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| Titel |
Analogue experiments of salt flow and pillow growth due to basement faulting and differential loading |
| VerfasserIn |
M. Warsitzka, J. Kley, N. Kukowski |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1869-9510
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| Digitales Dokument |
URL |
| Erschienen |
In: Solid Earth ; 6, no. 1 ; Nr. 6, no. 1 (2015-01-06), S.9-31 |
| Datensatznummer |
250115384
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| Publikation (Nr.) |
 copernicus.org/se-6-9-2015.pdf |
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| Zusammenfassung |
| Salt flow in sedimentary basins is mainly driven by differential loading and
can be described by the concept of hydraulic head. A hydraulic head in the
salt layer can be imposed by vertically displacing the salt layer (elevation
head) or the weight of overburden sediments (pressure head). Basement
faulting in salt-bearing extensional basins is widely acknowledged as a
potential trigger for hydraulic heads and the growth of salt structures. In
this study, scaled analogue experiments were designed to examine the
kinematics of salt flow during the early evolution of a salt structure
triggered by basement extension. In order to distinguish flow patterns
driven by elevation head or by pressure head, we applied a short pulse of
basement extension, which was followed by a long-lasting phase of
sedimentation. During the experiments viscous silicone putty simulated
ductile rock salt, and a PVC-beads/quartz-sand mixture was used to
simulate a brittle supra-salt layer. In order to derive 2-D incremental
displacement and strain patterns, the analogue experiments were monitored
using an optical image correlation system (particle imaging velocimetry). By
varying layer thicknesses and extension rates, the influence of these
parameters on the kinematics of salt flow were tested. Model results reveal
that significant flow can be triggered in the viscous layer by small-offset
basement faulting. During basement extension downward flow occurs in the
viscous layer above the basement fault tip. In contrast, upward flow takes
place during post-extensional sediment accumulation. Flow patterns in the
viscous material are characterized by channelized Poiseuille-type flow,
which is associated with subsidence in regions of "salt" expulsion and
surface uplift in regions of inflation of the viscous material. Inflation of
the viscous material eventually leads to the formation of pillow structures
adjacent to the basement faults (primary pillows). The subsidence of
peripheral sinks adjacent to the primary pillow causes the formation of
additional pillow structures at large distance from the basement fault
(secondary pillows). The experimentally obtained structures resemble those
of some natural extensional basins, e.g. the North German Basin or the
Mid-Polish Trough, and can aid understanding of the kinematics and structural
evolution of sedimentary basins characterized by the presence of salt
structures. |
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