Numerical modelling of pressure solution in sandstone, rate-limiting processes and the effect of clays
E. Gundersen, D. K. Dysthe, F. Renard, K. Bjørlykke, B. Jamtveit, 2002. "Numerical modelling of pressure solution in sandstone, rate-limiting processes and the effect of clays", Deformation Mechanisms, Rheology and Tectonics: Current Status and Future Perspectives, S. de Meer, M. R. Drury, J. H. P. de Bresser, G. M. Pennock
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Pressure solution is an efficient mechanism for ductile deformation and local mass transport in the upper crust. In this paper we model pressure solution as a mechanism involving four steps: (1) dissolution at the grain contacts; (2) diffusion of solutes through fluid films at the contact between two grains; (3) transport of solutes by diffusion through the pore fluid into other adjacent open pores; and (4) precipitation on the surface of grains at their contact with the pore fluid. In this study we constrain under which conditions pressure solution is limited by one of the four processes: dissolution; contact diffusion; precipitation; and global diffusion. From our model of pressure solution, based on thermodynamic relationships we derive three dimensionless numbers which represent the competetion between the four mentioned processes. With these numbers we can define the crossover from a situation where one process acts as the limiting process to a new situation controlled by another process. We also see how the different rate-limiting processes influence the amount of mass transported during the compaction process. In addition we study the effect of clays, as it has been suggested that these minerals speed up the rate of pressure solution. We propose two models, a chemical related and a mechanical model for how the clay particles may affect the dissolution process of quartz.
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The motion and deformation of rocks are processes of fundamental importance in shaping the Earth, from outer crustal layers to the deep mantle. Reconstructions of the evolution of the Earth therefore require detailed knowledge of the geometry of deformation structures and their relative timing, of the motions leading to deformation structures and of the mechanisms governing these motions. This volume contains a collection of 22 papers on field, experimental and theoretical studies that add to our knowledge of these processes. They are a mixture of review papers oh selected topics in the field of structural geology and tectonics and papers on current issues and new techniques and are grouped into four themes:
The effect of fluids on deformation
The interpretation of microstructures and textures
Deformation mechanisms and rheology of crust and upper mantle minerals
Crust and lithosphere tectonics
The volume will appeal to researchers in the fields of structural geology and tectonophysics, both in academia and industry.