The structural evolution of pull-apart basins in response to relative plate rotations; A physical analogue modelling case study from the Northern Gulf of California.

2020 ◽  
Author(s):  
Georgios-Pavlos Farangitakis ◽  
Kenneth J.W. McCaffrey ◽  
Ernst Willingshofer ◽  
Lara M. Kalnins ◽  
Jeroen van Hunen ◽  
...  
Keyword(s):  
Gulf Of California ◽  
Motion Vector ◽  
Structural Evolution ◽  
Strike Slip ◽  
Plate Motion ◽  
Extension Rate ◽  
Sediment Distribution ◽  
Pull Apart Basin ◽  
Analogue Modelling ◽  
Extension Direction

<p>Pull-apart basins are structural features closely linked to the interactions between strike-slip and extensional tectonics. Their morphology and structural evolution are determined by factors such as extension rate, width/length ratio, or changes in the extension direction. In this work, we focus on changes in extension direction during the formation of a pull-apart basin as a basis to further understand the evolution of the northern Gulf of California through a series of physical analogue modelling experiments.</p><p>We investigate the effect of a variation in the basin extension direction, using a two-layer ductile-brittle configuration to simulate continental crust rheology. Pull-apart basin development is accomplished by displacing a plastic sheet at the bottom of the experiment, with pre-cut geometry resembling interconnected rift and strike-slip segments, orthogonal to the evolving rift axes. Subsequently, we change the relative motion of the base plate by 7<sup>o</sup> in accordance with the reconstructed plate vector from the Gulf of California. Oblique extension continues on this new plate motion vector to the end of the experiment.</p><p>To analyse the results, we inserted the model cross-sections in a seismic interpretation software generating 3D interpretations for faulting and sedimentary thickness. Preliminary results show that the shift in the direction of plate motion produces sigmoidal oblique slip faults that become normal when deformation adjusts to the new plate motion vector. Furthermore, it appears that sediment distribution is controlled heavily by the relative plate rotation.</p><p>Finally, we compare our observations with seismic reflection images, sedimentary package thicknesses and fault interpretations from the pull-apart structure in the Northern Gulf of California transtensional margin, where we find good agreement between model and nature.</p>

scholarly journals Looking beyond kinematics: 3D thermo-mechanical modelling reveals the dynamics of transform margins

Solid Earth ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 1211-1232
Author(s):  
Anthony Jourdon ◽  
Charlie Kergaravat ◽  
Guillaume Duclaux ◽  
Caroline Huguen
Keyword(s):  
Boundary Conditions ◽  
Strain Localization ◽  
Numerical Models ◽  
Motion Vector ◽  
Shear Zones ◽  
Strike Slip ◽  
Plate Motion ◽  
Plate Boundaries ◽  
Mechanical Modelling ◽  
Extension Direction

Abstract. Transform margins represent ∼ 30 % of non-convergent margins worldwide. Their formation and evolution have traditionally been addressed through kinematic models that do not account for the mechanical behaviour of the lithosphere. In this study, we use high-resolution 3D numerical thermo-mechanical modelling to simulate and investigate the evolution of intra-continental strain localization under oblique extension. The obliquity is set through velocity boundary conditions that range from 15∘ (high obliquity) to 75∘ (low obliquity) every 15∘ for rheologies of strong and weak lower continental crust. Numerical models show that the formation of localized strike-slip shear zones leading to transform continental margins always follows a thinning phase during which the lithosphere is thermally and mechanically weakened. For low- (75∘) to intermediate-obliquity (45∘) cases, the strike-slip faults are not parallel to the extension direction but form an angle of 20∘ to 40∘ with the plate motion vector, while for higher obliquities (30∘ to 15∘) the strike-slip faults develop parallel to the extension direction. Numerical models also show that during the thinning of the lithosphere, the stress and strain re-orient while boundary conditions are kept constant. This evolution, due to the weakening of the lithosphere, leads to a strain localization process in three major phases: (1) initiation of strain in a rigid plate where structures are sub-perpendicular to the extension direction; (2) distributed deformation with local stress field variations and formation of transtensional and strike-slip structures; (3) formation of highly localized plate boundaries stopping the intra-continental deformation. Our results call for a thorough re-evaluation of the kinematic approach to studying transform margins.

scholarly journals Structural analysis of the Rio Preto fold belt (northwestern Bahia / southern Piauí), a doubly-vergent asymmetric fan developed during the Brasiliano Orogeny

2014 ◽  
Vol 86 (3) ◽  
pp. 1101-1113 ◽  
Author(s):  
FABRÍCIO A. CAXITO ◽  
ALEXANDRE UHLEIN ◽  
LUIZ F.G. MORALES ◽  
MARCOS EGYDIO-SILVA ◽  
JULIO C.D. SANGLARD ◽  
...  
Keyword(s):  
Structural Analysis ◽  
Structural Evolution ◽  
Shear Zones ◽  
Central Compartment ◽  
Strike Slip ◽  
Fold Belt ◽  
Main Structure ◽  
The North ◽  
Brasiliano Orogeny ◽  
Analog Models

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.

