The Mentawai forearc sliver off Sumatra: A model for a strike-slip duplex at a regional scale

2017 ◽  
Vol 710-711 ◽  
pp. 225-231 ◽  
Author(s):  
Kai Berglar ◽  
Christoph Gaedicke ◽  
Stefan Ladage ◽  
Hauke Thöle
Keyword(s):  
Regional Scale ◽  
Strike Slip ◽  
Forearc Sliver

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.

scholarly journals Deformation associated with sliver transport in Costa Rica: seismic and geodetic observations of the July 2016 Bijagua earthquake sequence

2019 ◽  
Vol 220 (1) ◽  
pp. 585-597 ◽  
Author(s):  
Maria C Araya ◽  
Juliet Biggs
Keyword(s):  
Surface Deformation ◽  
Ground Deformation ◽  
Surface Displacement ◽  
Strike Slip ◽  
Central American ◽  
Earthquake Sequence ◽  
Fault System ◽  
Aseismic Slip ◽  
Volcanic Arc ◽  
Forearc Sliver

SUMMARY Tectonic slivers form in the overriding plate in regions of oblique subduction. The inner boundaries of the sliver are often poorly defined and can consist of well-defined faults, rotating blocks or diffuse fault systems, which pass through or near the volcanic arc. The Guanacaste Volcanic Arc Sliver (GVAS) as defined by Montero et al., is a segment of the Central American Forearc Sliver, whose inner boundary is the ∼87-km-long Haciendas-Chiripa fault system (HCFS), which is located ∼10 km behind the volcanic arc and consists of strike slip faults and pull apart steps. We characterize the current ground motion on this boundary by combining earthquake locations and focal mechanisms of the 2016 Bijagua earthquake sequence, with the surface ground deformation obtained from Interferometric Synthetic Aperture Radar (InSAR) images from the ALOS-2 satellite. The coseismic stack of interferograms show ∼6 cm of displacement towards the line of sight of the satellite between the Caño Negro fault and the Upala fault, indicating uplift or SE horizontal surface displacement. The largest recorded earthquake of the sequence was Mw 5.4, and the observed deformation is one of the smallest earthquakes yet detected by InSAR in the Central American region. Forward and inverse models show the surface deformation can be partially explained by slip on a single fault, but it can be better explained by slip along two faults linked at depth. The best-fitting model consists of 0.33 m of right lateral slip on the Caño Negro fault and 0.35 m of reverse slip on the Upala fault, forming a positive flower structure. As no reverse seismicity was recorded, we infer the slip on the Upala fault occurred aseismically. Observations of the Bijagua earthquake sequence suggests the forearc sliver boundary is a complex and diffuse fault system. There are localized zones of transpression and transtension and areas where there is no surface expression suggesting the fault system is not yet mature. Although aseismic slip is common on subduction interfaces and mature strike-slip faults, this is the first study to document aseismic slip on a continental tectonic sliver boundary fault.

The Midway sequence: a Timiskaming-type, pull-apart basin deposit in the western Wawa subprovince, Minnesota

2000 ◽  
Vol 37 (1) ◽  
pp. 1-15 ◽  
Author(s):  
Mark A Jirsa
Keyword(s):  
Structural Characteristics ◽  
Regional Scale ◽  
Volcanic Rocks ◽  
Strike Slip ◽  
Alluvial Fan ◽  
Pull Apart Basin ◽  
Tectonically Active ◽  
History Of ◽  
Fluvial Sedimentation ◽  
Magmatic History

The Midway sequence is an assemblage of subaerially deposited clastic and volcanic rocks that forms a narrow wedge within Neoarchean greenstone of the western Wawa subprovince of the Superior Province. Volcanic conglomerate in the Midway sequence contains clasts of stratigraphically older greenstone, together with clasts of a distinctive hornblende-phyric trachyandesite that is not represented among the older greenstone flows. The trachyandesite forms flows and pyroclastic units that are interbedded with lenticular deposits of volcanic conglomerate in a manner interpreted to indicate approximately coeval volcanism and alluvial fan - fluvial sedimentation within a linear, restricted, and tectonically active depocentre. The Midway sequence unconformably overlies greenstone on one side and is bounded by a regional-scale, strike-slip fault on the other. Structural analyses show that the Midway sequence was deposited after an early, precleavage folding event (D1) in greenstone, but before the regional metamorphic cleavage-forming D2 deformation. Lithologic and structural attributes are consistent with deposition in a strike-slip "pull-apart" basin. The stratigraphic and structural characteristics of the Midway sequence are generally similar to those of the Timiskaming Group and Timiskaming-type rocks in Canada, and more specifically to those of the Shebandowan Group in the Thunder Bay district. This similarity implies that the latest Archean tectonic and magmatic history of the western Wawa subprovince may have been nearly synchronous over great distances.

