Coupling of diagenetic alterations and mechanical properties of Lower Permian siliciclastic sandstones: a pilot study

Monsees, Alexander C. ORCIDiD
Biebricher, Sven F.
Busch, Benjamin ORCIDiD
Feinendegen, Martin
Ziegler, Martin ORCIDiD
Hilgers, Christoph ORCIDiD

DOI: https://doi.org/10.1007/s12665-021-09376-1
Persistent URL: http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/11298
Monsees, Alexander C.; Biebricher, Sven F.; Busch, Benjamin; Feinendegen, Martin; Ziegler, Martin; Hilgers, Christoph, 2021: Coupling of diagenetic alterations and mechanical properties of Lower Permian siliciclastic sandstones: a pilot study. In: Environmental Earth Sciences, 80, 4, DOI: https://doi.org/10.1007/s12665-021-09376-1. 
 
Monsees, Alexander C.; Structural Geology and Tectonics, Institute of Applied Geosciences, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
Biebricher, Sven F.; Chair of Geotechnical Engineering and Institute of Foundation Engineering, Soil Mechanics, Rock Mechanics and Waterways Construction, Aachen, Germany
Busch, Benjamin; Structural Geology and Tectonics, Institute of Applied Geosciences, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
Feinendegen, Martin; Chair of Geotechnical Engineering and Institute of Foundation Engineering, Soil Mechanics, Rock Mechanics and Waterways Construction, Aachen, Germany
Ziegler, Martin; Chair of Geotechnical Engineering and Institute of Foundation Engineering, Soil Mechanics, Rock Mechanics and Waterways Construction, Aachen, Germany
Hilgers, Christoph; Structural Geology and Tectonics, Institute of Applied Geosciences, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany

Abstract

Initial detrital composition and authigenic alterations during diagenesis of three sandstone types are related to their mechanical properties. Sandstones were prepared for geotechnical standard tests [density, uniaxial compressive strength (UCS), Young’s modulus (E), strain at failure (ε)] and thin sections for petrographic analyses (point counting). UCS ranges from 3 to 62 MPa and positively correlates with density (1.75–2.35 g/cm3) and E (0.3–12.7 GPa). Optical porosity is controlling these mechanical parameters and was linked to diagenetic alterations. Diagenetic alterations affecting porosity reduction are the abundance of clay minerals, and the intensity of mechanical and chemical compaction. The latter is controlled by clay mineral coatings on contacts between detrital grains, and the occurrence of authigenic quartz and dolomite. Horizontal contact lengths of grains normalized to their respective particle diameter (effective contact ratio, ECR) and porosity are identified as a control on the mechanical properties UCS and E, reflected by the rock strength index SR. The results of this pilot study suggest that SR is able to predict UCS and E based on petrographic information obtained from the studied samples. These results enhance the understanding of the coupling between mineralogy and geomechanics and highlight the impact of diagenesis on geomechanical behavior.