Across-strike geometry of the Grand Pabos fault zone: evidence for Devonian dextral transpression in the Quebec Appalachians

1993 ◽  
Vol 30 (7) ◽  
pp. 1363-1373 ◽  
Author(s):  
Donna Kirkwood ◽  
Michel Malo
Keyword(s):  
Fault Zone ◽  
High Strain ◽  
Shear Bands ◽  
Ductile Deformation ◽  
Brittle Deformation ◽  
Fault Rocks ◽  
Deformation Structures ◽  
Riedel Shear ◽  
Deformation Features ◽  
Major Fault

The principal faults of southeastern Gaspé Peninsula in Quebec consist of a central high-strain zone that is characterized by mainly ductile deformation structures and bordered by low-strain zones each dominated by brittle deformation structures. The overall geometry of shear fractures within the low-strain zones is quite similar to the expected geometry of Riedel shear fractures. The brittle structures overprint the dominant C–S-type fabric of the high-strain zone, which implies that brittle deformation outlasted ductile deformation. The asymmetry of local micro- to meso-scale deformation features along the fault zones reflects the non-coaxiality of the shear. Other features described within the fault zone (stylolitic cleavage, shear bands, and reverse faults) are evidence for a component of shortening perpendicular or oblique to the fault zone. The geometry of the Grand Pabos fault zone (GPFZ), a major fault of southern Gaspé, indicates that deeper seated fault rocks (high-strain zone) have been brought up to higher crustal levels and are presently in contact with brittlely deformed fault rocks (low-strain zone). The proposed model for the evolution of the GPFZ involves Early to Late Devonian, dextral, transcurrent movement accompanied by relatively minor amounts of vertical slip within a dextral transpressive regime. The main pulse of the Acadian orogeny in Gaspé is restricted to the Devonian and therefore occurred later than elsewhere in the Canadian Appalachians.

Jurassic and Cretaceous plutonic and structural styles of the Eagle Plutonic Complex, southwestern British Columbia, and their regional significance

1992 ◽  
Vol 29 (4) ◽  
pp. 793-811 ◽  
Author(s):  
Charles J. Greig
Keyword(s):  
Late Jurassic ◽  
High Strain ◽  
Middle Eocene ◽  
Ductile Deformation ◽  
Brittle Deformation ◽  
East Side ◽  
The West ◽  
The North ◽  
Plutonic Complex ◽  
Southwestern Margin

The Eagle Plutonic Complex is an elongate north-northwest-trending body of deformed Middle to Late Jurassic and middle Cretaceous rocks which underlies the southwestern margin of the Intermontane terrane. New mapping of the complex and its country rocks, in concert with geochronometry, has defined episodes of contractional, ductile deformation in the Middle to Late Jurassic and middle Cretaceous, as well as brittle deformation in Tertiary time. Synkinematic Middle to Late Jurassic Eagle tonalite at the eastern margin of the Eagle Complex intrudes mylonitic Nicola Group rocks and structurally overlies them along a southwest-dipping belt of high strain (Eagle shear zone) with a structural thickness of > 1 km and a strike length of > 100 km. In the central and western Eagle Complex, Eagle tonalite grades into tonalite orthogneiss (Eagle gneiss), and both are crosscut by mid-Cretaceous, muscovite-bearing plutons of the Fallslake Plutonic Suite. Fallslake Suite rocks are themselves ductilely deformed along the Pasayten fault, which bounds the Eagle Complex on the west and was active mainly in the mid-Cretaceous (ductile deformation with sinistral, east-side-up, reverse displacement). The Jurassic and Cretaceous episodes of deformation may reflect the respective initial and final stages of the accretion of the Insular terrane to the North American margin. West of the Pasayten fault, Middle to Late Jurassic and older(?) rocks of the Zoa Complex are structurally overlain, in part, by deformed Middle Eocene and middle Cretaceous sedimentary rocks. In the north, the Middle Eocene rocks are intruded on their west side by the Middle Eocene Needle Peak pluton.

scholarly journals Early gold-bearing quartz veins within the Rivière-Héva fault zone, Abitibi subprovince, Quebec, Canada