Joint multidisciplinary study of the Saint-Sauveur–Donareo fault (lower Var valley, French Riviera): a contribution to seismic hazard assessment in the urban area of Nice

2011 ◽  
Vol 182 (4) ◽  
pp. 323-336 ◽  
Author(s):  
Christophe Larroque ◽  
Bertrand Delouis ◽  
Jean-Claude Hippolyte ◽  
Anne Deschamps ◽  
Thomas Lebourg ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Urban Areas ◽  
Regional Scale ◽  
Active Faults ◽  
Focal Depth ◽  
Strike Slip ◽  
Fault System ◽  
Geophysical Investigation ◽  
Lateral Strike Slip ◽  
North East

AbstractThe lower Var valley is the only large outcropping zone of Plio-Quaternary terrains throughout the southwestern Alps. In order to assess the seismic hazard for the Alps – Ligurian basin junction, we investigated this area to provide a record of earthquakes that have recently occurred near the city of Nice. Although no historical seismicity has been indicated for the lower Var valley, our main objective was to identify traces of recent faulting and to discuss the seismogenic potential of any active faults. We organized multidisciplinary observations as a microseismic investigation (the PASIS survey), with morphotectonic mapping and imagery, and subsurface geophysical investigations. The results of the PASIS dense recording survey were disappointing, as no present-day intense microseismic activity was recorded. From the morphotectonic investigation of the lower Var valley, we revealed several morphological anomalies, such as drainage perturbations and extended linear anomalies that are unrelated to the lithology. These anomalies strike mainly NE-SW, with the major Saint-Sauveur – Donareo lineament, clearly related to faulting of the Plio-Pleistocene sedimentary series. Sub-surface geophysical investigation (electrical resistivity tomography profiling) imaged these faults in the shallow crust, and together with the microtectonic data, allow us to propose the timing of recent faulting in this area. Normal and left-lateral strike-slip faulting occurred several times during the Pliocene. From fault-slip data, the last episode of faulting was left-lateral strike-slip and was related to a NNW-SSE direction of compression. This direction of compression is consistent with the present-day state of stress and the Saint-Sauveur–Donareo fault might have been reactivated several times as a left-lateral fault during the Quaternary. At a regional scale, in the Nice fold-and-thrust belt, these data lead to a reappraisal of the NE-SW structural trends as the major potentially active fault system. We propose that the Saint-Sauveur–Donareo fault belongs to a larger system of faults that runs from near Villeneuve-Loubet to the southwest to the Vésubie valley to the north-east. The question of a structural connection between the Vésubie – Mt Férion fault, the Saint-Sauveur–Donareo fault and its possible extension offshore through the northern Ligurian margin is discussed.The Saint-Sauveur–Donareo fault shows two en-échelon segments that extend for about 8 km. Taking into account the regional seismogenic depth (about 10 km), this fault could produce M ~6 earthquakes if activated entirely during one event. Although a moderate magnitude generally yields a moderate seismic hazard, we suggest that this contribution to the local seismic risk is high, taking into account the possible shallow focal depth and the high vulnerability of Nice and the surrounding urban areas.

scholarly journals Active Strike-Slip Faulting and Systematic Deflection of Drainage Systems along the Altyn Tagh Fault, Northern Tibetan Plateau

2021 ◽  
Vol 13 (16) ◽  
pp. 3109
Author(s):  
Peng Chen ◽  
Bing Yan ◽  
Yuan Liu
Keyword(s):  
Tibetan Plateau ◽  
Large Scale ◽  
Regional Scale ◽  
Strike Slip ◽  
The Tibetan Plateau ◽  
Stream Channels ◽  
Altyn Tagh Fault ◽  
Drainage Systems ◽  
Northern Tibetan Plateau ◽  
Altyn Tagh

