STRUCTURAL EVOLUTION OF THE SOUTHERN CADDO GAP QUADRANGLE, ARKANSAS: FIELD EVIDENCE FOR STRIKE-SLIP AND BACKTHRUST FAULTING IN THE OUACHITA MOUNTAINS

The Rio Preto fold belt borders the northwestern São Francisco craton and shows an exquisite kilometric doubly-vergent asymmetric fan structure, of polyphasic structural evolution attributed exclusively to the Brasiliano Orogeny (∼600-540 Ma). The fold belt can be subdivided into three structural compartments: The Northern and Southern compartments showing a general NE-SW trend, separated by the Central Compartment which shows a roughly E-W trend. The change of dip of S2, a tight crenulation foliation which is the main structure of the fold belt, between the three compartments, characterizes the fan structure. The Central Compartment is characterized by sub-vertical mylonitic quartzites, which materialize a system of low-T strike slip shear zones (Malhadinha – Rio Preto Shear Zone) crosscutting the central portion of the fold belt. In comparison to published analog models, we consider that the unique structure of the Rio Preto fold belt was generated by the oblique, dextral-sense interaction between the Cristalândia do Piauí block to the north and the São Francisco craton to the south.

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The arc of the Western Alps : understanding its kinematics and formation mechanisms based on new structural and paleomagnetic datas, and thermo-mechanical modelling.

10.5194/egusphere-egu21-16529 ◽

2021 ◽

Author(s):

Quentin Brunsmann ◽

Claudio Rosenberg ◽

Nicolas Bellahsen ◽

Laetitia Le Pourhiet

Keyword(s):

Western Alps ◽

Strike Slip ◽

Rheological Parameters ◽

The South ◽

Adriatic Plate ◽

The North ◽

Field Evidence ◽

Internal Zone ◽

The Alps ◽

East West

The Alps have an overall East-West orientation, which changes radically in their western termination, where they rotate southward into a N-S strike, and then eastward into an E-W strike, forming the arc of the Western Alps. This arc is commonly inferred to have formed during collision, due to indentation of the Adriatic plate into the European continental margin. Several models attempted to provide a kinematic explanation for the formation of this arched, lateral end of the Alps. Indeed, the radial nature of the transport directions observed along the arc of the Western Alps cannot be explained by a classic convergence model. For more than 50 years the formation of this arc was been associated to westward-directed indentation of Adria, accommodated along East-West oriented strike-slip faults, a sinistral one in the South of the arc and a dextral one in the North. The dextral one correspond to the Insubric Fault. The sinistral strike-slip zone, inferred to be localized along the &#171;Stura corridor&#187; (Piedmont, Italy) would correspond to a displacement of 100 to 150 km according to palaeogeographical, and geometric analyses. However, field evidence is scarce and barely documented in the literature. Vertical axis rotations of the Adriatic indenter also inferred to be syn-collisional could have influenced the acquisition of the morphology of the arc. Paleomagnetic analyses carried out in the Internal Zone and in the Po plain suggest a southward increading amount of counter-clockwise rotation of the Adriatic plate and the Internal Zone, varying from 20&#176;-25&#176; in the North to nearly 120&#176; in the South. Dextral shear zones possibly accommodating this rotation in some conceptual models is observed in several places below the Penninic Front and affect the Argentera massif to the south. However, the measured displacement quantities do not appear to be equivalent to those induced by such rotations. The present study aims to constrain the kinematic evolution of the arc of the Western Alps through a multidisciplinary approach. The first aspect of this project is the structural analysis of the area (Stura corridor) inferred to accommodate large sinistral displacements allowing for the westward indentation of the Adriatic indenter. We discuss the general lack of field evidence supporting sinistral strike-slip movements, in contrast to large-scale compilation of structures suggesting the possible occurrence of such displacement. The second part consists of a palaeomagnetic study, in which new data are integred with a compilation of already existing data. This compilation shows that several parts of the arc in the External Zone did not suffer any Cenozoic rotations, hence suggesting that a proto-arc already axisted at the onset collision, as suggested by independent evidence of some paleogeographic reconstruction. Finally, 2D and 3D thermo-mechanical modeling in using the pTatin3D code is used to test which structural (geometrical), and rheological parameters affected the first-order morphology of the Western Alpin arc and its kinematics. The synthesis of these different approaches allows us to propose a new model explaining the kinematics and the mechanisms of formation of the Western Alps arc.

