FINAL PROJECT: Abstract and Reader's Reponse > The Role of Fluid Chemistry, Temperature, and Pressure on Deformation Microstructures in Limestone

ABSTRACT: Interstitial pore fluids exert important control of mechanical and chemical processes taking place during rock deformation. Recent experiments show that the presence of pore fluid can significantly reduce the yield strength of Indiana limestone (Lisabeth and Zhu, 2015). I hypothesize that this reduction in yield strength results from enhanced twinning and pressure solution, owing to the relatively high solubility of calcite. Further, that twinning and pressure solution activities during deformation are sensitive to temperature and fluid chemistry. I propose to quantify the deformation microstructures of rocks deformed by Lisabeth and Zhu. Microstructures to be quantified include microcrack density, microcrack aperture, twin density, twin width, and pressure solution density of samples deformed over a range of pressures (10-50 MPa), temperatures (23-75°C), and fluid chemistry conditions. Comparison of these microstructure data will shed light on deformation mechanisms operative at different conditions. This study will provide a better understanding of chemo-thermo-mechanical coupling on deformation of carbonate rocks.
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READER’S PROFILE: I imagine my reader to be a seasoned geologist, most likely a structural geologist or one whose focus is hydrology.

READER’s RESPONSE: I am interested in reading your paper, but will I also need to read Lisabeth and Zhu (2015) to get the full story? Analyzing thin sections that have already been deformed is very practical and cuts down on time, but on the other hand you are basing your results on someone else’s work. If experiments performed in Lisabeth and Zhu were faulty or are discredited then your research is void. Also I caution you to not apply broad statements to all limestones based on the results of your experiments; limestones are very heterogeneous between units, and so the statements said about one limestone may not apply to another.
December 9, 2015 | Unregistered CommenterShayna Quidas
I spoke to Dr. C. Be sure to come to class on Friday to discuss. Will work out with two small modifications.
December 10, 2015 | Registered CommenterMarybeth Shea