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Stress rotation – impact and interaction of rock stiffness and faults

Reiter, Karsten (2021)
Stress rotation – impact and interaction of rock stiffness and faults.
In: Solid Earth, 2021, 12 (6)
doi: 10.26083/tuprints-00019439
Article, Secondary publication, Publisher's Version

Copyright Information: CC BY 4.0 International - Creative Commons, Attribution.

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Item Type: Article
Type of entry: Secondary publication
Title: Stress rotation – impact and interaction of rock stiffness and faults
Language: English
Date: 2021
Year of primary publication: 2021
Publisher: Copernicus
Journal or Publication Title: Solid Earth
Volume of the journal: 12
Issue Number: 6
DOI: 10.26083/tuprints-00019439
Corresponding Links:
Origin: Secondary publication via sponsored Golden Open Access

It has been assumed that the orientation of the maximum horizontal compressive stress (SHmax) in the upper crust is governed on a regional scale by the same forces that drive plate motion. However, several regions are identified where stress orientation deviates from the expected orientation due to plate boundary forces (first-order stress sources), or the plate wide pattern. In some of these regions, a gradual rotation of the SHmax orientation has been observed.

Several second- and third-order stress sources have been identified in the past, which may explain stress rotation in the upper crust. For example, lateral heterogeneities in the crust, such as density and petrophysical properties, and discontinuities, such as faults, are identified as potential candidates to cause lateral stress rotations. To investigate several of these candidates, generic geomechanical numerical models are set up with up to five different units, oriented by an angle of 60° to the direction of shortening. These units have variable (elastic) material properties, such as Young's modulus, Poisson's ratio and density. In addition, the units can be separated by contact surfaces that allow them to slide along these vertical faults, depending on a chosen coefficient of friction.

The model results indicate that a density contrast or the variation of Poisson's ratio alone hardly rotates the horizontal stress (≦17°). Conversely, a contrast of Young's modulus allows significant stress rotations of up to 78°, even beyond the vicinity of the material transition (>10 km). Stress rotation clearly decreases for the same stiffness contrast, when the units are separated by low-friction discontinuities (only 19° in contrast to 78°). Low-friction discontinuities in homogeneous models do not change the stress pattern at all away from the fault (>10 km); the stress pattern is nearly identical to a model without any active faults. This indicates that material contrasts are capable of producing significant stress rotation for larger areas in the crust. Active faults that separate such material contrasts have the opposite effect – they tend to compensate for stress rotations.

Status: Publisher's Version
URN: urn:nbn:de:tuda-tuprints-194393
Classification DDC: 500 Science and mathematics > 550 Earth sciences and geology
Divisions: 11 Department of Materials and Earth Sciences > Earth Science
Date Deposited: 03 Sep 2021 12:37
Last Modified: 03 Sep 2021 12:37
URI: https://tuprints.ulb.tu-darmstadt.de/id/eprint/19439
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