Asdrubal Bernal1, Stuart Hardy2
(1) Manchester University, Manchester, United Kingdom
(2) University of Manchester, Manchester, United Kingdom
ABSTRACT: Coupling 3D Numerical Modelling of Compressional Structures and Sedimentation: Analysis of Structural Evolution and Syn-Tectonic Strata
Syntectonic sedimentation responds to the interplay between stratigraphic and tectonic processes in three-dimensions. Current numerical techniques generally employ two-dimensional cross-sections to investigate syntectonic sedimentation in compresional settings. In this study, the modelling of syntectonic sedimentation in three-dimensional compresional structures is achieved through use of a partial differential equation in a forward numerical approach. Structural deformation in the transport direction is described by fault-related folding and the rate of lateral growth is controlled by a scaling relationship between fault width and maximum displacement. Two geological situations are presented to simulate submarine and intermountain environments.
Modelling results highlight the differences between situations with lateral and non-lateral fold growth and suggest these can be recognised by analysis of pre- and syn-tectonic stratal geometries. Furthermore, analysis of two-dimensional cross-sections can generally lead to equivocal and often erroneous interpretation of deformation style. Syntectonic sedimentation records the distribution of accommodation along the three-dimensional structure and allows us to infer relative rates of tectonic and stratigraphic processes. Low sedimentation compared to tectonic rates and accommodation promotes offlap and onlap configurations as well as time transgressive unconformities. In high accommodation scenarios, growth triangles within syntectonic sediments do not arise. Relative rates of along strike to dip displacements can be interpreted from analysis of syntectonic strata. The numerical models compare well to outcrop and subsurface data from natural thrust systems and can be used as templates to aid interpretation of structural geometry and kinematic evolution.
AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado