Geometry and timing of strike-slip and normal faults in the northern Walker Lane, northwestern Nevada and northeastern California: Strain partitioning or sequential extensional and strike-slip deformation?

The Carpatho-Balkanides of south-eastern Europe is a double 180&#176; curved orogenic system. It is comprised of a foreland-convex orocline, situated in the north and east and a backarc-convex orocline situated in the south and west. The southern orocline of the Carpatho-Balkanides orogen formed during the Cretaceous closure of the Alpine Tethys Ocean and collision of the Dacia mega-unit with the Moesian Platform. Following the main orogen-building processes, the Carpathians subduction and Miocene slab retreat in the West and East Carpathians have driven the formation of the backarc-convex oroclinal bending in the south and west. The orocline formed during clockwise rotation of the Dacia mega-unit and coeval docking against the Moesian indenter. This oroclinal bending was associated with a Paleocene-Eocene orogen-parallel extension that exhumed the Danubian nappes of the South Carpathians and with a large late Oligocene &#8211; middle Miocene Circum-Moesian fault system that affected the orogenic system surrounding the Moesian Platform along its southern, western and northern margins. This fault system is composed of various segments that have different and contrasting types of kinematics, which often formed coevally, indicating a large degree of strain partitioning during oroclinal bending. It includes the curved Cerna and Timok faults that cumulate up to 100 km of dextral offset, the lower offset Sokobanja-Zvonce and Rtanj-Pirot dextral strike-slip faults, associated with orogen parallel extension that controls numerous intra-montane basins and thrusting of the western Balkans units over the Moesian Platform. We have performed a field structural study in order to understand the mechanisms of deformation transfer and strain partitioning around the Moesian indenter during oroclinal bending by focusing on kinematics and geometry of large-scale faults within the Circum-Moesian fault system.Our structural analysis shows that the major strike-slip faults are composed of multi-strand geometries associated with significant strain partitioning within tens to hundreds of metres wide deformation zones. Kinematics of the Circum-Moesian fault system changes from transtensional in the north, where the formation of numerous basins is controlled by the Cerna or Timok faults, to strike-slip and transpression in the south, where transcurrent offsets are gradually transferred to thrusting in the Balkanides. The characteristic feature of the whole system is splaying of major faults to facilitate movements around the Moesian indenter. Splaying towards the east connects the Circum-Moesian fault system with deformation observed in the Getic Depression in front of the South Carpathians, while in the south-west the Sokobanja-Zvonce and Rtanj-Pirot faults splay off the Timok Fault. These two faults are connected by coeval E-W oriented normal faults that control several intra-montane basins and accommodate orogen-parallel extension. We infer that all these deformations are driven by the roll-back of the Carpathians slab that exerts a northward pull on the upper Dacia plate in the Serbian Carpathians. However, the variability in deformation styles is controlled by geometry of the Moesian indenter and the distance to Moesia, as the rotation and northward displacements increase gradually to the north and west.

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Fracture networks and strike–slip deformation along reactivated normal faults in Quaternary travertine deposits, Denizli Basin, western Turkey

Tectonophysics ◽

10.1016/j.tecto.2012.12.018 ◽

2013 ◽

Vol 588 ◽

pp. 154-170 ◽

Cited By ~ 40

Author(s):

Koen Van Noten ◽

Hannes Claes ◽

Jeroen Soete ◽

Anneleen Foubert ◽

Mehmet Özkul ◽

...

Keyword(s):

Strike Slip ◽

Normal Faults ◽

Fracture Networks ◽

Western Turkey ◽

Slip Deformation

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Neogene kinematics and structural evolution of the Giudicarie Belt and eastern Southern Alpine orogenic front (Northern Italy)

10.5194/egusphere-egu2020-7840 ◽

2020 ◽

Author(s):

Vincent Verwater ◽

Mark R. Handy ◽

Eline Le Breton ◽

Vincenzo Picotti ◽

Azam Jozi Najafabadi ◽

...

Keyword(s):