Systematic deflection of drainage systems along strike-slip faults is the combination of repeated faulting slipping and continuous headward erosion accumulated on the stream channels. The measurement and analysis of systematically deflected stream channels will enhance our understanding on the deformational behaviors of strike-slip faults and the relationship between topographic response and active strike-slip faulting. In this study, detailed interpretation and analysis of remote sensing images and DEM data were carried out along the Altyn Tagh Fault, one typical large-scale strike-slip fault in the northern Tibetan Plateau, and together with the statistical results of offset amounts of 153 stream channels, revealed that (i) the drainage systems have been systematically deflected and/or offset in sinistral along the active Altyn Tagh Fault; (ii) The offset amounts recorded by stream channels vary in the range of 7 m to 72 km, and indicate a positively related linear relationship between the upstream length L and the offset amount D, the channel with bedrock upstream generally has a better correlation between L and D than that of non-bedrock upstream; (iii) River capture and abandonment are commonly developed along the Altyn Tagh Fault, which probably disturbed the continuous accumulation of offset recorded on individual stream channel, suggesting that the real maximum cumulative displacement recorded by stream channels might be larger than 72 km (lower bound) along the Altyn Tagh Fault. Along with the cumulative displacements recorded by other regional-scale strike-slip faults in the Tibetan Plateau, these results demonstrate that the magnitude of tectonic extrusion along these first-order strike-slip faults after the collision of India–Asia plates might be limited.

Complex kinematics in a major ductile shear zone, NW Shetland: Evidence of ductile extrusion during Caledonian transpression

2021 ◽  
Author(s):  
Timothy Armitage ◽  
Robert Holdsworth ◽  
Robin Strachan ◽  
Thomas Zach ◽  
Diana Alvarez-Ruiz ◽  
...  
Keyword(s):  
Shear Zone ◽  
Hanging Wall ◽  
Regional Scale ◽  
Shear Zones ◽  
White Mica ◽  
Strike Slip ◽  
Amphibolite Facies ◽  
Lateral Extrusion ◽  
Shear Sense ◽  
Ductile Shear

<p>Ductile shear zones are heterogeneous areas of strain localisation which often display variation in strain geometry and combinations of coaxial and non-coaxial deformation. One such heterogeneous shear zone is the c. 2 km thick Uyea Shear Zone (USZ) in northwest Mainland Shetland (UK), which separates variably deformed Neoarchaean orthogneisses in its footwall from Neoproterozoic metasediments in its hanging wall (Fig. a). The USZ is characterised by decimetre-scale layers of dip-slip thrusting and extension, strike-slip sinistral and dextral shear senses and interleaved ultramylonitic coaxially deformed horizons. Within the zones of transition between shear sense layers, mineral lineations swing from foliation down-dip to foliation-parallel in kinematically compatible, anticlockwise/clockwise-rotations on a local and regional scale (Fig. b). Rb-Sr dating of white mica grains via laser ablation indicates a c. 440-425 Ma Caledonian age for dip-slip and strike-slip layers and an 800 Ma Neoproterozoic age for coaxial layers. Quartz opening angles and microstructures suggest an upper-greenschist to lower-amphibolite facies temperature for deformation. We propose that a Neoproterozoic, coaxial event is overprinted by Caledonian sinistral transpression under upper greenschist/lower amphibolite facies conditions. Interleaved kinematics and mineral lineation swings are attributed to result from differential flow rates resulting in vertical and lateral extrusion and indicate regional-scale sinistral transpression during the Caledonian orogeny in NW Shetland. This study highlights the importance of linking geochronology to microstructures in a poly-deformed terrane and is a rare example of a highly heterogeneous shear zone in which both vertical and lateral extrusion occurred during transpression.</p><p><img src="https://contentmanager.copernicus.org/fileStorageProxy.php?f=gepj.0cf6ef44e5ff57820599061/sdaolpUECMynit/12UGE&app=m&a=0&c=d96bb6db75eed0739f2a6ee90c9ad8fd&ct=x&pn=gepj.elif&d=1" alt=""></p>

Tectonic evolution and related fracturing in the Causses Basin (Aveyron, France) : the Tournemire area example