Late Pleistocene extension and strike-slip in the Dead Sea Basin

2004 ◽  
Vol 141 (5) ◽  
pp. 565-572 ◽  
Author(s):  
YUVAL BARTOV ◽  
AMIR SAGY
Keyword(s):  
Internal Structure ◽  
Slip Rate ◽  
Dead Sea ◽  
Strike Slip ◽  
Normal Faults ◽  
Small Scale ◽  
Dead Sea Basin ◽  
Pull Apart Basin ◽  
Western Border ◽  
The Dead

A newly discovered active small-scale pull-apart (Mor structure), located in the western part of the Dead Sea Basin, shows recent basin-parallel extension and strike-slip faulting, and offers a rare view of pull-apart internal structure. The Mor structure is bounded by N–S-trending strike-slip faults, and cross-cut by low-angle, E–W-trending normal faults. The geometry of this pull-apart suggests that displacement between the two stepped N–S strike-slip faults of the Mor structure is transferred by the extension associated with the normal faults. The continuing deformation in this structure is evident by the observation of at least three deformation episodes between 50 ka and present. The calculated sinistral slip-rate is 3.5 mm/yr over the last 30 000 years. This slip rate indicates that the Mor structure overlies the currently most active strike-slip fault within the western border of the Dead Sea pull-apart. The Mor structure is an example of a small pull-apart basin developed within a larger pull-apart. This type of hierarchy in pull-apart structures is an indication for their ongoing evolution.

scholarly journals Looking beyond kinematics: 3D thermo-mechanical modelling reveals the dynamic of transform margins

2021 ◽  
Author(s):  
Anthony Jourdon ◽  
Charlie Kergaravat ◽  
Guillaume Duclaux ◽  
Caroline Huguen
Keyword(s):  
Boundary Conditions ◽  
Strain Localization ◽  
Numerical Models ◽  
Local Stress ◽  
Shear Zones ◽  
Strike Slip ◽  
Convergent Margins ◽  
Mechanical Modelling ◽  
Kinematic Models ◽  
Extension Direction

Abstract. Transform margins represent ~30 % of the non-convergent margins worldwide. Their formation and evolution have long been addressed through kinematic models that do not account for the mechanical behaviour of the lithosphere. In this study, we use high resolution 3D numerical thermo-mechanical modelling to simulate and investigate the evolution of the intra-continental strain localization under oblique extension. The obliquity is set through velocity boundary conditions that range from 15° (high obliquity) to 75° (low obliquity) every 15° for strong and weak lower continental crust rheologies. Numerical models show that the formation of localized strike-slip shear zones leading to transform continental margins always follows a thinning phase during which the lithosphere is thermally and mechanically weakened. For low (75°) to intermediate (45°) obliquity cases, the strike-slip faults are not parallel to the extension direction but form an angle of 20° to 40° with the plates' motion while for higher obliquities (30° to 15°) the strike-slip faults develop parallel to the extension direction. Numerical models also show that during the thinning of the lithosphere, the stress and strain re-orient while boundary conditions are kept constant. This evolution, due to the weakening of the lithosphere, leads to a strain localization process in three major phases: (1) strain initiates in a rigid plate where structures are sub-perpendicular to the extension direction; (2) distributed deformation with local stress field variations and formation of transtensional and strike-slip structures; (3) formation of highly localized plates boundaries stopping the intra-continental deformation. Our results call for a thorough re-evaluation of the kinematic approach to studying transform margins.

scholarly journals Stretching and Contraction of Extensional Basins With Pre-Rift Salt: A Numerical Modeling Approach

2021 ◽  
Vol 9 ◽  
Author(s):  
Pablo Granado ◽  
Jonas B. Ruh ◽  
Pablo Santolaria ◽  
Philipp Strauss ◽  
Josep Anton Muñoz
Keyword(s):  
Hanging Wall ◽  
Structural Evolution ◽  
Extension Rate ◽  
Rift Basins ◽  
Basin Inversion ◽  
Accommodation Space ◽  
Basement Faults ◽  
Original Distribution ◽  
Thrust Belts ◽  
Half Graben

We present a series of 2D thermo-mechanical numerical experiments of thick-skinned crustal extension including a pre-rift salt horizon and subsequent thin-, thick-skinned, or mixed styles of convergence accompanied by surface processes. Extension localization along steep basement faults produces half-graben structures and leads to variations in the original distribution of pre-rift salt. Thick-skinned extension rate and salt rheology control hanging wall accommodation space as well as the locus and timing of minibasin grounding. Upon shortening, extension-related basement steps hinder forward propagation of evolving shallow thrust systems; conversely, if full basin inversion takes place along every individual fault, the regional salt layer is placed back to its pre-extensional configuration, constituting a regionally continuous décollement. Continued shortening and basement involvement deform the shallow fold-thrust structures and locally breaches the shallow décollement. We aim at obtaining a series of structural, stratigraphic and kinematic templates of fold-and-thrust belts involving rift basins with an intervening pre-rift salt horizon. Numerical results are compared to natural cases of salt-related inversion tectonics to better understand their structural evolution.

