--> Strike-Slip Fault Systems and Their Kinematic Relationship to Thrust Faults in the Sinu-Offshore Thrustbelt (Colombian Caribbean Sea)

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Strike-Slip Fault Systems and Their Kinematic Relationship to Thrust Faults in the Sinu-Offshore Thrustbelt (Colombian Caribbean Sea)

Abstract

Abstract

Deformation in the Sinu-Offshore thrustbelt front in the Colombian Caribbean margin shows a related strike-slip fault system. In order to understand the deformation front it is necessary to explain the genesis of the strike-slip faults and define their temporal relationship with the thrust deformation. 3D seismic and bathymetric data were used to generate maps of the structures that define the tectonic framework of the study area. Additionally, 2D kinematic restorations were made in order to have a better understanding of deformation evolution, measure the shortening for the blocks adjacent to the strike-slip faults, and finally define whether there is compartmentalization related to the distribution of these faults or if the shortening continues. As a result of seismic mapping, it was defined that there is a strike-slip fault system oriented NW-SE cutting the structures located in the thrustbelt front subperpendicularly. These type of strike-slip faults are main features related to: (1) the presence of a detachment surface that is shared with the thrust sheets of the thrustbelt system, (2) the building of different geometric configurations of the thrust sheets on both sides of the strike-slip faults, and (3) differences in the amount of displacement between each block of the strike slip faults. All these features allow us to suggest that these strike-slip faults have a synchronism with the thrustbelt deformation front and could be considered as Tear Faults. Furthermore, the structural map analysis shows a second pattern of strike slip faults with WNW-ENE orientation; this system is also located in the same deformation front, but unlike the aforementioned system, thrust configuration on both sides of these faults allows us to observe matching between the thrust units of each block of these faults, indicating that this strike-slip fault system occurred after forming the thrustbelt and could be associated to a recent regional event.