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|Title: ||Abutting architectures, displacement gradients, damage zone vein patterns and geochemistry of strike-slip-compartmentalized normal faults in the Jabal Qusaybah Anticline, Salakh Arc, Oman|
|Authors: ||Balsamo, Fabrizio|
|Issue Date: ||23-Jun-2014 |
|Conference: ||Geometry and growth of normal faults location:Geological Society of London date:23-25 June 2014|
|Abstract: ||In this contribution we describe normal fault zones developed in the E-W trending Jabal Qusaybah inversion anticline, at the western termination of the Salakh Arc salient, at the toe of the Oman Mountains thrust wedge. The Jabal Qusaybah anticline is characterized by a complex fault pattern developed in layered Cretaceous carbonates (Natih formation), and includes NE-SW left-lateral strike-slip and N-S extensional fault zones.
Cross-cutting relationships, geometry, petrographical features, and 13C and 18O signatures of sets of fault-related calcite veins and fault-infilling calcite crystals, indicate that strike-slip and extensional faulting occurred coevally along with the growth of the anticline.
The N-S striking normal fault zones are best developed in the central sector of the fold crest, likely due to late-stage outer-arc extension parallel to the fold axial strike. They generally abut NE-SW left-lateral strike-slip fault zones. Normal faults have displacements ranging from few dm up to ~60 m, and maximum trace length ranging from few m up to ~800 m. Fault damage zone thickness ranges from few m up to tens of meters, increasing with fault displacement. Moreover, they show widespread evidence for substantial dilation in the form of (1) dilation breccia textures, (2) multiple infilling events by large columnar calcite crystals and aggregates.
Compared with normal faults developed in other extensional settings, the fault zones exposed in Jabal Qusaybah exhibit high displacement-length ratio values, i.e. faults are one order of magnitude shorter than faults with similar displacement developed in carbonates, sandstones and volcanic tuffs. Thus, we argue that the existence of en-echelon strike-slip fault segments limits the ability of extensional fault zones to propagate horizontally. Furthermore, development of dilation breccias and fault infilling along fault zones further decrease the lateral propagation due to reseal hardening process.
These data have important implications for constraining models of hydrocarbon traps formed during non-cylindrical positive fault inversion above a basal salt layer (e.g., predicting locations of greater vertical connectivity or areas of enhanced fault connectivity). Moreover, the peculiar scaling laws characterizing these normal fault zones, combined with fracture density data, have a strong impact on fluid flow predictions in carbonate reservoirs developed in foreland thrust-fold belts.
|Publication status: ||published|
|KU Leuven publication type: ||IMa|
|Appears in Collections:||Division of Geology|
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