2018 ◽  
Vol 55 (10) ◽  
pp. 1139-1157 ◽  
Author(s):  
Francis Guay ◽  
Pierre Pilote ◽  
Réal Daigneault ◽  
Vicki McNicoll
Keyword(s):  
Fault Zone ◽  
Thrust Fault ◽  
Fault Zones ◽  
Ductile Deformation ◽  
Vein System ◽  
Quartz Veins ◽  
Abitibi Subprovince ◽  
Major Fault ◽  
High Degree ◽  
Gold Bearing

The Malartic Lakeshore showing is a gold-bearing quartz vein system located within the major Rivière-Héva fault zone (RHFZ) of the southern Abitibi greenstone belt. This fault separates the 2702–2700 Ma felsic Héva Formation from the 2708 Ma mafic-ultramafic Dubuisson Formation. A swarm of thin diorite dykes with lamprophyric facies and gold-bearing quartz veins are present only on the Dubuisson side of the fault. The 30–70 cm thick gold quartz veins are boudinaged and folded. Veins are banded and associated with pyrite, chalcopyrite, galena, barite, and gold. The study area is characterized by a high degree of ductile deformation associated with the RHFZ and manifested by the southeast-trending “principal schistosity” (Sp). Stretching lineations plunge moderately to shallowly toward the southeast as a result of shortening followed by late directional shearing during a transpressive deformation. A sample from the Héva Formation yielded a zircon U–Pb age of 2698.2 ± 0.8 Ma, and a diorite dyke produced an age of 2694.3 ± 2.5 Ma. Quartz veins are crosscut by dykes, and both are affected by the Sp fabric, indicating an early emplacement with respect to the deformation. This situation contrasts with the orogenic gold veins found in association with major fault zones. A near-synvolcanic magmatic hydrothermal origin is proposed for this gold vein system. Because all subvertical units in the area are south facing, the presence of the older Dubuisson Formation over the younger Héva Formation is attributed to the RHFZ acting as a significant reverse or thrust fault.

Localisation of the brittle Bathurst fault on pre-existing fabrics: a case for structural inheritance in the northeastern Slave craton, western Nunavut, Canada

2020 ◽  
Vol 57 (6) ◽  
pp. 725-746 ◽  
Author(s):  
Svieda M. Ma ◽  
Dawn A. Kellett ◽  
Laurent Godin ◽  
Michael J. Jercinovic
Keyword(s):  
Time History ◽  
Ductile Deformation ◽  
Brittle Deformation ◽  
Tectonic Zone ◽  
Fault Rocks ◽  
Rock Interaction ◽  
Slave Craton ◽  
Thelon Basin ◽  
The North ◽  
Basement Faults

The north–northwest-striking Bathurst fault in the northeastern Slave craton displaced the 1.9 Ga Kilohigok basin and the ca. 2.02–1.96 Ga Thelon tectonic zone, and projects beneath the 1.7 Ga Thelon basin where unconformity-associated uranium deposits are spatially associated with basement faults. Here we investigate the deformation–temperature–time history of the Bathurst fault rocks using structural and microstructural observations paired with U–(Th–)Pb and 40Ar/39Ar geochronology. Highly strained hornblende-bearing granitoid rocks, the predominant rock type on the northeastern side of the Bathurst fault in the study area, show ambiguous sense of shear suggesting flattening by coaxial deformation. Quartz and feldspar microstructures suggest ductile deformation occurred at ≥500 °C. Along the main fault trace, brittle features and hydrothermal alteration overprint the pervasive ductile flattening fabric. In situ U–Th–Pb dating of synkinematic monazite suggests ductile fabric formation at ca. 1933 ± 4 Ma and ca. 1895 ± 11 Ma, and zircon from a cross-cutting dyke constrains the brittle deformation to ≤1839 ± 14 Ma. 40Ar/39Ar dating of fabric-defining minerals yield cooling ages of ca. 1920–1900 Ma and ca. 1900–1850 Ma for hornblende and muscovite, respectively, and a maximum cooling age of ca. 1840 Ma for biotite. We suggest the ca. 1933–1895 Ma ductile flattening fabric developed during orthogonal collision and indentation of the Slave craton into the Thelon tectonic zone and Rae craton. Brittle deformation on the Bathurst fault was localised parallel to the ductile flattening fabric after ca. 1840 Ma and preceded Thelon basin deposition. Brittle deformation features in Bathurst fault rocks preserve evidence for fluid–rock interaction and enhanced basement permeability, suggesting the fault is a possible conduit structure for mineralising fluids.