2002 ◽  
Vol 173 (3) ◽  
pp. 229-243 ◽  
Author(s):  
Joël Constantin ◽  
Pierre Vergély ◽  
Justo Cabrera
Keyword(s):  
Principal Stress ◽  
Middle Eocene ◽  
Regional Scale ◽  
Strike Slip ◽  
First Episode ◽  
Experimental Site ◽  
Tectonic Event ◽  
Bedding Planes ◽  
Slip Event ◽  
History Of

Abstract The Institute for Nuclear Safety and Protection (IPSN) launched the « Tournemire » program, in 1988. One of its aims is to understand and characterize the fluid transfer processes in argillaceous rocks. They are interesting rocks for the long-term storage of nuclear waste. To this purpose, the IPSN installed an experimental site in a tunnel, which gives access to a 250 m-thick Toarcian and Domerian shale unit near Tournemire (Aveyron, France) (fig. 1). The fluids, in this type of rock with very low intrinsic permeability, 10−14 m/s [Boisson et al., 1998], used to flow (calcite crystallizations in fractures), and still flow, principally in the fractures [Barbreau et Boisson, 1993 ; Boisson, 1995] formed during the tectonic history of the formation. In order to constrain the history of fluid flow in the formation, it was necessary to characterize the tectonic fracturing and to identify the tectonic events responsible, on the one hand, for the apparition of the fractures and, on the other hand, for their eventual reactivation. The method used was a microtectonic and kinematic analysis. The studied area belongs to the western border of the Causses basin, a Permian-Mesozoic basin trending N-S. The slightly monoclinal series in this area range from the Trias, discordant westward on the Permian formations of the St-Affrique basin, to the lower Kimmerigian locally present on the Larzac plateau (fig. 1). The upper Liassic shales (Domerian, Toarcian) are between two limestone and dolomite formations. Two major (regional-scale) ESE-WNW reverse faults, the Cernon fault and the St-Jean-d’Alcapies fault, cross the area. Their offsets may reach several hundred meters. These two faults limit an ESE-WNW trending block where the experimental site is located. The tectonic fractures in the area result from two main tectonic phases. Phase 1, extensional, occurred during the Mesozoic and comprises three episodes (fig. 2). The first episode, characterised by an E-W extension (fig. 3), did not produce significant structures in the Toarcian shales. The second episode, with a NW-SE extension direction (fig. 4 and fig. 5), occurred during the diagenesis of the shales. It led to the development of calcareous nodules. These nodules are considered to be « mode I » fractures formed in association with fluid expulsion during the sediment compaction (fig. 4). The last episode has a N-S direction, (fig. 7) and is probably late Jurassic in age [Macquar, 1973 ; Blès et al., 1989 ; Martin et Bergerat, 1996]. It produced E-W conjugate normal faults (fig. 6) and two perpendicular sets of extensional joints trending E-W and N-S. The second major tectonic phase corresponds to the « pyrenean » compression. The σ1 directions vary from NE-SW to NW-SE, with two major pulses striking N020-N030 and N160-N170 (fig. 2, fig. 9 and fig. 10). The N020-N030 direction corresponds to the paroxysm of the « pyrenean » phase, dated as late Middle Eocene [Arthaud et Laurent., 1995]. It reactivated major faults and formed associated folds (fig. 8). Numerous fractures due to the N160-170 compressional event are concentrated principally in the center of the block bordered by the ESE-WNW major faults (fig. 2). Chronological criteria indicate that the direction of compression rotated counter-clockwise during the « pyrenean » compressional phase (fig. 11). A third compression direction (N130) has been evidenced, for example, by N030 trending tension gashes cross-cut by N130 trending gashes (fig. 12). The significance of this last tectonic event is unclear. It is mainly observed in the west drift of the experimental site (fig. 1C), and could result of the re-orientation of the stresses at this site close to an important shear zone. Three sets of joints, trending N020, N160 and N090 (fig. 13 and fig. 14) have been recognized. The joints are classically extensional fractures that propagate perpendicular to the minimum principal stress σ3 [Endelger, 1985 ; Pollard et Aydin, 1988 ; Rives, 1992]. In strike-slip regimes, such fractures strike parallel to the maximum principal stress σ1. The average N020, N160 and N090 joints thus very probably are created respectively during the N020 pyrenean strike-slip event, N160 strike-slip event and N-S Mesozoic extension. The established chronology between the different compressional episodes involves the reactivation of the N020 and N160 fractures may have caused only senestral strike slip. However, the presence of dextral strike slip on some vertical planes trending N-S, not associated with conjugate planes but with E-W vertical planes indicates their origin is not related to the « Pyrenean » phase. Consequently, we assumed that a set of N-S joints created during the extensive phase, in the same time as the E-W joints. An elasticity theory model gives an account of field observations on this type of fractures. The model proposed by Caputo [1995] describes the geometry of networks, of joints as a function of the tectonic regime (fig. 15). Two coeval sets of joints form under the same tectonic event. For an extensive stress state, the two sets are orthogonal to each other. Under strike slip regimes, two orthogonal sets form but one of the two sets forms horizontally (parallel to the bedding planes when the stratification is horizontal). The mechanism involves a stress permutation between σ3 and σ2 in the vicinity of the first fracture zone at the moment of failure. The network of orthogonal joints (N-S and E-W) appeared under the N-S extensive event. We show two sets of joints with the same orientation formed at two different ages (fig. 16). Their differentiation was possible with the chronology of the deformation, which was determined by the microtectonic analysis. The pre-existing fractures, originated before the « pyrenean » phase, necessarily influenced the expression and the distribution of the fractures associated with the « pyrenean » phase. These pre-existing fractures must be taken into account to understand and constrain the fluid circulations in the Toarcian shales.