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Proterozoic geological evolution of the northern Vestfold Hills, Antarctica

Geological Magazine ◽

10.1017/s0016756800017581 ◽

1991 ◽

Vol 128 (4) ◽

pp. 307-318 ◽

Cited By ~ 20

Author(s):

C. W. Passchier ◽

R. F. Bekendam ◽

J. D. Hoek ◽

P. G. H. M. Dirks ◽

H. de Boorder

Keyword(s):

Large Scale ◽

Structural Evolution ◽

Shear Zones ◽

Granulite Facies ◽

Strike Slip ◽

Amphibolite Facies ◽

Tectonic Event ◽

Vestfold Hills ◽

Two Phases ◽

Brittle Faulting

AbstractThe presence of polyphase shear zones transected by several suites of dolerite dykes in Archaean basement of the Vestfold Hills, East Antarctica, allows a detailed reconstruction of the local structural evolution. Archaean and early Proterozoic deformation at granulite facies conditions was followed by two phases of dolerite intrusion and mylonite generation in strike-slip zones at amphibolite facies conditions. A subsequent middle Proterozoic phase of brittle normal faulting led to the development of pseudotachylite, predating intrusion of the major swarm of dolerite dykes around 1250 Ma. During the later stages and following this event, pseudotachylite veins were reactivated as ductile, mylonitic thrusts under prograde conditions, culminating in amphibolite facies metamorphism around 1000–1100 Ma. This is possibly part of a large-scale tectonic event during which the Vestfold block was overthrust from the south. In a final phase of strike-slip deformation, several pulses of pseudotachylite-generating brittle faulting alternated with ductile reactivation of pseudotachylite.

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Structural evolution and strike-slip tectonics off north-western Sumatra

Tectonophysics ◽

10.1016/j.tecto.2009.10.003 ◽

2010 ◽

Vol 480 (1-4) ◽

pp. 119-132 ◽

Cited By ~ 27

Author(s):

Kai Berglar ◽

Christoph Gaedicke ◽

Dieter Franke ◽

Stefan Ladage ◽

Frauke Klingelhoefer ◽

...

Keyword(s):

Structural Evolution ◽

Strike Slip ◽

North Western

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Structural geology of the Lardeau Group near Trout Lake, British Columbia: implications for the structural evolution of the Kootenay Arc

Canadian Journal of Earth Sciences ◽

10.1139/e92-104 ◽

1992 ◽

Vol 29 (6) ◽

pp. 1305-1319 ◽

Cited By ~ 6

Author(s):

Moira T. Smith ◽

George E. Gehrels

Keyword(s):

British Columbia ◽

Shear Zone ◽

Structural Evolution ◽

Strike Slip ◽

Ductile Deformation ◽

Lower Paleozoic ◽

Trout Lake ◽

Facies Metamorphism ◽

Dextral Strike Slip ◽

Greenschist Facies Metamorphism

The Lardeau Group is a heterogeneous assemblage of lower Paleozoic eugeoclinal strata present in the Kootenay Arc in southeastern British Columbia. It is in fault contact with lower Paleozoic miogeoclinal strata for all or some of its length along a structure termed the Lardeau shear zone. The Lardeau Group was deformed prior to mid-Mississippian time, as manifested by layer-parallel faults, folds, and evidence for early greenschist-facies metamorphism. Regional constraints indicate probable Devono-Mississippian timing of orogeny, and possible juxtaposition of the Lardeau Group over miogeoclinal strata along the Lardeau shear zone at this time. Further ductile deformation during the Middle Jurassic Columbian orogeny produced large folds with subhorizontal axes, northwest-striking foliation and faults, and orogen-parallel stretching lineations. This deformation was apparently not everywhere synchronous, and may have continued through Late Jurassic time northeast of Trout Lake. This was followed by Cretaceous(?) dextral strike-slip and normal movement on the Lardeau shear zone and other parallel faults. While apparently the locus of several episodes of faulting, the Lardeau shear zone does not record the accretion of far-travelled tectonic fragments, as sedimentological evidence ties the Lardeau Group and other outboard units to the craton.

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Transfer Zone Characteristics in No. II Fault Zone and its Control on Petroleum, TaZhong Area

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.356-360.3009 ◽

2011 ◽

Vol 356-360 ◽

pp. 3009-3015

Author(s):

Yu Hang Zhang ◽

Xing Yan Li ◽

Zhi Feng Yan

Keyword(s):

Fault Zone ◽

Oil And Gas ◽

Structural Evolution ◽

Strike Slip ◽

Fault Analysis ◽

Seismic Profiles ◽

Oil And Gas Exploration ◽

Detachment Faults ◽

Tazhong Area ◽

Transfer Zone

According to interpreted cautiously with 2D and 3D seismic profiles, the typical transfer zone was identified in No.Ⅱ fault zone of TaZhong area, near the TaZhong 46 well of central uplift belt in Tarim basin. Discussed the transfer zone characteristic on the basis of seismic interpretation, it’s clearly triangle transfer zone and caused by strike-slip affection. Using structural analysis method, it is indicated that the transfer zone composed by thrusting-detachment faults. According to structural evolution analysis, the transfer zone had been affecting constantly by transpression during the caledonian-late hercynian, Analyzing geologic setting and regional geology characteristic, TaZhong No.Ⅱ fault zone are sinistral transpression strike-slip fault. Analysis the control action of transfer zone’s for trap, reservoir, hydrocarbon migration and sedimentary, the Transfer zone have the advantage target for oil and gas exploration.