scholarly journals Study on the relationship between multi-stage strike-slip mechanism and basin evolution in Fangzheng fault depression

2018 ◽  
Vol 22 (4) ◽  
pp. 335-339
Author(s):  
Jingfeng Wu ◽  
Qi'an Meng ◽  
Xiaofei Fu ◽  
Yuling Ma ◽  
Meifeng Sun ◽  
...  
Keyword(s):  
Seismic Data ◽  
Structural Characteristics ◽  
Stage Structure ◽  
Tectonic Stress ◽  
Strike Slip ◽  
The West ◽  
Lateral Strike Slip ◽  
Slip Mechanism ◽  
Pull Apart Basin ◽  
Multi Stage

Fangzheng fault depression is controlled by the northern of the Tan-Lu fault zone. It undergoes multi-stage strike-slip, extrusion modification, and erosion of the thermal uplift, forming a tectonic pattern of uplifts connected with sags. Through the regional dynamic analysis, the study of the activity law of the western Pacific plate has clarified the formation and transformation of the regional tectonic stress field. Under the background of the multi-stage of the strike-slip mechanism in the northern part of the Tan-lu fault, the Fangzheng fault depression has a characteristic of the “left-lateral strike-slip pull-apart basin, right-lateral strike-slip extrusion transformation.” According to the difference of the strike-slip, the Fangzheng fault depression has divided into two parts: the East fault depression and the West fault depression. The seismic data, seismic attribute analysis, and geological modeling techniques have applied to analyze the two fault depressions, the East fault depression has actively controlled by the strike-slip activity, and the structure is complex. The seismic data quality is poor; the structure of the West Fault Depression is the opposite and structural characteristics of asymmetrical difference strike-slip in the East and West fault depressions. Interpretation of seismic sections through a slippery background, the strike-slip attributes of the whole fault depression from south to north are segmented, and the strike-slip mechanism from east to west is different. Under the control of the multi-stage strike-slip mechanism, the Fangzheng fault depression is divided into six stages of strike-slip evolution, corresponding to the six different stages of the strike-slip control basin, the formation process of the asymmetric difference strike-slip fault basin is clarified, which provides a reference for the study of the strike-slip pull-apart basin with multi-stage structure.

scholarly journals Breaching of strike-slip faults and successive flooding of pull-apart basins to form the Gulf of California seaway from ca. 8–6 Ma

Geology ◽  
2018 ◽  
Vol 46 (8) ◽  
pp. 695-698 ◽  
Author(s):  
Paul J. Umhoefer ◽  
Michael H. Darin ◽  
Scott E. K. Bennett ◽  
Lisa A. Skinner ◽  
Rebecca J. Dorsey ◽  
...  
Keyword(s):  
Gulf Of California ◽  
Strike Slip

scholarly journals Triple junction kinematics accounts for the 2016 Mw7.8 Kaikoura earthquake rupture complexity

2019 ◽  
Vol 116 (52) ◽  
pp. 26367-26375 ◽  
Author(s):  
Xuhua Shi ◽  
Paul Tapponnier ◽  
Teng Wang ◽  
Shengji Wei ◽  
Yu Wang ◽  
...  
Keyword(s):  
New Zealand ◽  
Triple Junction ◽  
Large Scale ◽  
Strike Slip ◽  
Plate Motion ◽  
Fault System ◽  
Coseismic Deformation ◽  
Coseismic Slip ◽  
Slab Geometry ◽  
Kaikoura Earthquake

The 2016, moment magnitude (Mw) 7.8, Kaikoura earthquake generated the most complex surface ruptures ever observed. Although likely linked with kinematic changes in central New Zealand, the driving mechanisms of such complexity remain unclear. Here, we propose an interpretation accounting for the most puzzling aspects of the 2016 rupture. We examine the partitioning of plate motion and coseismic slip during the 2016 event in and around Kaikoura and the large-scale fault kinematics, volcanism, seismicity, and slab geometry in the broader Tonga–Kermadec region. We find that the plate motion partitioning near Kaikoura is comparable to the coseismic partitioning between strike-slip motion on the Kekerengu fault and subperpendicular thrusting along the offshore West–Hikurangi megathrust. Together with measured slip rates and paleoseismological results along the Hope, Kekerengu, and Wairarapa faults, this observation suggests that the West–Hikurangi thrust and Kekerengu faults bound the southernmost tip of the Tonga–Kermadec sliver plate. The narrow region, around Kaikoura, where the 3 fastest-slipping faults of New Zealand meet, thus hosts a fault–fault–trench (FFT) triple junction, which accounts for the particularly convoluted 2016 coseismic deformation. That triple junction appears to have migrated southward since the birth of the sliver plate (around 5 to 7 million years ago). This likely drove southward stepping of strike-slip shear within the Marlborough fault system and propagation of volcanism in the North Island. Hence, on a multimillennial time scale, the apparently distributed faulting across southern New Zealand may reflect classic plate-tectonic triple-junction migration rather than diffuse deformation of the continental lithosphere.

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