scholarly journals Tectonics of the Central Part of the Adycha-Taryn Fault Zone (Verkhoyansk-Kolyma Orogenic Belt, NE Asia)

2021 ◽  
Vol 906 (1) ◽  
pp. 012109
Author(s):  
D.A. Vasiliev ◽  
A.V. Prokopiev ◽  
N.N. Ermakov
Keyword(s):  
Fault Zone ◽  
First Generation ◽  
Regional Scale ◽  
Strike Slip ◽  
Orogenic Belt ◽  
Tectonic Structures ◽  
Late Mesozoic ◽  
Deformation Stage ◽  
Fold And Thrust Belt ◽  
Dextral Strike Slip

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.

scholarly journals The role of mechanical stratigraphy on the refraction of strike-slip faults

2018 ◽  
Author(s):  
Mirko Carlini ◽  
Giulio Viola ◽  
Jussi Mattila ◽  
Luca Castellucci
Keyword(s):  
Grain Size ◽  
Failure Modes ◽  
Shear Failure ◽  
Shear Fracture ◽  
Process Zone ◽  
Regional Scale ◽  
Strike Slip ◽  
Fracture Planes ◽  
Evolutionary Scheme ◽  
Tensile Fractures

Abstract. Fault and fracture planes (FFP) that cut through multilayer sequences can be significantly refracted at layer-layer interfaces due to the different mechanical properties of the contiguous layers, such as shear strength, friction coefficient and grain size. Detailed studies of different but coexisting and broadly coeval failure modes (tensile, hybrid and shear) within multilayers deformed in extensional settings have led to infer relatively low confinement and differential stress as the boundary stress conditions at which FFP refraction occurs. Although indeed widely recognized and studied in extensional settings, the details of FFP nucleation, propagation and refraction through multilayers remain not completely understood, partly because of the common lack of geological structures documenting the incipient and intermediate stages of deformation. Here we present the results of a study on strongly refracted strike-slip FFP within the mechanically layered turbidites of the Marnoso Arenacea Formation (MAF) of the Italian Northern Apennines. The MAF is characterized by the alternation of sandstone (strong) and carbonate mudstone (weak) layers. The studied refracted FFP formed at the front of the regional-scale NE-verging Palazzuolo anticline and post-date almost any other observed structure except for a set of late extensional faults. The studied faults display coexistence of shear and hybrid (tensile-shear) failure modes and we suggest that they initially nucleated as shear fractures (mode III) within the weak layers and, only at a later stage, propagated as dilatant fractures (mode I-II) within the strong layers. The tensile fractures within the strong layers invariably contain blocky calcite infills, which are, on the other hand, almost completely absent along the shear fracture planes deforming the weak layers. Paleostress analysis was performed to constrain the NNE-SSW compressional stress field that produced the refracted FFP and to exclude the possibility that the present attitude of these structures may result from the rotation through time of faults with an initial orientation. Slip tendency analysis was also performed to infer the relative slip and dilation potentials of the observed structures. Mesoscopic analysis of preserved structures from the incipient and intermediate stages of development and evolution of the refracted FFP allowed us to build an evolutionary scheme wherein: a) Nucleation of refracted FFP occurs within weak layers; b) Refraction is primarily controlled by grain size and clay mineral content and variations thereof at layer-layer interfaces but also within individual layers; c) Propagation within strong layers occurs primarily by fluid-assisted development ahead of the FFP tip of a “process zone” defined by a network of hybrid and tensile fractures; d) The process zone causes the progressive weakening and fragmentation of the affected rock volume to eventually allow the FFP to propagate through the strong layers; e) Enhanced suitable conditions for the development of tensile and hybrid fractures can be also achieved thanks to the important role played by pressured fluids.

