Superposed sedimentary and tectonic block-in-matrix fabrics in a subducted serpentinite mélange (High-pressure zermatt saas ophiolite, western alps)

Paola Tartarotti, Sara Guerini, Francesca Rotondo, Andrea Festa, Gianni Balestro, Gray Edward Bebout, Enrico Cannaò, Gabe S. Epstein, Marco Scambelluri

Research output: Contribution to journalArticle

Abstract

The primary stratigraphic fabric of a chaotic rock unit in the Zermatt Saas ophiolite of the Western Alps was reworked by a polyphase Alpine tectonic deformation. Multiscalar structural criteria demonstrate that this unit was deformed by two ductile subduction-related phases followed by brittle-ductile then brittle deformation. Deformation partitioning operated at various scales, leaving relatively unstrained rock domains preserving internal texture, organization, and composition. During subduction, ductile deformation involved stretching, boudinage, and simultaneous folding of the primary stratigraphic succession. This deformation is particularly well-documented in alternating layers showing contrasting deformation style, such as carbonate-rich rocks and turbiditic serpentinite metasandstones. During collision and exhumation, deformation enhanced the boudinaged horizons and blocks, giving rise to spherical to lozenge-shaped blocks embedded in a carbonate-rich matrix. Structural criteria allow the recognition of two main domains within the chaotic rock unit, one attributable to original broken formations reflecting turbiditic sedimentation, the other ascribable to an original sedimentary mélange. The envisaged geodynamic setting for the formation of the protoliths is the Jurassic Ligurian-Piedmont ocean basin floored by mostly serpentinized peridotites, intensely tectonized by extensional faults that triggered mass transport processes and turbiditic sedimentation.

Original languageEnglish
Article number358
JournalGeosciences (Switzerland)
Volume9
Issue number8
DOIs
Publication statusPublished - Aug 1 2019

Fingerprint

serpentinite
ophiolite
tectonics
matrix
ductile deformation
subduction
sedimentation
rock
boudinage
brittle deformation
ocean basin
mass transport
piedmont
protolith
transport process
carbonate rock
exhumation
geodynamics
folding
partitioning

Keywords

  • Broken formation
  • Ophiolite
  • Sedimentary mélange
  • Turbidite
  • Zermatt Saas

ASJC Scopus subject areas

  • Earth and Planetary Sciences(all)

Cite this

Superposed sedimentary and tectonic block-in-matrix fabrics in a subducted serpentinite mélange (High-pressure zermatt saas ophiolite, western alps). / Tartarotti, Paola; Guerini, Sara; Rotondo, Francesca; Festa, Andrea; Balestro, Gianni; Edward Bebout, Gray; Cannaò, Enrico; Epstein, Gabe S.; Scambelluri, Marco.

In: Geosciences (Switzerland), Vol. 9, No. 8, 358, 01.08.2019.

Research output: Contribution to journalArticle

Tartarotti, Paola ; Guerini, Sara ; Rotondo, Francesca ; Festa, Andrea ; Balestro, Gianni ; Edward Bebout, Gray ; Cannaò, Enrico ; Epstein, Gabe S. ; Scambelluri, Marco. / Superposed sedimentary and tectonic block-in-matrix fabrics in a subducted serpentinite mélange (High-pressure zermatt saas ophiolite, western alps). In: Geosciences (Switzerland). 2019 ; Vol. 9, No. 8.
@article{001cd31c4d1b4782bcb36989f58bd5c4,
title = "Superposed sedimentary and tectonic block-in-matrix fabrics in a subducted serpentinite m{\'e}lange (High-pressure zermatt saas ophiolite, western alps)",
abstract = "The primary stratigraphic fabric of a chaotic rock unit in the Zermatt Saas ophiolite of the Western Alps was reworked by a polyphase Alpine tectonic deformation. Multiscalar structural criteria demonstrate that this unit was deformed by two ductile subduction-related phases followed by brittle-ductile then brittle deformation. Deformation partitioning operated at various scales, leaving relatively unstrained rock domains preserving internal texture, organization, and composition. During subduction, ductile deformation involved stretching, boudinage, and simultaneous folding of the primary stratigraphic succession. This deformation is particularly well-documented in alternating layers showing contrasting deformation style, such as carbonate-rich rocks and turbiditic serpentinite metasandstones. During collision and exhumation, deformation enhanced the boudinaged horizons and blocks, giving rise to spherical to lozenge-shaped blocks embedded in a carbonate-rich matrix. Structural criteria allow the recognition of two main domains within the chaotic rock unit, one attributable to original broken formations reflecting turbiditic sedimentation, the other ascribable to an original sedimentary m{\'e}lange. The envisaged geodynamic setting for the formation of the protoliths is the Jurassic Ligurian-Piedmont ocean basin floored by mostly serpentinized peridotites, intensely tectonized by extensional faults that triggered mass transport processes and turbiditic sedimentation.",
keywords = "Broken formation, Ophiolite, Sedimentary m{\'e}lange, Turbidite, Zermatt Saas",
author = "Paola Tartarotti and Sara Guerini and Francesca Rotondo and Andrea Festa and Gianni Balestro and {Edward Bebout}, Gray and Enrico Canna{\`o} and Epstein, {Gabe S.} and Marco Scambelluri",
year = "2019",
month = "8",
day = "1",
doi = "10.3390/geosciences9080358",
language = "English",
volume = "9",
journal = "Geosciences (Switzerland)",
issn = "2076-3263",
publisher = "MDPI AG",
number = "8",

