The use of kink bands to constrain fault displacements: an example from the Bala Lineament, Wales

1992 ◽  
Vol 129 (5) ◽  
pp. 625-632 ◽  
Author(s):  
W. T. Pratt

AbstractThe Bala Lineament is a major NE-SW-striking fault zone that crosses the Lower Palaeozoic Welsh Basin. The southwest segment of it, the Tal-y-llyn Fault, mostly lies within a tract of Ordovician mudstones with few marker bands. Consequently, post-Caledonian (early Devonian) displacements are poorly understood. However, there is a close link between the distribution of kink bands and the fault zone. The kink bands provide information about the contemporary stress conditions and, in combination with slickensided fractures, give qualitative information about the various fault displacements. Matching of major folds across the fault suggests approximately 3–4 km of dextral strike-slip, probably of Lower Carboniferous age. A younger episode of normal faulting, perhaps related to Mesozoic extension, was accompanied by kink bands with more brittle characteristics.

Author(s):  
Paul Leon Göllner ◽  
Jan Oliver Eisermann ◽  
Catalina Balbis ◽  
Ivan A. Petrinovic ◽  
Ulrich Riller

AbstractThe Southern Andes are often viewed as a classic example for kinematic partitioning of oblique plate convergence into components of continental margin-parallel strike-slip and transverse shortening. In this regard, the Liquiñe-Ofqui Fault Zone, one of Earth’s most prominent intra-arc deformation zones, is believed to be the most important crustal discontinuity in the Southern Andes taking up margin-parallel dextral strike-slip. Recent structural studies, however, are at odds with this simple concept of kinematic partitioning, due to the presence of margin-oblique and a number of other margin-parallel intra-arc deformation zones. However, knowledge on the extent of such zones in the Southern Andes is still limited. Here, we document traces of prominent structural discontinuities (lineaments) from the Southern Andes between 39° S and 46° S. In combination with compiled low-temperature thermochronology data and interpolation of respective exhumation rates, we revisit the issue of kinematic partitioning in the Southern Andes. Exhumation rates are maximal in the central parts of the orogen and discontinuity traces, trending predominantly N–S, WNW–ESE and NE–SW, are distributed across the entire width of the orogen. Notably, discontinuities coincide spatially with large gradients in Neogene exhumation rates and separate crustal domains characterized by uniform exhumation. Collectively, these relationships point to significant components of vertical displacement on these discontinuities, in addition to horizontal displacements known from published structural studies. Our results agree with previously documented Neogene shortening in the Southern Andes and indicate orogen-scale transpression with maximal vertical extrusion of rocks in the center of the transpression zone. The lineament and thermochronology data call into question the traditional view of kinematic partitioning in the Southern Andes, in which deformation is focused on the Liquiñe-Ofqui Fault Zone.


2016 ◽  
Vol 59 (5) ◽  
pp. 1025-1040 ◽  
Author(s):  
QiYun Lei ◽  
PeiZhen Zhang ◽  
WenJun Zheng ◽  
ChiZhang Chai ◽  
WeiTao Wang ◽  
...  

2021 ◽  
Vol 906 (1) ◽  
pp. 012109
Author(s):  
D.A. Vasiliev ◽  
A.V. Prokopiev ◽  
N.N. Ermakov

Abstract The study area is located in the central part of the regional-scale Adycha-Taryn fault zone separating the Adycha-El’gi and Nera anticlinoria in the hinterland of the Verkhoyansk fold-and-thrust belt (central part of the Verkhoyansk-Kolyma orogenic belt). Detailed structural studies were conducted in large quarries in the lower reaches of the El’gi River (Indigirka R. basin). In the Adycha-El’gi anticlinorium, several generations of folds, faults, and cleavage are recorded. The intensity of deformation here is found to gradually increase in NE direction. The NE wall of the Adycha-Taryn fault is thought to be more strongly deformed. The results of our investigations revealed three structural parageneses. The first paragenesis includes thrusts, reverse faults, and intense NW-striking folds of the first generation. The second paragenesis consists of less intense superposed folds of the second generation, with subvertical axes, as well as sinistral strike-slip faults. The previously made assumption is confirmed about manifestation in the study area of at least two deformation stages. We also presuppose the existence of the third deformation stage in which dextral strike-slip faults were formed. A change in the intensity of tectonic deformations both along and across the Adycha-Taryn fault zone is first established. On the southwestern side of the fault zone, the intensity of deformation structures decreases from NW to SE. On the northeastern side, the deformation intensity first increases in that same direction but then tends to diminish. An assumption is made about a growing importance of reverse faults in NW direction, along the Adycha-Taryn fault zone. Orientation of paleostress axes responsible for the formation of tectonic structures in the study area is first determined. Folds and thrusts of the first deformation stage were formed under subhorizontal compression in NE direction. Sinistral strike slips and associated folds of the second deformation stage resulted from WE-oriented subhorizontal compression. The following dextral strike-slip motions occurred in the conditions of NW-directed subhorizontal compression and NE-oriented subhorizontal extension. The studied tectonic deformations were formed in Late Mesozoic time as a result of collision-accretion events in the central part of the Verkhoyansk-Kolyma orogenic belt.


