Kinematic nature and origin of regional-scale ductile shear zones in the central Yilgarn Craton, Western Australia

2004 ◽  
Vol 394 (3-4) ◽  
pp. 139-153 ◽  
Author(s):  
She Fa Chen ◽  
John W. Libby ◽  
Stephen Wyche ◽  
Angela Riganti
Keyword(s):  
Western Australia ◽  
Regional Scale ◽  
Shear Zones ◽  
Yilgarn Craton ◽  
Ductile Shear Zones ◽  
Ductile Shear

Structure of the Lac Nominingue – Mont-Laurier region, Central Metasedimentary Belt, Quebec Grenville Province

2001 ◽  
Vol 38 (5) ◽  
pp. 787-802
Author(s):  
L B Harris ◽  
B Rivard ◽  
L Corriveau
Keyword(s):  
Regional Scale ◽  
Shear Zones ◽  
Granulite Facies ◽  
Crustal Thickening ◽  
Gneiss Dome ◽  
Grenville Province ◽  
Metasedimentary Rocks ◽  
Ductile Shear Zones ◽  
Ductile Shear ◽  
East West

The Lac Nominingue – Mont-Laurier region of the Central Metasedimentary Belt, Grenville Province of Quebec, comprises the granulite-facies Bondy gneiss complex (core of the Bondy gneiss dome) and overlying Sourd group metasedimentary rocks. A metamorphic foliation – transposed compositional layering (S1; host to peak-pressure parageneses) has been folded by isoclinal folds (F2 and F3) crosscut by leucosomes that host peak-temperature assemblages. The orthopyroxene isograd cuts obliquely across F3 folds, indicating that 1.20–1.18 Ga granulite-facies metamorphism post-dated D3. D3 structures are cut by ductile shear zones and boudinaged in D4 and are folded by regional-scale, open, upright north–south folds (F5). Folds with shallowly dipping axial surfaces (F6) are subsequently developed in the Sourd group. F5 (and probably F6) developed prior to intrusion of the ca. 1165 Ma Chevreuil suite. In the Nominingue–Chénéville deformation zone (NCDZ) east of the Bondy gneiss dome, Chevreuil intrusions contain north-striking magmatic and tectonic foliations. These, along with host gneisses and metasedimentary rocks, are displaced by conjugate ductile shear zones (northeast dextral and south-southeast sinistral) and north-northeast-striking thrusts. Late open folds (F8) with east-northeast-striking axial surfaces produce dome and basin interference patterns. F2 to F5 folds may have formed during either subhorizontal, east–west contraction or east–west extension resulting from orogenic collapse or convective lithospheric thinning following crustal thickening during terrane assembly in the Elzevirian orogeny. Structures in the NCDZ imply ESE–WNW contraction and NNE–SSW (orogen-parallel) extension in D7 syn- to post-intrusion of the Chevreuil suite. F8 folds imply a late, Grenvillian SSE–NNW contraction.

LONGEVITY OF DUCTILE SHEAR ZONES FROM DIFFUSION GEOSPEEDOMETRY OF KINEMATICALLY-SENSITIVE MINERAL INCLUSIONS

2019 ◽  
Author(s):  
William O. Nachlas ◽  
◽  
Christian Teyssier ◽  
Donna L. Whitney ◽  
Greg Hirth
Keyword(s):  
Shear Zones ◽  
Mineral Inclusions ◽  
Ductile Shear Zones ◽  
Ductile Shear

Chapter 8 Outboard-migrating accretionary orogeny at 1.9–1.8 Ga (Svecokarelian) along a margin to the continent Fennoscandia

2020 ◽  
Vol 50 (1) ◽  
pp. 237-250 ◽  
Author(s):  
Michael B. Stephens
Keyword(s):  
Base Metal ◽  
Regional Scale ◽  
Volcanic Rocks ◽  
Shear Zones ◽  
Strike Slip ◽  
Base Metal Sulphide ◽  
Metal Sulphide ◽  
Time Period ◽  
Ductile Shear Zones ◽  
Strike Slip Movement

AbstractAn intimate lithostratigraphic and lithodemic connection between syn-orogenic rock masses inside the different lithotectonic units of the 2.0–1.8 Ga (Svecokarelian) orogen, Sweden, is proposed. A repetitive cyclic tectonic evolution occurred during the time period c. 1.91–1.75 Ga, each cycle lasting about 50–55 million years. Volcanic rocks (c. 1.91–1.88 Ga) belonging to the earliest cycle are host to most of the base metal sulphide and Fe oxide deposits inside the orogen. Preservation of relict trails of continental magmatic arcs and intra-arc basins is inferred, with differences in the depth of basin deposition controlling, for example, contrasting types of base metal sulphide deposits along different trails. The segmented geometry of these continental magmatic arcs and intra-arc basins is related to strike-slip movement along ductile shear zones during transpressive events around and after 1.88 Ga; late orogenic folding also disturbed their orientation on a regional scale. A linear northwesterly orogenic trend is suggested prior to this structural overprint, the strike-slip movement being mainly parallel to the orogen. A solely accretionary orogenic model along an active margin to the continent Fennoscandia, without any trace of a terminal continent–continent collision, is preferred. Alternating retreating and advancing subduction modes that migrated progressively outboard and southwestwards in time account for the tectonic cycles.

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