Cross Sections ◽

Hanging Wall ◽

Structural Evolution ◽

Leading Edge ◽

Strike Slip ◽

Southern Alps ◽

Normal Faults ◽

Strain Partitioning ◽

The North ◽

Thickness Variations

The eastern Southern Alps are part of the deformed leading edge of the Adriatic plate indenting the European plate to the north. Neogene deformation in the eastern Southern Alps is partitioned into three, kinematically linked fold-and-fault systems: (1) The Giudicarie Belt, (2) the Valsugana Thrust System and (3) the external fold-and-thrust systems of the orogenic front, including the strike-slip Schio-Vicenza Fault. We aim to constrain fault kinematics from the Southern Alpine orogenic front to the Northern Giudicarie Fault to better understand deformation of the Adriatic indenter since Miocene time.The Giudicarie Belt is a sinistral transverse zone characterized by NNE-oriented faults. Some of these faults originated in the Mesozoic as NNE-SSW trending normal faults, which were inverted during Alpine orogeny. Most of the Mesozoic normal faults are oriented oblique to sub-parallel to the main Neogene shortening direction, which led to strain partitioning between thrust and strike-slip faults. This significant strike-slip component complicates kinematic and structural restoration of geological cross-sections in 2-D because rock units moved into and out of the section trace, distorting in-section shortening estimates.To assess lateral variations in shortening and quantify strain partitioning along and across the strike of the Giudicarie Belt, we constructed and balanced a network of closely spaced cross-sections perpendicular to the main structural trend. Seven 2-D NNW-SSE cross-sections from the Northern Giudicarie Fault to the Southern Alpine orogenic front reveal that the amount of Neogene NNW-SSE shortening varies from 11 km in the vicinity of the Adige embayment to 27 km further NE, with most shortening (20 to 26 km) accommodated within the Valsugana and Giudicarie systems. Shortening differs on either side of the Trento-Cles, Schio-Vicenza (4 km difference) and Ballino-Garda (7 km difference) strike-slip faults. These faults are inherited Mesozoic faults that coincide with significant stratigraphic thickness variations, which we constrained along orogen-parallel cross-sections. The SW-NE variation in shortening is inferred to have been taken up by these sinistral strike-slip faults, but also including the Northern Giudicarie Fault, for which we estimate the minimum amount of slip to be 19 km.Exposure of Pre-Permian basement in the hanging wall of thrusts indicates a thick-skinned style of deformation. Forward modelling using the MOVE Suite Software indicates that the depth of the detachments within the Pre-Permian basement is no greater than 20 km. A recently located cluster of minor seismic events (2017-2018) within the study area is aligned between 5 and 15 km along the modelled detachments. These earthquake clusters occur within the external fold-and-thrust systems of the orogenic front, suggesting that ongoing shortening is taken up within this system and that the Valsugana and Giudicarie systems are inactive today.

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Neogene-to-Quaternary post-orogenic tectonic evolution and CaCO3-rich fluids from the Tabernas basin (eastern Betics, Spain) reveal control by deep-seated processes in the mantle

10.5194/egusphere-egu2020-9221 ◽

2020 ◽

Author(s):

Marine Larrey ◽

Frédéric Mouthereau ◽

Emmanuel Masini ◽

Sylvain Calassou ◽

Aurélien Virgone ◽

...

Keyword(s):

Strike Slip ◽

Normal Faults ◽

Structural Constraints ◽

Strain Partitioning ◽

Plate Convergence ◽

Crustal Thinning ◽

Calcite Veins ◽

Show Evidence ◽

Continental Carbonates ◽

Parallel Extension

Since Miocene times, the crustal thinning in eastern Betics and the Alboran region associated with westward slab retreat led to the formation and exhumation of metamorphic domes and EW-directed narrow basins.The Tabernas basin preserves a sedimentary records of the last stages of metamorphic domes exhumation (14 to 8 Ma). Structural constraints from fault patterns and sedimentary archives show evidence in the field for E-W strike-slip faults that developed close to dome-basin contacts. The evolution of strike-slip faulting and extensional basins reveals strain partitioning during the late Miocene that is consistent with the present-day regional NNW-directed compression and WSW-directed/orogen-parallel extension that result from the NW-SE Africa-Europe plate convergence. A regional cross-section further emphasizes the role of crustal-scale strike-slip faulting and slab detachment and delamination under the Alboran domain.Calcite veins that developed during the orogen-parallel extension in the metamorphic basement and the Tortonian sedimentary rocks show a wide variety of stable isotopes ratios. Calcite cements have &#948;18O values ranging from -17.23&#8240; to -5.30&#8240; for, and from -15.77&#8240; to -1.6&#8240; for &#948;13C isotopic ratios. This patterns is interpreted to reflect the increase of freshwater input buffered by the composition of host carbonate rocks.Continental carbonates of Quaternary ages are widespread in the Tabernas basin. Travertines show a close structural relationship with N170 and N50 normal faults, implying tectonically-controlled Ca/CO2 leakages. Their &#948;13C values are compatible with a hydrothermal origin from a deep-seated carbon source (&#948;18O median of -7.5&#8240;, &#948;13C median of 2.1&#8240;). Degassing associated with regional volcanism from the Serravallian until the Tortonian-Messinian ages is likely to be also the main vector of recent CO2 storages in rocks. The U-Th ages of travertines, ranging from 8ka &#177; 0.2 to 354ka &#177;76, further outline interactions with captive aquifer from 350ka and subsequent Ca/CO2 leakages due to geodynamic changes.