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Structural Evolution of Ore-Controlling Trans-Crustal Faults of the Olchan-Nera Zone: Constraints from the Khangalas Ore Cluster, Yana-Kolyma Metallogenic Belt, NE Russia

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/906/1/012010 ◽

2021 ◽

Vol 906 (1) ◽

pp. 012010

Author(s):

Maxim Kudrin ◽

Valery Fridovsky

Keyword(s):

Structural Evolution ◽

Strike Slip ◽

Tectonic Structures ◽

Southeastern Part ◽

North East ◽

Metallogenic Belt ◽

Proposed Model ◽

Deformation Stages ◽

Metallogenic Zone ◽

Ne Russia

Abstract The article studies the structural evolution of ore-controlling trans-crustal faults of orogenic deposits and occurrences of the Khangalas ore cluster located in the southeastern part of the Olchan–Nera metallogenic zone, in the Upper Indigirka sector of the Yana–Kolyma metallogenic belt, North–East of Russia. Studies have shown that the formation of tectonic structures occurred during four Mesozoic deformation stages. Accretionary thrust stage D1 resulted in formation of the main pattern of the Mesozoic tectonic structures of the region. Further tectonic evolution occurred in a strike–slip setting of the accretionary D2 and post-accretionary D3–D4 stages. Post-ore strike-slip faults activate and complicate the earlier formed structures of the reverse and thrust paragenesis. Mineralization associated with the strike-slip faults has not been established, whereas formation of the gold-antimony mineralization is associated with sinistral strike–slip faults in the Adycha–Taryn metallogenic zone located to the southwest. The new data obtained are consistent with the previously proposed model of the evolution of the deformation structures of the Khangalas deposit.

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The geology and tectonic evolution of the northwest part of the Barberton Greenstone Belt, South Africa: A review

South African Journal of Geology ◽

10.25131/sajg.122.0033 ◽

2019 ◽

Vol 122 (4) ◽

pp. 421-454

Author(s):

C.R. Anhaeusser

Keyword(s):

Greenstone Belt ◽

Structural Evolution ◽

Structural Complexity ◽

Strike Slip ◽

Schist Belt ◽

Progressive Deformation ◽

Barberton Greenstone Belt ◽

Wide Range ◽

Area North ◽

Granitoid Intrusions

AbstractFormations on the northwestern flank of the Barberton Greenstone Belt have hosted over 85% of all the gold recovered from the ca. 3550 to 3000 Ma Barberton Supergroup since early discoveries in 1872. This sector of the greenstone belt also happens to coincide with a complex tectonic architecture resulting from successive stages of folding and faulting superimposed onto a complex lithostratigraphy. Of particular importance has been the influence of two diapiric granitoid intrusions that caused added structural complexity following their emplacement ca. 3227 to 3250 Ma. Of these the larger Kaap Valley Pluton invaded the area north of present day Barberton town causing the separation of the greenstones into a northern arm (Jamestown Schist Belt) and a southern sector which remained attached to the main greenstone belt (Moodies Hills). The ballooning pluton produced vertical as well as horizontal flattening stresses, the latter reactivating earlier high-angle faults and resulting in subhorizontal strike-slip movements, particularly along the Barbrook Fault Zone, which acted as a right-lateral strike-slip fault. Formations north of this fault were buckled, following progressive deformation in the region known as the Sheba Hills, into major synclinal folds (Eureka and Ulundi Synclines) with folded axial planes that dip steeply to the south, southeast or east. The second granitoid intrusion (Stentor Pluton), which has been extensively modified by subsequent magmatic events, caused significant flattening of greenstone belt rocks in the northeastern part of the Barberton Greenstone Belt (Three Sisters region) as well as in other areas rimming the granitic body. Combined, the two plutons produced a wide range of interference and reactivated structures particularly affecting a triangular region extending from the Jamestown Schist Belt into the area occupied by the New Consort Gold Mine and areas to the east. This paper attempts to outline, in the simplest manner, the geological and structural evolution of the main gold-producing region of the Barberton Goldfield. The principal aim is therefore to highlight the structural influence of the diapiric plutonism and the manner in which the plutons contributed significantly to the horizontal reactivation of pre-existing regional faults, which in turn, resulted in the progressive deformation of a heterogeneous lithological terrane.