scholarly journals Meso-scale brittle deformation structures in and around the Ikoma fault zone

2016 ◽  
Vol 122 (2) ◽  
pp. 61-74 ◽  
Author(s):  
Keisuke Mitamura ◽  
Takamoto Okudaira ◽  
Muneki Mitamura
Keyword(s):  
Fault Zone ◽  
Brittle Deformation ◽  
Deformation Structures ◽  
Meso Scale

scholarly journals Pulverized quartz clasts in gouge of the Alhama de Murcia fault (Spain): Evidence for coseismic clast pulverization in a matrix deformed by frictional sliding

Geology ◽  
2020 ◽  
Vol 48 (3) ◽  
pp. 283-287
Author(s):  
Emilio Rodríguez-Escudero ◽  
José J. Martínez-Díaz ◽  
Jorge L. Giner-Robles ◽  
Meaza Tsige ◽  
Jaime Cuevas-Rodríguez
Keyword(s):  
Structural Analysis ◽  
Shear Bands ◽  
Fracture Network ◽  
Tensile Fracture ◽  
Fault Rocks ◽  
Frictional Sliding ◽  
Riedel Shear ◽  
Seismogenic Faults ◽  
Pulverized Rocks ◽  
Southeast Spain

Abstract The fault gouge of the Alhama de Murcia fault (southeast Spain) shows a texture that resembles a mylonite, including a prominent foliation, S-C fabric, and isoclinal folds. It also embeds a large number of isolated pulverized quartz clasts (PQCs). Structural analysis indicates that the gouge fabric was mainly developed by slow frictional sliding along phyllosilicate-lined Riedel shear bands during continued shearing. In contrast, the PQCs show tensile fracture network features that are typically reported in seismically pulverized rocks found along seismogenic faults. This suggests that quartz-clast pulverization was due to a transient dilatational mechanism rather than shearing. We propose that the PQCs are the result of a rapid confined stress drop related to transient tensile stresses during coseismic ruptures that interrupt creep faulting along the gouge zone. The present study suggests that there is probably a large amount of evidence for paleoseismicity in fault rocks that is currently overlooked.

A HVEM study on the deformation microstructures of quartz in the fault rocks from a seismic fault zone in west china

1990 ◽  
Vol 48 (4) ◽  
pp. 1080-1081
Author(s):  
Lin Zhuoran ◽  
Yang Zhuen ◽  
Zhou Chunping
Keyword(s):  
Electron Microscope ◽  
Sample Preparation ◽  
Fault Zone ◽  
Dislocation Theory ◽  
Fault Rocks ◽  
West China ◽  
Deformation Structures ◽  
Voltage Electron ◽  
Seismic Fault ◽  
High Voltage Electron Microscope

Our work has been aimed at the exploratory observation and study on the intracrystalline submicron deformation structures of quartz in a series of deformed rocks occurred along the Fuyun fault zone in Xinjian, West China, which is a typical seismic one with strong activities since Cenozoic period, in connection with the corresponding works on seismology and structural petrology, using the ultra high voltage electron microscope (HVEM).With the successful method of sample preparation by select area stripping from a petrographic microscopy section and ion thinning, and with the advantages of stronger penetration power and lower radiation damage of HVEM, our observation on the intracrystalline deformation microstructure has been made more reliable and productive.In the light of dislocation theory and the experimental results of quartz deformation, up to hundred of HVEM micrographs have been analysed and summarized with reference to the current conceptual model of fault.

Cockade-bearing breccias, cataclasites and gouges in a single fault zone: Microstructures and geochemisty

2020 ◽  
Author(s):  
Alfons Berger ◽  
Marco Herwegh
Keyword(s):  
Mechanical Behavior ◽  
Fault Zone ◽  
Hydrothermal Systems ◽  
Permeability Evolution ◽  
Dynamic Changes ◽  
Fault Rocks ◽  
Local Permeability ◽  
Major Fault ◽  
Deformation Event ◽  
Fault Gouges