scholarly journals Horizontally deplacement geomasses in the continental rift geostruсtures (on the example of the Dnipro-Donets paleorift). Part 2. Structural parageneses of the reid deformation of the sedimentary cover

2019 ◽  
Keyword(s):  
Sedimentary Basin ◽  
Sedimentary Cover ◽  
Regional Scale ◽  
Strike Slip ◽  
Practical Significance ◽  
Tectonic Activity ◽  
Geodynamic Setting ◽  
Secondary Deformation ◽  
Linear Slope ◽  
Horizontal Displacements

Formulation of the problem. The inversion stages of the structural-material evolution of the continental crust are characterized by regional scale of the deformation of volume tectonic flow of platform sedimentary rocks, which caused significant horizontally-healthy movements of tectonically activated geo-mass in the intra-plate graben-rift. The dynamic deformation of geomases manifests itself at the final stages of the geological development of such structures; therefore, it determines the main features of the systemic organization of the modern architecture of the basement and sedimentary cover complexes. Review of previous publications and studies. Secondary deformation linear slope, according to Patalakha E. (1979); Alekseev V. (1990) is considered as a set of local strike-slip zones, formed on spherically-located viscous faults, forming joint tectonic flows. The structural skeleton of tectonic flows, as the basis of the tectonic dislocation process, make offsets with the horizontally and rotational component movements. Horizontal landslides are typical disjunctive elements of the continental structures formed in the geodynamic conditions of the transtension (grabens, rifts), transpression (folded mobile belts, intra-plate activation zones), as well as the basic structural elements of the strike-slip tectonics of the sedimentary basin. The purpose of the article. The second part of the trilogy continues regional geotectonic studies of post-rift complications of the sedimentary cover structure of Dnipro-Donets Paleorift (DDP), covering the three main stages of the platform tectonic activation. Late Hercynian epoch was characterized by the formation of large linear anticlinal zones and salt-shafts against the background of the general syneclizal deflection of sedimentary basin, located within the paleorift. Cimmerian epoch of tectonic activity led to significant thrust deformations of the primary structural forms of the cover in the geodynamic setting of collision compression with intensification of the horizons of the sedimentary cover. The structural manifestation of strike-slip tectonics at Alpine epoch in sedimentary complexes are mainly horizontal displacements of geomases of blocks, lineaments, local tectonic elements and structures along dynamically interconnected coulisse of strike-slip domains. Methods. Structural kinematic analysis of transformations of the fracture systems of the Upper-Visean sedimentary complex under the influence of natural mechanism of reid tectonic flow of rocks. Results. The secondary structures of strike-slip deformation, structural kinematic parageneses, dislocations zones and subregional structural waves were identified in the structure of the platform cover, which are natural geological objects formed at the inversion stages of geological development of DDP. Scientific novelty and practical significance. The result of structural manifestation of volume tectonic flow in the platform complex was horizontal displacements of the original tectonic elements, blocks, segments, structures along dynamically-linked strike-slip domains. This is caused by the formation of secondary deformation structures of various scales, morphology and genesis, which comprise longitudinal structural waves of strips of post-rift deformations in the structure of the sedimentary cover of DDP.

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