exhumation history between 340 and 330 Ma. Tectonic transport during exhumation was remarkably constant in an E-W direction, swinging to NW-SE in the eastern part of the Erzgebirge parallel to a ductile transtensional zone (Elbe zone) that was concomitantly active. The various tectonometamorphic units have characteristically correlated, convergent P-T-t-d paths (both "cooling during decompression" and "heating during decompression") that can be deduced from the dominant quartzofeldspathic rocks. These paths indicate successive exhumation of hotter rocks from increasingly deeper structural positions and juxtaposition against cooler rocks in higher positions, concomitant with the excision of intermediate crustal levels. We interpret this type of successive vertical telescoping of the metamorphic profile to be the result of extension of the thick ened tectonometamorphic stack.Extensional unroofing in the middle and upper crust was contemporaneous with and outlasted underthrusting and hence prograde metamorphism and deformation at deeper levels of the tectono metamorphic pile. Underthrusting is documented by a major inversion of the maximum pressure conditions in the lowermost units. However, structures related to compressional stacking now gener ally occur only as relics transposed by extensional deformation at lower pressure, or are restricted to rare small slivers with preserved prograde structures. Sedimentation of Lower Dinantian turbidites occurred along the flanks of the Erzgebirge dome during the exhumation process.The extrusion of high-pressure rocks is interpreted to have been driven mainly by a major regional buoyancy instability caused by the delamination of the lithospheric mantle underneath the neighbor ing Bohemian Massif, which represented overthickened crust at least from the Devonian to the early Visean. Major controlling factors were boundary forces exerted by the thickened crustal bulge on the neighboring thin crustal segments in the north and east, effecting lateral extension of this orogenic wedge and extrusion-i.e., convective upward flow of gravitationally unstable crustal material.

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Structure

Cited by 4 publications

References 21 publications

Permo‐Silesian movements between Baltica and Western Europe: tectonics and ‘basin families’

Permo‐Silesian movements between Baltica and Western Europe: tectonics and ‘basin families’

Structure of the Saxonian Granulites: Geological and geophysical constraints on the exhumation of high‐pressure/high‐temperature rocks in the mid‐European Variscan belt

Interrelated P-T-t-d Paths in the Variscan Erzgebirge Dome (Saxony, Germany): Constraints on the Rapid Exhumation of High-Pressure Rocks from the Root Zone of a Collisional Orogen

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