<p>The seismic-interseismic cycle strongly relates to the interplay between dilation owing to fracturing and frictional granular flow on one hand side and hydrothermal cementation processes on the other side. This study investigates different fault rocks of a crustal-scale fault zone in the Central Alps (Switzerland). We combine microstructural with geochemical approaches to decipher the interaction of grain size reduction via frictional processes with precipitation and resulting particle size increases. The three major fault rocks, i.e. (1) cockade-bearing breccias, (2) cataclasites, and (3) fault gouges, differ in their microstructure. The chemical data clearly demonstrate a decreasing gain of volume along this group of tectonites. Their different precipitation volumes most likely relate to dynamic changed of the local permeability of these rocks. The fluid pathways control the precipitation at different localities and times, which affect the healing of these fault rocks inducing a gain in rock strength. During the next deformation event, the extent of healing therefore directly controls the mechanical behavior of the rock. The estimated volume gain (~+110%) in cockade-bearing breccias is consistent with the seismic dilatant behavior of these frictional rocks as already proposed from other arguments (Berger and Herwegh 2019). This is in contrast to the fault-gouges with only minor gains in volume and mass resulting in a predominantly non-cohesive deformation style. This example indicates that permeability evolution (and related hydrothermal processes) strongly influences the mechanical behavior of such faults. This shows the highly dynamic behavior with time in long-lived fault systems. These dynamic changes in precipitation and resulting different strengths occur at different timescales from minutes (seismic events) to thousands of years.</p><p>Ref.: Berger, A., Herwegh, M., 2019. Cockade structures as a paleo-earthquake proxy in upper crustal hydrothermal systems. Nature Scientific Reports, 9, 9209.</p>

scholarly journals Seismic shocks, periglacial conditions and glaciotectonics as causes of the deformation of a Pleistocene meandering river succession in central Lithuania

Baltica ◽  
2019 ◽  
Vol 32 (1) ◽  
pp. 63-77
Author(s):  
Małgorzata Pisarska-Jamroży ◽  
Szymon Belzyt ◽  
Albertas Bitinas ◽  
Asta Jusienė ◽  
Barbara Woronko
Keyword(s):  
Seismic Waves ◽  
Brittle Deformation ◽  
Diverse Range ◽  
Meandering River ◽  
Deformation Structures ◽  
Deformation Features ◽  
Ice Wedge ◽  
Sediment Deformation ◽  
Sedimentary Succession ◽  
Trigger Mechanisms

An extraordinary variation of plastic and brittle deformation structures with periglacial, glaciotectonic and seismic features was observed within the unconsolidated, upper Pleistocene meandering river succession in the Slinkis outcrop in central Lithuania. Among these deformations, the following structures were described: (1) ice-wedge casts in the lower part of the sedimentary succession, linked to periglacial processes, (2) soft-sediment deformation structures, such as load structures (load casts, pseudonodules), flame structures and water/sediment-escape structures, all trapped in clearly defined layers in the upper part of the sedimentary succession, which are related to the propagation of seismic waves, and (3) faults occurring throughout the sedimentary succession, which are associated with glaciotectonic processes. To our knowledge, this is the first description and analysis of the combined presence of such a diverse range of deformation features caused by three trigger mechanisms in a meandering fluvial sedimentary succession.

scholarly journals Pressure-dependent flow behavior of Zr41.2Ti13.8Cu12.5Ni10Be22.5 bulk metallic glass

2003 ◽  
Vol 18 (9) ◽  
pp. 2039-2049 ◽  
Author(s):  
Jun Lu ◽  
Guruswami Ravichandran
Keyword(s):  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Inelastic Deformation ◽  
Shear Failure ◽  
Flow Behavior ◽  
Shear Bands ◽  
Ductile Deformation ◽  
Multiaxial Compression ◽  
Dependent Flow ◽  
Tresca Criterion

An experimental study of the inelastic deformation of bulk metallic glass Zr41.2Ti13.8Cu12.5Ni10Be22.5 under multiaxial compression using a confining sleeve technique is presented. In contrast to the catastrophic shear failure (brittle) in uniaxial compression, the metallic glass exhibited large inelastic deformation of more than 10% under confinement, demonstrating the nature of ductile deformation under constrained conditions in spite of the long-range disordered characteristic of the material. It was found that the metallic glass followed a pressure (p) dependent Tresca criterion τ = τ0 + βp, and the coefficient of the pressure dependence β was 0.17. Multiple parallel shear bands oriented at 45° to the loading direction were observed on the surfaces of the deformed specimens and were responsible for the overall inelastic deformation.

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