CONTROL OF INTERNAL DYNAMICS OF SALT DEFORMATION DUE TO STRATIGRAPHIC ARCHITECTURE: EXPERIMENTAL MODELING

Differential loading induced deformation of a mobile substrate (e.g., salt tectonics) is an important process for the development of accommodation space and stratigraphic architectures in mini-basin settings. While previous studies of mini-basin development have explored changes to the system arising from external forces (allogeneic forces), this study focuses on the relationships between sedimentalogical patterns, stratigraphic architecture, and the internal dynamics of the system (autogenic processes). Using a silicone polymer to simulate a viscous mobile substrate, a series of simple two dimensional experiments were conducted to explore the effects of variation of sedimentation rate and style as well as changes in the thickness of the deformable layers on salt deformation. These experiments serve as an analogue model for mini-basin formation and sought to capture the internal dynamics of the system. Autogenic processes were isolated by maintaining constant sediment feed rates, as well as using a specified amount of sediment for each run regardless of the runtime. Quantification of results has allowed greater understanding of the stratigraphic and sedimentological relationships.

Experimental results show a non-linear response of created accommodation space even under constant sediment feed rates. The rate of deformation of mobile substrate is governed by the sediment feed rate, as well as substrate thickness. Observations of the experiments have shown the dependence of mini-basin geometry on sedimentological patterns. Specifically mini-basin width and depth are strongly correlative to sediment feed rate and patterns. In cases with longer substrate response time to induced load (e.g., experiments involving relatively low sediment feed rates / intermittent sedimentation) narrow and deep mini-basins developed as compared to those formed with short response time. These relationships imply that mini-basin depth and width are greatly influenced by the age of the basin, as well as the rate at which it receives sediment. Furthermore, by comparison of the changes in mini-basin architecture under different conditions a timescale for the autogenic response of deformation due to an increasing load is characterized.