Effects of pre-existing faults on compaction localization in porous sandstones

Hannah Gajst*, Ram Weinberger, Wenlu Zhu, Vladimir Lyakhovsky, Shmuel Marco, Eyal Shalev

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

The formation of deformation bands can significantly modify the strength and transport properties of porous sedimentary rocks. Among the different types of deformation bands, compaction bands exhibit porosity reduction with little to no shear displacement. Natural compaction bands have previously been reported and studied in only a few areas. They often coexist with faults and other localized deformation structures. We mapped the geometrical relation between compaction bands, shear bands and faults in Lower Cretaceous porous sandstone at Makhtesh Katan, Israel. To understand the effect of pre-existing faults on the formation of compaction bands, we conducted deformation experiments on pre-faulted Bentheim sandstones. These experiments produced compaction bands consistently intersect the pre-existing fault. To gain better mechanical understanding of the observed band geometry, we also carried out three-dimensional (3D) numerical simulations with the input elastic moduli and yield strength well-constrained from the deformation experiments. We demonstrated that the formation of deformation bands is dictated by stress concentrations associated with the pre-existing fault. Frictional slip along the heterogeneous fault plane can produce a local stress concentration that would be responsible for further localized damage and the development of deformation zones. When fault slip is restricted (a possible result of high confinement), compaction bands initiate at high stress concentration sites resulting from geometrical irregularities of the fault. Finally, using a plane-strain two-dimensional (2D) linear-elastic model with the geometry of the faults mapped in the outcrop, we were able to provide a mechanical explanation of the distribution for deformation bands observed at the Makhtesh Katan study area.

Original languageEnglish
Pages (from-to)1-15
Number of pages15
JournalTectonophysics
Volume747-748
DOIs
StatePublished - 13 Nov 2018

Funding

FundersFunder number
U.S. Israel Binational Science Foundation2014036
National Science Foundation1761912
National Science Foundation
National Stroke FoundationEAR-1761912
National Stroke Foundation
United States-Israel Binational Science Foundation

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