Influence of fault geometry, kinematics and growth rate on syn-tectonic stratigraphic pattern: Insights from the 2D move-on-fault technique in MOVE software

Abstract

Rift-related normal faults generally have various geometries, and cause the syn-rift stratigraphy in their hanging wall to be characterized by different infilling patterns. Our understanding of the tectonic control on the syn-rift stratigraphy mainly stems from the analysis of fault kinematics, stratigraphic styles and depositional facies. However, questions remain about how fault geometry, kinematics and slip rate influence the style of a rift-related half-graben and the syn-rift stratigraphy, and what enlightenment that relationship has for the hydrocarbon exploration in rifts. Using the 2D MOVE Software, this study attempts to simulate the development of a fault-bounded half-graben, with the aim of investigating the aforementioned questions. The modeling results show that, a planar, listric and ramp-flat-ramp border fault controls a tabular, wedged-shaped, and composite wedge-shaped growth package, respectively, but exceptionally, the planar fault bounds a wedge-shaped package if the fault rotates with movement. In addition, rollover structure forms when the border fault has a listric or ramp-flat-ramp shape, indicating that the fault geometry and kinematics dominate the syn-tectonic stratigraphic pattern. Besides, fault slip rate relative to sediment supply affects the scale, dip and infilling pattern of the syn-tectonic stratigraphy. In details, reduction of fault slip rate or increment of sediment supply results in: i) the extent of the syn-tectonic stratigraphy enlarging, ii) the dip angle of the syn-tectonic stratigraphy decreasing, and iii) the water depth in the related half-graben getting shallower. This study provides insights into understanding the origin of the variable styles of rift-related half-graben and syn-rift stratigraphy. Also, our modeling results have an important implication for evaluating source rock quality in rifts. Finally, we give a preliminary example of using the MOVE Software to investigate the geometry and evolution of fault-bounded basin, which is well worth being further explored.