"Multi-Scale Depositional Successions in Tectonic Settings"
Liviu C. Matenco, PhD
DeFord Distinguished Lecturer
University of Utrecht, Department of Earth Sciences
Observations in sedimentary basins affected by significant amount of deformation shows that the fault-induced depositional space, at various spatial and temporal scales, is closely linked to the basin kinematics. The tectonically-driven sediment infill reflects the history of deepening and shoaling facies controlled by the activation and changes in the fault’s offset rates. Simply stated, this translates as shifting sedimentary facies towards the basin center or towards the source area in response to increasing or decreasing depositional space. We propose a first-principle conceptual model for tectonic successions, controlled by the balance between the rates of creation of depositional space and sediment supply. These sediment bodies are bounded by succession boundaries and comprise basinward or sourceward shifting facies tracts that are separated at a point of reversal. Due to the relatively steep slopes associated with the evolution of faults, changes in sediment supply rates and mass-wasting is common phenomena in these systems and may complicate the normal rhythm of the shifting facies tracts. Once tectonic quiescence is achieved, and if the basin is connected to the open ocean, eurybatic or eustatic changes may take over and play a greater role in sediment deposition and cyclicity. The efficacy of the new concept is illustrated by examples from extensional, contractional and strike-slip basins. The basic tectonic succession model is applicable at all temporal and spatial scales and whether the tectonics cause subsidence or uplift, and in all types of tectonic settings that drive the evolution of sedimentary basins.