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Dissolution precipitation creep as a process for the strain localisation in mafic rocks.

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Title: Dissolution precipitation creep as a process for the strain localisation in mafic rocks.
Authors: Lee, Amicia L.1 (AUTHOR) amicia.lee@uit.no, Stünitz, Holger1,2 (AUTHOR), Soret, Mathieu2 (AUTHOR), Battisti, Matheus Ariel3 (AUTHOR)
Source: Journal of Structural Geology. Feb2022, Vol. 155, pN.PAG-N.PAG. 1p.
Subjects: Strains & stresses (Mechanics), Mafic rocks, Garnet, Plagioclase, Gabbro, Low temperatures
Abstract: The lower crust is, on average, mafic in composition and composed of minerals that remain mechanically strong up to high temperatures. Here we show that dissolution-precipitation creep (as a type of diffusion creep) plays a major role in deformation of gabbro bodies at upper amphibolite facies conditions. The Kågen gabbro, N. Norway, is comprised of undeformed gabbro lenses enclosed by mylonitised margins that deformed at 690 ± 25 °C and 1.0–1.1 GPa. The evolution of the microstructures and fabric of the low strain gabbro to high strain margins were investigated. Original clinopyroxene and plagioclase dissolved during mineral reactions and precipitated as new minerals phases: new plagioclase and clinopyroxene (different compositions relative to the magmatic parents) and additional amphibole and garnet. Microstructural and crystallographic preferred orientation (CPO) data indicate that dissolution-precipitation creep is the dominant deformation mechanism. Amphibole shows a strong CPO that is primarily controlled by orientated growth in the stretching direction. The progression of mineral reactions and weakening is directly connected to a fluid-assisted transformation process that facilitates diffusion creep deformation of strong minerals at far lower stresses and temperatures than required by dislocation creep. Initially strong lithologies can become weak, provided that reactions proceed during deformation. • Deformation and coupled mineral reactions mechanically weaken strong mafic rocks. • Dissol.-precip.-creep allows viscous deformation of mafics at low temperatures. • CPO may form by growth mechanisms and shape factors instead of crystal plasticity. [ABSTRACT FROM AUTHOR]
Copyright of Journal of Structural Geology is the property of Pergamon Press - An Imprint of Elsevier Science and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
Database: Engineering Source
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DbLabel: Engineering Source
An: 155151866
AccessLevel: 6
PubType: Academic Journal
PubTypeId: academicJournal
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  Data: Dissolution precipitation creep as a process for the strain localisation in mafic rocks.
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  Data: <searchLink fieldCode="AR" term="%22Lee%2C+Amicia+L%2E%22">Lee, Amicia L.</searchLink><relatesTo>1</relatesTo> (AUTHOR)<i> amicia.lee@uit.no</i><br /><searchLink fieldCode="AR" term="%22Stünitz%2C+Holger%22">Stünitz, Holger</searchLink><relatesTo>1,2</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Soret%2C+Mathieu%22">Soret, Mathieu</searchLink><relatesTo>2</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Battisti%2C+Matheus+Ariel%22">Battisti, Matheus Ariel</searchLink><relatesTo>3</relatesTo> (AUTHOR)
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  Data: <searchLink fieldCode="DE" term="%22Strains+%26+stresses+%28Mechanics%29%22">Strains & stresses (Mechanics)</searchLink><br /><searchLink fieldCode="DE" term="%22Mafic+rocks%22">Mafic rocks</searchLink><br /><searchLink fieldCode="DE" term="%22Garnet%22">Garnet</searchLink><br /><searchLink fieldCode="DE" term="%22Plagioclase%22">Plagioclase</searchLink><br /><searchLink fieldCode="DE" term="%22Gabbro%22">Gabbro</searchLink><br /><searchLink fieldCode="DE" term="%22Low+temperatures%22">Low temperatures</searchLink>
– Name: Abstract
  Label: Abstract
  Group: Ab
  Data: The lower crust is, on average, mafic in composition and composed of minerals that remain mechanically strong up to high temperatures. Here we show that dissolution-precipitation creep (as a type of diffusion creep) plays a major role in deformation of gabbro bodies at upper amphibolite facies conditions. The Kågen gabbro, N. Norway, is comprised of undeformed gabbro lenses enclosed by mylonitised margins that deformed at 690 ± 25 °C and 1.0–1.1 GPa. The evolution of the microstructures and fabric of the low strain gabbro to high strain margins were investigated. Original clinopyroxene and plagioclase dissolved during mineral reactions and precipitated as new minerals phases: new plagioclase and clinopyroxene (different compositions relative to the magmatic parents) and additional amphibole and garnet. Microstructural and crystallographic preferred orientation (CPO) data indicate that dissolution-precipitation creep is the dominant deformation mechanism. Amphibole shows a strong CPO that is primarily controlled by orientated growth in the stretching direction. The progression of mineral reactions and weakening is directly connected to a fluid-assisted transformation process that facilitates diffusion creep deformation of strong minerals at far lower stresses and temperatures than required by dislocation creep. Initially strong lithologies can become weak, provided that reactions proceed during deformation. • Deformation and coupled mineral reactions mechanically weaken strong mafic rocks. • Dissol.-precip.-creep allows viscous deformation of mafics at low temperatures. • CPO may form by growth mechanisms and shape factors instead of crystal plasticity. [ABSTRACT FROM AUTHOR]
– Name: AbstractSuppliedCopyright
  Label:
  Group: Ab
  Data: <i>Copyright of Journal of Structural Geology is the property of Pergamon Press - An Imprint of Elsevier Science and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.)
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RecordInfo BibRecord:
  BibEntity:
    Identifiers:
      – Type: doi
        Value: 10.1016/j.jsg.2021.104505
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      – Code: eng
        Text: English
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        PageCount: 1
        StartPage: N.PAG
    Subjects:
      – SubjectFull: Strains & stresses (Mechanics)
        Type: general
      – SubjectFull: Mafic rocks
        Type: general
      – SubjectFull: Garnet
        Type: general
      – SubjectFull: Plagioclase
        Type: general
      – SubjectFull: Gabbro
        Type: general
      – SubjectFull: Low temperatures
        Type: general
    Titles:
      – TitleFull: Dissolution precipitation creep as a process for the strain localisation in mafic rocks.
        Type: main
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      – PersonEntity:
          Name:
            NameFull: Lee, Amicia L.
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            NameFull: Stünitz, Holger
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            NameFull: Soret, Mathieu
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            NameFull: Battisti, Matheus Ariel
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          Dates:
            – D: 01
              M: 02
              Text: Feb2022
              Type: published
              Y: 2022
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              Value: 155
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            – TitleFull: Journal of Structural Geology
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