Kinematic Indicators of Strike-Slip Faults in 3-D Seismic Data: Implications for Fault Propagation
A kinematic indicator is a geological structure or feature that can be used to identify both direction and magnitude of translation, in this case providing measurable piercing points for strike-slip fault offsets. We document for the first time a set of stratigraphic and structural kinematic indicators based on three-dimensional (3D) seismic reflection data. Stratigraphic types include any uniquely recognizable sedimentary feature such as meandering deepwater channels, and large intact blocks within internally disaggregated mass transport deposits. Structural indicators include the systematic offset of older intersecting faults, and thrust-propagation folds.
The examples presented here come from the deepwater Levant Basin located in the Eastern Mediterranean. This area reveals a complex network of conjugate strike-slip faults that propagated in the last two million years due to gravity driven salt tectonics. The faults are part of a contractional structural assemblage in the down-dip toe domain of the gravity linked system and detach at the Messinian evaporites. Using seismic attributes such as coherency, dip, and amplitude, the plan view geometry of these strike-slip faults is revealed across a c. 2km thick clastic overburden overlying the Messinian evaporites. This provides a unique opportunity to map kinematic indicators at points not only along strike of the faults but in depth as well, resulting in a full 3D visualisation of the fault.
The improved views of strike-slips faults in 3D enable us to analyse their evolution. Specifically, by studying the growth of precursor structures (such as R shears and en echelon normal faults) and linking them to the main through-going strike-slip fault zone, we can better understand how the ‘flower structure’ forms through time. This will not only improve our knowledge of strike-slip systems but enable further investigation into how fluid flows in these systems, thus improving success in future hydrocarbon extraction.
AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California