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DEFORMATIONS AND THE SEQUENCE OF THE STRUCTURES FORMATION IN THE NORTHERN PART OF THE ZONE OF DEVELOPMENT OF MAKSUTOVO METAMORPHIC COMPLEX (SOUTHERN URALS)

Proceedings of higher educational establishments Geology and Exploration ◽

10.32454/0016-7762-2018-1-17-26 ◽

2018 ◽

pp. 17-26

Author(s):

B. G. Golionko ◽

A. V. Ryazantsev

Keyword(s):

Structural Evolution ◽

Southern Urals ◽

Strike Slip ◽

Metamorphic Rocks ◽

Metamorphic Complex ◽

The Third ◽

Deformation Stage ◽

Third Stage ◽

Western Border ◽

Definition Of

Composition and structural evolution of the Maksutovo metamorphic complex in the its northern part has been examined. The early folds 77) plunging in the SE direction have been established to be developed only in the rocks of the Maksutovo metamorphic complex. The problem of the definition of the geodynamic nature of the 7Л deformation stage, marked by the folds 77), has not been solved yet. Tectonic inclusions of the metamorphic rocks adjacent to the western border of the Main Uralian Thrust without traces of 7Л deformation stage must not be considered as parts of the Maksutovo metamorphic complex. 7Л1 deformation stage expressed in formation of thrusts and 77. west vergent folds is connected with late Paleozoic continental collision. The third stage of deformation 7JIII is marked by development of 77) folds with steep hinges associated with post collision strike slip movements

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Rift evolution and structural style in the Orphan Basin: results from regional structural restorations and crustal area balancing

10.5194/egusphere-egu21-6527 ◽

2021 ◽

Author(s):

Adam J. Cawood ◽

David A. Ferrill ◽

Alan P. Morris ◽

David Norris ◽

David McCallum ◽

...

Keyword(s):

Cross Sections ◽

Seismic Data ◽

Large Scale ◽

Structural Evolution ◽

Strike Slip ◽

Detachment Faults ◽

The North ◽

Structural Style ◽

Complex Structural ◽

Structural Configurations

The Orphan Basin on the eastern edge of the Newfoundland continental margin formed as a Mesozoic rift basin prior to continental breakup associated with the opening of the North Atlantic. Few exploration wells exist in the basin, and until recently regional interpretations have been based on sparse seismic data coverage - because of this the structural evolution of the Orphan Basin has historically not been well understood. Key uncertainties include the timing and amount of rift-related extension, dominant extension directions, and the structural styles that accommodated progressive rift development in the basin. &#160;&#160;&#160;&#160;Interpretation of newly acquired modern broadband seismic data and structural restoration of three regional, WNW-ESE oriented cross-sections across the Orphan Basin and Flemish Cap provide new insights into rift evolution and structural style in the area. Our results show that major extension in the basin occurred between 167 Ma and 135 Ma, with most extension occurring prior to 151 Ma. We show that extension after 135 Ma largely occurred east of Flemish Cap due to a shift in the locus of rifting from the Orphan Basin to east of Flemish Cap. We find no evidence for discrete rifting events in the Orphan Basin, as has been suggested by other authors.&#160; Kinematic restoration and associated heave measurements for the Orphan Basin show that extension was both widespread and relatively evenly distributed across the basin from Middle-Late Jurassic to Early Cretaceous.We provide evidence for more widespread deposition of Jurassic strata throughout the Orphan Basin than previously interpreted, and show that Jurassic deposition was controlled by the occurrence and displacement of crustal-scale extensional detachment faults. &#160;Structure in the three regional cross sections is dominated by large-scale, shallowly dipping extensional detachment faults. These faults mainly dip to the northwest and control the geometry and position of extensional basins &#8211; grabens and half-grabens &#8211; which occur at a range of scales. Stacked detachment surfaces, hyperextension, and attenuation of the crust are observed in central and eastern parts of the Orphan Basin. Zones of extreme crustal attenuation (to ca. 3.7 km) are interpreted to be coincident with large-displacement (up to 60 km) low-angle detachments. Results from crustal area balancing suggest that up to 41% of extension is not recognized through structural seismic interpretation, which we attribute to subseismic-scale ductile and brittle deformation, and uncertainties in the identification of detachment surfaces or complex structural configurations (e.g., overprinting of early extensional deformation).Rifting style in the central, northern, and eastern parts of the Orphan Basin is dominated by low-angle detachment faulting with maximum extension perpendicular to the incipient rift axis. In contrast, structural geometries in the southwestern part of the basin are suggestive of transtensional deformation, and interplay of normal and strike-slip faulting.&#160; Results from map-based interpretation show that strike-slip faults within this transtensional zone are associated with displacement transfer between half-grabens of opposing polarity, rather than regional strike-slip displacement.&#160; These structures are interpreted as contemporaneous and kinematically linked to displacement along low-angle detachment surfaces elsewhere, and are not attributed to distinct episodes of oblique extension.&#160; &#160;&#160;&#160;&#160;&#160;

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