The terrane concept and its manifestation by deep reflection studies in the Variscides

Meißner, R.; Sadowiak, P.

doi:10.1111/j.1365-3121.1992.tb00602.x

Cited by 16 publications

(3 citation statements)

References 27 publications

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“…Surveys in the Proterozoic Baltic or North-American shields or those in the Tertiary Alpine or Himalayan belts indicate very specific reflectivity patterns (MUSACCHIO et al, 1997;GODWIN and THOMPSON, 1988;PFIFFNER et al, 1988). This has been indicated in some of our previous studies (DEKORP RESEARCH GROUP, 1990MEISSNER and SADOWIAK, 1992), concentrating on DEKORP lines, and by REY (1993) for Phanerozoic areas in general, concentrating on French and British profiles. Discussion will concern how the various reflectivity patterns might be generated, how they might survive extremely long periods, and how they might be destroyed.…”

Section: Introductionsupporting

confidence: 69%

Nature of Crustal Reflectivity along the DEKORP Profiles in Germany in Comparison with Reflection Patterns from Different Tectonic Units Worldwide: A Review

Meißner

Rabbel

1999

Pure appl. geophys.

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Reflectivity of the continental crust displays many different patterns. The DEKORP lines are used as a basis for comparing and reviewing reflectivity in different tectonic units. The (brittle) upper crust generally exhibits only two types of reflectivity. It is either rather ''transparent,'' preferably in some extensional provinces, or/and it shows traces of thrust and shear zones of former or present ruptures. As these zones have a low impedance interior (with few exceptions), their first reflection onsets have a negative polarity and evince strong, but short signals, which sometimes can be correlated over several kilometers. The (generally ductile) lower crust displays a completely different reflectivity. In warm, extensional and thin crusts the lower part is full of reflecting lamellae. It is suggested that this type of reflectivity has a thermo-rheological origin. The creation of lamellae must take place in a ductile material with contrasting impedance under extensional stresses. It can be associated with mineral alignment and corresponding seismic anisotropy. Destruction of lamellae may take place by a cooling process, transforming parts of the lower crust into a brittle regime. Small stresses might deform or break the lamellae and leave a certain dispersed reflectivity like that in some old (and cold) shields. There are no observations of reflecting lamellae in the upper crust or in the upper mantle. In all areas the Moho is the last reflecting band (reflection Moho), which most often is identical with the classical refraction Moho. There are isolated, mostly dipping, reflections in the uppermost mantle in zones where the last tectonic event, a delamination or subduction, was not succeeded by a heating process. The uppermost mantle is brittle again in most areas and may keep the memory of a (cold) collision over billions of years.

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Section: Introductionsupporting

confidence: 69%

Nature of Crustal Reflectivity along the DEKORP Profiles in Germany in Comparison with Reflection Patterns from Different Tectonic Units Worldwide: A Review

Meißner

Rabbel

1999

Pure appl. geophys.

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“…1B). While acknowledging the voluminous literature on geophysical studies of Variscan tectonics, especially in Germany and France (see Meissner and Sadowiak [1992] and Matte and Hirn [1988] for reviews), the Spanish Variscides have special relevance to the Appalachians because of the striking similarities in deep re×ection signatures. The Variscides in northwestern Spain consist of (Fig.…”

Section: Variscides Of Northwestern Spainmentioning

confidence: 99%

Review of seismic reflector signatures of crustal deformation in the Appalachian-Caledonide orogen with reference to the Spanish Variscides and the Uralides

McBride¹,

Knapp²

2002

Variscan-Appalachian Dynamics: The Building of the Late Paleozoic Basement

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After the µrst images of the crustal structure of the southern Appalachians appeared on seismic re×ection proµles in the 1970s (Cook et al., 1979), thousands of kilometers of deep seismic data were acquired over the greater Appalachian-Caledonide-Variscan orogen on both sides ABSTRACT The availability of thousands of kilometers of deep seismic re×ection proµles from the Paleozoic orogenic belts around the North Atlantic Ocean provides an unparalleled opportunity to synthesize the contrasts and similarities of crustal deformation fabrics of compressional orogens. Dominating re×ector fabrics are (1) shallow crustal sequences of subhorizontal re×ections (décollement levels) that abruptly merge with complex dipping zones (sutures or root zones), (2) broad antiformal re×ector patterns, in places underlain by a dipping planar re×ector and interpreted as asymmetric folding and shearing in the deep crust, (3) complex, subhorizontal re×ectors in the middle to lower crust that can be explained in places as intense ductile shearing related to terrane accretion and continental convergence, and (4) zones of deeply penetrating and mostly planar dipping features, interpreted as reverse-sense brittle faults or ductile shear zones. The structure of re×ectors nearer the Moho discontinuity is more complex and variable relative to planar re×ectors higher in the crust. Re×ectors that curve into the Moho seem to typify orogens where the synorogenic lowermost crust is preserved and imply that the Moho acted as a décollement. In contrast, cases where dipping planar re×ectors are abruptly cut off by a ×at Moho suggest a postorogenic process that has destroyed and reequilibrated lowermost crustal structure. Other variations between the diverse re×ector fabrics can in part be understood (and predicted) in terms of variations between thin-and thick-skinned deformation regimes, which are usually not viewed simultaneously on any one proµle or group of proµles. More recently acquired deep seismic proµles from the Spanish Variscides and the Uralides provide examples of convergent belts where most of the full crustal orogenic structure has been preserved intact. These may serve as analogs for less well preserved or evolving orogenic belts.

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“…The term 'terrane assemblage', finally, is used to indicate that a group of crustal fragments display broadly the same palaeogeographical history. Meissner & Sadowiak (1992) noted that the terrane concept is understood as an important extension of plate tectonics, based on the recognition of allochthonous, mobile geological units. Those workers furthermore indicated that the terrane concept is applied successfully to Palaeozoic Europe.…”

Section: Terrane -Terrane Assemblagementioning

confidence: 99%

Avalonia, Armorica, Perunica: terranes, microcontinents, microplates or palaeobiogeographical provinces?

Servais

Sintubin

2009

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The terrane concept and its manifestation by deep reflection studies in the Variscides

Cited by 16 publications

References 27 publications

Nature of Crustal Reflectivity along the DEKORP Profiles in Germany in Comparison with Reflection Patterns from Different Tectonic Units Worldwide: A Review

Nature of Crustal Reflectivity along the DEKORP Profiles in Germany in Comparison with Reflection Patterns from Different Tectonic Units Worldwide: A Review

Review of seismic reflector signatures of crustal deformation in the Appalachian-Caledonide orogen with reference to the Spanish Variscides and the Uralides

Avalonia, Armorica, Perunica: terranes, microcontinents, microplates or palaeobiogeographical provinces?

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