}

TY - JOUR

T1 - Superposed sedimentary and tectonic block-in-matrix fabrics in a subducted serpentinite mélange (High-pressure zermatt saas ophiolite, western alps)

AU - Tartarotti, Paola

AU - Guerini, Sara

AU - Rotondo, Francesca

AU - Festa, Andrea

AU - Balestro, Gianni

AU - Edward Bebout, Gray

AU - Cannaò, Enrico

AU - Epstein, Gabe S.

AU - Scambelluri, Marco

PY - 2019/8/1

Y1 - 2019/8/1

N2 - The primary stratigraphic fabric of a chaotic rock unit in the Zermatt Saas ophiolite of the Western Alps was reworked by a polyphase Alpine tectonic deformation. Multiscalar structural criteria demonstrate that this unit was deformed by two ductile subduction-related phases followed by brittle-ductile then brittle deformation. Deformation partitioning operated at various scales, leaving relatively unstrained rock domains preserving internal texture, organization, and composition. During subduction, ductile deformation involved stretching, boudinage, and simultaneous folding of the primary stratigraphic succession. This deformation is particularly well-documented in alternating layers showing contrasting deformation style, such as carbonate-rich rocks and turbiditic serpentinite metasandstones. During collision and exhumation, deformation enhanced the boudinaged horizons and blocks, giving rise to spherical to lozenge-shaped blocks embedded in a carbonate-rich matrix. Structural criteria allow the recognition of two main domains within the chaotic rock unit, one attributable to original broken formations reflecting turbiditic sedimentation, the other ascribable to an original sedimentary mélange. The envisaged geodynamic setting for the formation of the protoliths is the Jurassic Ligurian-Piedmont ocean basin floored by mostly serpentinized peridotites, intensely tectonized by extensional faults that triggered mass transport processes and turbiditic sedimentation.

AB - The primary stratigraphic fabric of a chaotic rock unit in the Zermatt Saas ophiolite of the Western Alps was reworked by a polyphase Alpine tectonic deformation. Multiscalar structural criteria demonstrate that this unit was deformed by two ductile subduction-related phases followed by brittle-ductile then brittle deformation. Deformation partitioning operated at various scales, leaving relatively unstrained rock domains preserving internal texture, organization, and composition. During subduction, ductile deformation involved stretching, boudinage, and simultaneous folding of the primary stratigraphic succession. This deformation is particularly well-documented in alternating layers showing contrasting deformation style, such as carbonate-rich rocks and turbiditic serpentinite metasandstones. During collision and exhumation, deformation enhanced the boudinaged horizons and blocks, giving rise to spherical to lozenge-shaped blocks embedded in a carbonate-rich matrix. Structural criteria allow the recognition of two main domains within the chaotic rock unit, one attributable to original broken formations reflecting turbiditic sedimentation, the other ascribable to an original sedimentary mélange. The envisaged geodynamic setting for the formation of the protoliths is the Jurassic Ligurian-Piedmont ocean basin floored by mostly serpentinized peridotites, intensely tectonized by extensional faults that triggered mass transport processes and turbiditic sedimentation.

KW - Broken formation

KW - Ophiolite

KW - Sedimentary mélange

KW - Turbidite

KW - Zermatt Saas

UR - http://www.scopus.com/inward/record.url?scp=85071746261&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85071746261&partnerID=8YFLogxK

U2 - 10.3390/geosciences9080358

DO - 10.3390/geosciences9080358

M3 - Article

VL - 9

JO - Geosciences (Switzerland)

JF - Geosciences (Switzerland)

SN - 2076-3263

IS - 8

M1 - 358

ER -