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| Titel |
Thick- and thin-skinned tectonics of the eastern border of the Leinetal Graben, Lower Saxony, Germany, as deduced from reflection seismics |
| VerfasserIn |
David C. Tanner, Patrick Musmann, Britta Wawerzinek, Charlotte M. Krawczyk, Hermann Buness, Rüdiger Thomas |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250087366
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| Publikation (Nr.) |
 EGU/EGU2014-1401.pdf |
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| Zusammenfassung |
| The Leinetal Graben in northern Germany is a N–S striking, intra-plate tectonic graben that,
according to the youngest sediments within the graben, occurred post-Jurassic,
probably late Cretaceous. We show, by interpreting two (1.8 and 3.2 km long),
2D, P-wave, reflection-seismic profiles which cross the eastern border faults of the
Leinetal Graben, that the tectonic evolution began much earlier, probably in the Early
Triassic.
The profiles show information to a depth of approx.1 km. Using two deep boreholes
to calibrate the seismic, we interpreted the Mesozoic sedimentary layers down to
Triassic Zechstein salt and the faults that affect these strata. We recognize two sets of
faults: firstly steep, planar faults, that are closely clustered and terminate in the
Zechstein salt, and secondly shallow faults that connect between two of the first set of
faults and have very variable dip, depending on the lithology they cut at that point.
These two systems represent thick- and thin-skinned tectonics, respectively. We
envisage the late Triassic pro-Leinetal Graben structure as a salt down-building area or
as the result of rafting of sandstone units on the salt layer. The system was later
reactivated in the Late Cretaceous during intra-plate N–S compression and E–W
extension.
By restoring the deformation caused by the thin-skinned fault, we are able to determine
the amount of area change in the hanging-wall caused by the fault, due to its undulating
geometry. Area change is heterogeneous, but reaches 3–4% locally. This may well be
sufficient to allow fluids to flow in the fault damage zone in these areas. It would also account
for the different seismic appearance of the fault in the two profiles if fluids were
heterogeneously distributed along it. This method of retro-deformation is entirely
appropriate to determine the suitability of a brittle fault for, for instance, geothermal
applications. |
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