TISC: Interplay between surface and deep processes on Earth

We use computer simulation techniques to investigate the interplay between lithospheric-scale tectonics and erosion/sedimentation at the Earth's surface. TISC (formerly called tao3D) stands for Tectonics, Isostasy, Surface Transport, and Climate.

TISC is a numerical model that integrates quantitative models of lithospheric flexure, fault deformation, and surface mass transport (erosion/transport/sedimentation) along drainage networks. In other words, TISC is a computer program that simulates the evolution of 3D large-scale sediment transport together with tectonic deformation and lithospheric vertical movements on geological time scales. Particular attention is given to foreland sedimentary basin settings. Further information in this paper on the first results of this numerical model.

Take a look at some (basic) user documentation It is developed for Linux platforms only.

Example of a model run:
Click to see the 3.9 Mb animation. The panels show the evolution of the planform distribution (top view) of topography and fluvial drainage (top-left panel), lithology (top-right), and sediment thickness (bottom-left), and a cross section of the model (bottom-right). See the applicability of TISC to model foreland basins or erosional craters. . 

Document (in preparation) on the characteristics and use of the code.
 

4 main processes are implemented in the model using finite difference techniques in a planform (x,y) rectangular grid:

river drainage
The drainage river network is calculated following the maximum slope along the evolving topography. Based on the runoff distribution, the water discharge at any cell of the network is calculated as the water collected from tributary cells plus the precipitation at that cell. Lake evaporation is accounted for, enabling the model to study close endorheic basins. Both topography and the network evolves as a result of erosion, sedimentation and tectonic processes.
 
river sediment transport
Sediment carrying capacity is a function of water discharge and slope and determines whether a river is eroding or depositing. Suspended sediments resulting from erosion are transported through the fluvial network until they are deposited or they leave the model domain (explicit mass conservation).
 
lithospheric flexure
A elastic and/or viscoelastic plate approach is used to calculate the vertical movements of the lithosphere caused by the mass redistribution. In the classical lithospheric flexural model, the lithosphere is assumed to rest on a fluid asthenosphere and behave as a thin plate when submitted to external forces.
 
tectonic deformation
Tectonic modification of the relieve and the correspondent loading of the lithosphere are calculated using a cinematic vertical shear approach (preserving the vertical thickness of the moving units during displacement). 

Analogue-numerical hybrid modelling

We use a combined analogue-numerical technique to test the hypothesis that erosion/sedimentation at the Earth's surface exerts a significant effect on crustal-scale tectonics. TISC has been coupled with analogue models to simulate the potential effects that erosion may exert on the distribution of faulting and tectonic deformation of the crust. To this purpose, we have used the ISES TecLab (VU, Amsterdam), commanded by Dimitrios Sokoutis. The changes in topography in an analogue model are passed to the computer program, which calculates the spatial distribution of erosion and sedimentation. This is in turn applied back to the analogue model by manually removing/adding sand. See results and details in this paper.
Set-up of the analogue model using a sandbox to simulate the brittle deformation of the crust.

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