| Autor: |
Shipilin, Vladimir, Colin Tanner, David, von Hartmann, Hartwig, Moeck, Inga |
| Předmět: |
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| Zdroj: |
Solid Earth Discussions; 6/15/2020, p1-42, 42p |
| Abstrakt: |
We use three-dimensional seismic reflection data from the southern German Molasse Basin to investigate the struc-tural style and evolution of a geometrically decoupled fault network in close proximity to the Alpine deformation front. We recognise two fault arrays that are vertically separated by a clay-rich detachment horizon. A large-scale thrust partially over-prints the upper fault array. Analysis of seismic stratigraphy, syn-kinematic strata, throw distribution, and spatial relationships between faults suggest a multiphase fault evolution: (1) initiation of the lower fault array in the Upper Jurassic carbonate platform during the Rupelian, (2) development of the upper fault array in the Cenozoic sediments during the Chattian, and (3) reverse reactivation of the upper faults and thrusting during the mid-Miocene. These phases document the evolution of the stress field during the migration of the forebulge (phase 1), foredeep (phase 2) and the toe of the orogenic front (phase 3) across the investigated area. We postulate that phase 2 was controlled by the vertical stress gradients, whereby a lower horizontal stress component within the Cenozoic sediments defined the independent development of the upper faults above the lower faults. Mechanical behaviour of the clay-rich horizon precluded the subsequent linkage of the fault arrays. A large-scale thrust must have been facilitated by the reverse reactivation of the upper normal faults, as its maximum displacement and extent correlate with the occurrence of these faults. We conclude that the evolving tectonic stresses were the primary mechanism of fault activation, whereas the mechanical stratigraphy and pre-existing structures locally governed the structural style. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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