Pressure solution creep is a fundamental deformation mechanism in the upper crust. Overburden pressure that acts upon layers of sediment leaves grains densely packed. Nonhydrostatic stress distributed over the contacts between grains brings an enhancement effect on surface dissolution. As surface retreat over the contacts and hence grain repacking squeeze out pore water in the voids, the layers of sediment are deformed to become denser and denser.
This work aims to identify what process slows down pressure solution creep over time. For this purpose, a new mechanistic model of pressure solution creep is developed, derived from the reaction rate law for nonhydrostatic dissolution kinetics under the hypothesis of a closed system. The present mechanistic model shows that (1) the creep rate goes down as a combined consequence of stress transfer across expanding contacts and concentration build-up in the interlayer of absorbed water; and (2) solute migration process acts as the primary rate-limiting process of pressure solution creep in the long run.
This work then focuses on hydraulic evolution of channelling flow through a single deformable fracture which is simultaneously subjected to pressure solution creep. The developed 1-D reactive transport model is allowed to capture the strong interaction between channelling flow and pressure solution creep under crustal conditions. This numerical investigation provides a justified interpretation for the unusual experimental observation that fracture permeability reduction does not necessarily cause concentration enrichment. Temperature elevation contributes to accelerating the progression of pressure solution creep.
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa:de:qucosa:38699 |
| Date | 12 March 2020 |
| Creators | Lu, Renchao |
| Contributors | Kolditz, Olaf, Shao, Haibing, Technische Universität Dresden |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | English |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, doc-type:doctoralThesis, info:eu-repo/semantics/doctoralThesis, doc-type:Text |
| Rights | info:eu-repo/semantics/openAccess |
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