NUMERICAL MODELING OF THE RESPONSE TO VARIABLE STRETCHING RATE OF A DOMINO FAULT BLOCK SYSTEM

Using a numerical model of domino fault block development, the effects of a variable stretching rate during rifting were investigated. It is shown that a variable stretching rate can have an important influence on synrift sequence geometries. This can lead to complex synrift sequences composed of wedge-shaped units, formed during periods of high stretching rate, and more symmetrical units formed during periods of relative tectonic quiescence. At the fault block crest, increases in stretching rate can produce offlapping synrift sequences whereas decreases in stretching rate allow onlap onto the fault block crest. If the rifting period contains multiple pulses of stretching, complex intra-synrift unconformities can be formed. The initial bathymetry is also shown to have an important influence on the modelled synrift stratigraphy. The modelled stratigraphies are similar to those thought to result from variations in absolute sea level. Pseudo-facies markers, based on the combined initial depth and slope of deposition of the modelled sediments, are shown to be a useful tool and graphically illustrate the response of the system to pulses of tectonic activity.