1994 ◽  
Vol 162 ◽  
pp. 113-127
Author(s):  
J.M Hull ◽  
J.A Gilotti

The Germania Land deformation zone in North-East Greenland consists of two subparallel, NW-striking strands of mylonites and cataclasites. The quasiplastic mylonites formed under low grade (biotite zone) conditions following high grade Caledonian metamorphism. Displacements on the Germania Land deformation zone and parallel zones at Danmarkshavn were predominantly dextral strike slip. Along with the similar, but sinistral, Storstrømmen shear zone, these zones record a late Caledonian phase of orogen-parallel movement. The Germania Land deformation zone is also the locus of Carboniferous normal faulting and basin development.


2021 ◽  
Vol 29 (2) ◽  
pp. 255-269
Author(s):  
Jozef Vlasáč ◽  
Martin Chovan ◽  
Rastislav Vojtko ◽  
Peter Žitňan ◽  
Tomáš Mikuš

The Finsterort and Anton vein system is located in the central zone of the Middle Miocene Štiavnica Stratovolcano between Vyhne and Hodruša-Hámre villages. The vein system contains several partial veins and veinlets and has generally NNE - SSW strike with moderate to steep eastward dip. Kinematics of the veins is characterised by older dextral strike-slip movement replaced by younger normal faulting. The mineralization is associated with the normal faults and the veins contain interesting paragenesis of Au-Ag bearing minerals. Minerals of precious metals are represented by argentotetrahedrite-(Zn) and rozhdestvenskayaite-(Zn), Au-Ag alloys, members of polybasite-pearceite and pyrargyrite-proustite solid solutions, acanthite and uytenbogaardtite. Au-Ag mineralization is accompanied by older paragenesis comprising mainly pyrite, galena, sphalerite and chalcopyrite. Besides quartz, carbonates (calcite, siderite and dolomite) are the main gangue minerals.


1988 ◽  
Vol 25 (10) ◽  
pp. 1687-1702 ◽  
Author(s):  
Michael R. McDonough ◽  
Philip S. Simony

Two gneiss bodies are contained in thrust sheets on the west edge of the Rocky Mountain Main Ranges near Valemount, British Columbia. The Bulldog Gneiss comprises Aphebian or older paragneiss and amphibolitic gneiss intruded by Aphebian orthogneiss sheets. The Yellowjacket Gneiss is granodioritic orthogneiss of unknown age. Both gneiss bodies are basement highs with thin Hadrynian metasediment cover sequences. The cover sequences are assigned to the lower Miette Group and are correlated with Horsethief Creek Group.Internal shortening of gneiss thrust sheets is expressed by recumbent folding and stacking of thin thrust sheets of gneiss and cover. The Bulldog Gneiss and its cover were carried on the postmetamorphic Purcell Thrust. The Yellowjacket Gneiss and its cover were carried on the pre- to synmetamorphic Bear Foot Thrust. Northeast and northwest displacement is documented on the moderately southwest-dipping Bear Foot Thrust, and a dextral oblique-slip – thrust model is proposed to explain the duality of thrust and dextral strike-slip kinematic indicators in mylonite from the fault. An estimate of shortening in the fore-land suggests that basement thrust sheets were translated more than 200 km to the northeast.Correlation of gneisses and cover with the westerly adjacent Malton Gneiss and its cover precludes major dextral strike-slip motion on the Southern Rocky Mountain Trench (SRMT) during and after thrusting. The SRMT was the locus of post-thrusting and postmetamorphic, Eocene(?), brittle, west-side-down, normal faulting.


2005 ◽  
Vol 42 (5) ◽  
pp. 815-832 ◽  
Author(s):  
Pierre Jutras ◽  
Gilbert Prichonnet

Viséan clastic units and structures at the northwest margin of the upper Paleozoic Maritimes Basin provide information on tectonic events that are only poorly recorded in more central parts of the basin. These continental units are time equivalent to marine sediments of the Windsor Group of Nova Scotia. They are herein assigned to the new Percé Group, which includes the La Coulée and Bonaventure formations, as well as a new unit, the Cap d'Espoir Formation. The latter unit unconformably underlies the Bonaventure Formation in a small but thick sub-basin of the Ristigouche Basin in eastern Quebec. It is characterized by a succession of sandstone and mudstone rhythmites that contrast with the coarse alluvial fan deposits of the overlying Bonaventure Formation. The Cap d'Espoir Formation was sourced from a broad area of subdued topography occupied by the Viséan La Coulée Formation and underlying units. Erosional remnants of the La Coulée Formation are unconformably overlain by the Bonaventure Formation in marginal parts of the Ristigouche Basin, whereas these units are separated by the Cap d'Espoir Formation in more central areas of the basin. The La Coulée and Cap d'Espoir formations underwent tilting and erosion during a normal faulting event that preceded deposition of the fault-controlled Bonaventure Formation. This series of events is interpreted to represent different steps in the reactivation of a pre-Carboniferous dextral strike-slip system in response to northwest–southeast compression during the Viséan in Gaspésie.


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