Quantitative
Analysis of Relay Ramp Evolution and Breaching: Implications for Structural
Interpretation of Linked Fault Arrays
Trudgill, Bruce1 (1)
The segmentation of normal fault systems
is now well established from both field and seismic interpretation analyses.
Relay ramps are ephemeral features that develop during the evolution and growth
of fault systems by linkage of overlapping segments. The controls on relay ramp
development have been discussed in a general sense, e.g., preexisting
structures, lithology, ramp width, fault overlap lengths etc., but a better
understanding of the variables that control ramp breaching is needed before any
quantitative predictions can be made as to whether or when a ramp in the subsurface
has breached. This study examines the controls on fault segmentation and growth
across a wide range of scales from small-scale field examples to large-scale
normal fault systems imaged on 3D seismic data and superbly exposed in the
field in southeast
The results of this study have important
practical implications for the structural interpretation of subsurface data
(trapping mechanisms, fault seal etc.), and understanding the growth of normal
faults through time (extensional basin evolution).
Some key questions addressed by this
study include: (1) How (and why) do controls on relay ramp breaching vary
between field, sandbox models and subsurface examples? (2) Why do sandbox model
examples show a preference for frontal breaching (55%), while field examples
show a strong preference for rearward breaching (~90%)? (3) What controls the
dip of relay ramps and how do dips vary with overlap/spacing variations? (4)
How do these variables influence trapping mechanisms for oil and gas?
AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California