A review of analogue modelling of geodynamic processes: Approaches, scaling, materials and quantification, with an application to subduction experiments

Abstract

a b s t r a c tWe present a review of the analogue modelling method, which has been used for 200 years, and continues to be used, to investigate geological phenomena and geodynamic processes. We particularly focus on the following four components: (1) the different fundamental modelling approaches that exist in analogue modelling; (2) the scaling theory and scaling of topography; (3) the different materials and rheologies that are used to simulate the complex behaviour of rocks; and (4) a range of recording techniques that are used for qualitative and quantitative analyses and interpretations of analogue models. Furthermore, we apply these four components to laboratory-based subduction models and describe some of the issues at hand with modelling such systems. Over the last 200 years, a wide variety of analogue materials have been used with different rheologies, including viscous materials (e.g. syrups, silicones, water), brittle materials (e.g. granular materials such as sand, microspheres and sugar), plastic materials (e.g. plasticine), viscoplastic materials (e.g. paraffin, waxes, petrolatum) and visco-elasto-plastic materials (e.g. hydrocarbon compounds and gelatins). These materials have been used in many different set-ups to study processes from the microscale, such as porphyroclast rotation, to the mantle scale, such as subduction and mantle convection. Despite the wide variety of modelling materials and great diversity in model set-ups and processes investigated, all laboratory experiments can be classified into one of three different categories based on three fundamental modelling approaches that have been used in analogue modelling: (1) The external approach, (2) the combined (external + internal) approach, and (3) the internal approach. In the external approach and combined approach, energy is added to the experimental system through the external application of a velocity, temperature gradient or a material influx (or a combination thereof), and so the system is open. In the external approach, all deformation in the system is driven by the externally imposed condition, while in the combined approach, part of the deformation is driven by buoyancy forces internal to the system. In the internal approach, all deformation is driven by buoyancy forces internal to the system and so the system is closed and no energy is added during an experimental run. In the combined approach, the externally imposed force or added energy is generally not quantified nor compared to the internal buoyancy force or potential energy of the system, and so it is not known if these experiments are properly scaled with respect to nature. The scaling theory requires that analogue models are geometrically, kinematically and dynamically similar to the natural prototype. Direct scaling of topography in laboratory models indicates that it is often significantly exaggerated. This can be ascribed to (1) The lack of isostatic compensation, which causes topography to be too high.(2) The lack of erosion, which causes topography to be too high....

Impact of Aseismic Ridges on Subduction Systems: Insights From Analog Modeling

“…Martinod et al () presented models with an OP and followed a combined approach (Schellart & Strak, ), combining a slab negative buoyancy force with external forces that controlled v OP by using a piston. The subduction of ARs, along with a high convergence velocity ( v C ) resulting from forced trenchward motion of the OP, resulted in an extreme decrease of the slab dip angle, achieving flat subduction, and triggered shortening in the OP.…”

Topography of the Overriding Plate During Progressive Subduction: A Dynamic Model to Explain Forearc Subsidence

“…In our experiments we scale for density contrasts in relation to the density of the sublithospheric upper mantle. For such scaling procedure, a topographic correction factor should be introduced to scale the topography developed in the models to nature (Schellart & Strak, ). Consequently, we can calculate the scaled topography in nature ( h p ) using where l p / l m is the length scale ratio, h m is the topography formed in the analogue experiments, and C Topo is the topographic correction factor where is the density of the sublithospheric upper mantle in models and is the density of the sublithospheric upper mantle in nature.…”

Central uplift collapse in acoustically fluidized granular targets: Insights from analog modeling

“…In analog experiments, granular materials such as sand or glass beads are used to mimic the discontinuous deformation of geological materials on a laboratory scale. These types of experiments are a well-established geoscientific method used to investigate the kinematics of a variety of geological deformation processes such as the formation of orogenic wedges and landslides (e.g., Davis et al 1983;Schellart and Strak 2016). Analog modeling was also applied for impact crater studies, for example, Kenkmann et al (2007), Riller et al (2010), Kenkmann and Burgert (2011), Aschauer and Kenkmann (2017).…”

“…These types of experiments are a well‐established geoscientific method used to investigate the kinematics of a variety of geological deformation processes such as the formation of orogenic wedges and landslides (e.g., Davis et al. ; Schellart and Strak ). Analog modeling was also applied for impact crater studies, for example, Kenkmann et al.…”