EFFECT OF PRE-EXISTING HETEROGENEITIES ON STRAIN LOCALIZATION IN A FOLIATED GRANITIC GNEISS

EFFECT OF PRE-EXISTING HETEROGENEITIES ON STRAIN LOCALIZATION IN A FOLIATED GRANITIC GNEISS

Bibliographic Details
Main Author: Kullberg, Jonathan
Language:English
Published: University of Akron / OhioLINK 2021
Subjects:
Geology
viscous
anisotropy
pre-existing heterogeneities
foliation
gneiss
Online Access:http://rave.ohiolink.edu/etdc/view?acc_num=akron1621600334762676
id ndltd-OhioLink-oai-etd.ohiolink.edu-akron1621600334762676
record_format oai_dc
spelling ndltd-OhioLink-oai-etd.ohiolink.edu-akron16216003347626762021-08-03T07:17:27Z EFFECT OF PRE-EXISTING HETEROGENEITIES ON STRAIN LOCALIZATION IN A FOLIATED GRANITIC GNEISS Kullberg, Jonathan Geology viscous anisotropy pre-existing heterogeneities foliation gneiss While Earth’s crust is often modelled as a homogenous material, heterogeneitiessuch as foliations, lattice preferred orientations (LPOs), and pre-existing brittledeformations are common and may affect the strength of the crust. To investigate theeffects of pre-existing heterogeneities on crust strength, axial compression experimentswere performed on pre-faulted samples of a fine-grained (d = 150μm) gneiss (GneissMinuti) with a granitic composition consisting of plagioclase (53%), quartz (29%),potassium feldspar (10%), biotite (7%) and accessory garnet/Fe-Ti oxides (1%). Coreswith varied orientations of foliation and lineation to the compression direction weredeformed in a Griggs-type piston rock deformation apparatus in order to determine ifthese heterogeneities would affect the strength or localization in a pre-existing fault. Aninitial brittle fault that cross-cuts the foliation was formed in all samples at low confiningpressure (Pc = 50 – 250 MPa) and temperatures (T = ~25°C). Samples were then broughtto final conditions, Pc = 1500 MPa, T = 700°C, and deformed at a constant axial strainrate of ~2 x 10-7 s-1. At final conditions, the fine-grained fault gouge of the brittle fault wasannealed and subsequently deformed by diffusion-accommodated grain boundary slidingwithin the shear zone, regardless of foliation orientation. Strain remained localized alongthe shear zone until strains of at least ~12 - 15%, and the strain rate of the low to midstrain samples within the shear zone was calculated to be ~10-5 s-1. In a sample deformedto higher strain (44%) the surrounding rock began to deform via dislocation creep. Theresults of this study suggest that strain localization will most likely be controlled by a preexistingfault, regardless of the orientation of the foliation in the surrounding host rock. 2021-06-04 English text University of Akron / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=akron1621600334762676 http://rave.ohiolink.edu/etdc/view?acc_num=akron1621600334762676 unrestricted This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.
collection NDLTD
language English
sources NDLTD
topic Geology
viscous
anisotropy
pre-existing heterogeneities
foliation
gneiss
spellingShingle Geology
viscous
anisotropy
pre-existing heterogeneities
foliation
gneiss
Kullberg, Jonathan
EFFECT OF PRE-EXISTING HETEROGENEITIES ON STRAIN LOCALIZATION IN A FOLIATED GRANITIC GNEISS
author Kullberg, Jonathan
author_facet Kullberg, Jonathan
author_sort Kullberg, Jonathan
title EFFECT OF PRE-EXISTING HETEROGENEITIES ON STRAIN LOCALIZATION IN A FOLIATED GRANITIC GNEISS
title_short EFFECT OF PRE-EXISTING HETEROGENEITIES ON STRAIN LOCALIZATION IN A FOLIATED GRANITIC GNEISS
title_full EFFECT OF PRE-EXISTING HETEROGENEITIES ON STRAIN LOCALIZATION IN A FOLIATED GRANITIC GNEISS
title_fullStr EFFECT OF PRE-EXISTING HETEROGENEITIES ON STRAIN LOCALIZATION IN A FOLIATED GRANITIC GNEISS
title_full_unstemmed EFFECT OF PRE-EXISTING HETEROGENEITIES ON STRAIN LOCALIZATION IN A FOLIATED GRANITIC GNEISS
title_sort effect of pre-existing heterogeneities on strain localization in a foliated granitic gneiss
publisher University of Akron / OhioLINK
publishDate 2021
url http://rave.ohiolink.edu/etdc/view?acc_num=akron1621600334762676
work_keys_str_mv AT kullbergjonathan effectofpreexistingheterogeneitiesonstrainlocalizationinafoliatedgraniticgneiss
_version_ 1719458430487363584

Similar Items