Salt tectonics as a self‐organizing process: A reaction, transport, and mechanics model

Abstract

Abstract. Salt tectonics is placed within the theory of nonlinear dynamical systems. Features such as waves, diapirs, and tears are viewed as natural consequences of the symmetry breaking instabilities and related self-organized dynamics of the deforming salt body coupled to the reaction, transport, and mechanics of the surrounding sediments. The fundamental nonlinearities are in the surrounding-rock and salt rheology. Our findings are based on a coupled RTM model simulated using finite element techniques. The centerpiece of the rheology of both rocks and salt is a nonlinear incremental stress formulation that integrates poroelasticity, continuous irreversible mechanical deformation (with yield behavior), pressure solution, and fracturing. In contrast to previously presented studies, in our approach the descriptive variables of all solid and fluid phases (stress, velocity, concentrations, etc.) and porous media (texture, i.e., volume fractions, composition, etc.) are solved from RTM equations accounting for interactions and interdependencies between them. The role of the coupling between the spatial distribution of sediment input rate and diapir growth and stalling is examined as is the creation of an array of salt tectonic minibasins.

Quantitative basin modeling: present state and future developments towards predictability

“…Small disturbances in the translational invariance of the system in the horizontal directions can be amplified by the RTM processes into wave, diapir, and more complex features. The controversy as to the physical laws underlying salt tectonics, and hence, in our view, the aforementioned self‐organization, still has not been completely resolved (Koen 1993; Taylor 1995; Tuncay & Ortoleva 2001). We believe that this is because, while one can rather easily conjecture a variety of mechanisms, it is likely a quantitative question as to which ones dominate in a given geologic context.…”

A possible mechanism for the spatial distribution of seismicity in northern Gulf of Mexico

“…Input parameters for the model calculations include bulk and shear moduli, and density of the blocks, and friction angle, normal and shear stiffnesses, and cohesion of the faults. In a study of salt tectonics using finite‐element simulations of a reaction, transport and mechanics model, Tuncay & Ortoleva (2001) used salt bodies with a halite composition having bulk and shear moduli of 80 and 10 GPa, respectively, and density of 2000 kg m –3 . In our models, we follow Tuncay & Ortoleva (2001) and use these representative values for the salt bodies.…”

“…In a study of salt tectonics using finite‐element simulations of a reaction, transport and mechanics model, Tuncay & Ortoleva (2001) used salt bodies with a halite composition having bulk and shear moduli of 80 and 10 GPa, respectively, and density of 2000 kg m –3 . In our models, we follow Tuncay & Ortoleva (2001) and use these representative values for the salt bodies. For the sediments surrounding the salt bodies, we compute the bulk modulus using generic formulae described in detail in Gangopadhyay et al (2004), wherein we incorporate the density, and Poisson's ratio.…”

“…The input parameters of our 3‐D model are same as those of our 2‐D models described earlier. Following Tuncay & Ortoleva (2001), we use bulk and shear moduli of 80 and 10 GPa, respectively, and density of 2000 kg m –3 for the tabular salt canopy in our model. For the surrounding sediments, we use a shear modulus of 13.23 GPa, density of 1781 kg m –3 (Huerta‐Lopez et al 2003), and along with these values use a Poisson's ratio of 0.32 (Huerta‐Lopez et al 2003) to derive the bulk modulus (33.65 GPa).…”

3D fracture network dynamics in reservoirs, faults and salt tectonic systems

“…These and other Basin RTM simulations of salt phenomena illustrate the ability of our approach to predict fractures related to salt tectonics. The details of the salt tectonics simulations are provided inTuncay & Ortoleva (2000).…”