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The 25 October, 2018 Zakynthos (Greece) earthquake: seismic activity at the transition between a transform fault and a subduction zone.

Geophysical Journal International ◽

10.1093/gji/ggaa575 ◽

2020 ◽

Author(s):

P Papadimitriou ◽

V Kapetanidis ◽

A Karakonstantis ◽

I Spingos ◽

K Pavlou ◽

...

Keyword(s):

Spatial Clustering ◽

Accretionary Prism ◽

Velocity Model ◽

Strike Slip ◽

Double Difference ◽

Strain Partitioning ◽

Transform Fault ◽

Fault Plane Solutions ◽

The North ◽

Waveform Modelling

Summary The properties of the Mw = 6.7 earthquake that took place on 25 October 2018, 22:54:51 UTC, ∼50 km SW of the Zakynthos Island, Greece, are thoroughly examined. The main rupture occurred on a dextral strike-slip, low-angle, east-dipping fault at a depth of 12 km, as determined by teleseismic waveform modelling. Over 4000 aftershocks were manually analysed for a period of 158 days. The events were initially located with an optimal 1D velocity model and then relocated with the double-difference method to reveal details of their spatial distribution. The latter spreads in an area spanning 80 km NNW-SSE and ∼55 km WSW-ENE. Certain parts of the aftershock zone present strong spatial clustering, mainly to the north, close to Zakynthos Island, and at the southernmost edge of the sequence. Focal mechanisms were determined for 61 significant aftershocks using regional waveform modelling. The results revealed characteristics similar to the mainshock, with few aftershocks exhibiting strike-slip faulting at steeper dip angles, possibly related to splay faults on the accretionary prism. The slip vectors that correspond to the east-dipping planes are compatible with the long-term plate convergence and with the direction of coseismic displacement on the Zakynthos Island. Fault-plane solutions in the broader study area were inverted for the determination of the regional stress-field. The results revealed a nearly horizontal, SW-NE to E-W-trending S1 and a more variable S3 axis, favouring transpressional tectonics. Spatial clusters at the northern and southern ends of the aftershock zone coincide with the SW extension of sub-vertical along-dip faults of the segmented subducting slab. The mainshock occurred in an area where strike-slip tectonics, related to the Cephalonia Transform Fault and the NW Peloponnese region, gradually converts into reverse faulting at the western edge of the Hellenic subduction. Plausible scenarios for the 2018 Zakynthos earthquake sequence include a rupture on the subduction interface, provided the slab is tilted eastwards in that area, or the reactivation of an older east-dipping thrust as a low-angle strike-slip fault that contributes to strain partitioning.

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Rampart seismic zone of central Alaska

Bulletin of the Seismological Society of America ◽

10.1785/bssa0730030813 ◽

1983 ◽

Vol 73 (3) ◽

pp. 813-829

Author(s):

P. Yi-Fa Huang ◽

N. N. Biswas

Keyword(s):

Main Shock ◽

Fault Plane ◽

B Value ◽

Aftershock Sequence ◽

Strike Slip ◽

Lithospheric Plate ◽

Normal Faults ◽

Seismic Zone ◽

The West ◽

Fault Plane Solutions

abstract This paper describes the characteristics of the Rampart seismic zone by means of the aftershock sequence of the Rampart earthquake (ML = 6.8) which occurred in central Alaska on 29 October 1968. The magnitudes of the aftershocks ranged from about 1.6 to 4.4 which yielded a b value of 0.96 ± 0.09. The locations of the aftershocks outline a NNE-SSW trending aftershock zone about 50 km long which coincides with the offset of the Kaltag fault from the Victoria Creek fault. The rupture zone dips steeply (≈80°) to the west and extends from the surface to a depth of about 10 km. Fault plane solutions for a group of selected aftershocks, which occurred over a period of 22 days after the main shock, show simultaneous occurrences of strike-slip and normal faults. A comparison of the trends in seismicity between the neighboring areas shows that the Rampart seismic zone lies outside the area of underthrusting of the lithospheric plate in southcentral and central Alaska. The seismic zone outlined by the aftershock sequence appears to represent the formation of an intraplate fracture caused by regional northwest compression.

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Alternating asymmetric topography of the Alaska range along the strike-slip Denali fault: Strain partitioning and lithospheric control across a terrane suture zone

Tectonics ◽

10.1002/2013tc003432 ◽

2014 ◽

Vol 33 (8) ◽

pp. 1519-1533 ◽

Cited By ~ 29

Author(s):

Paul G. Fitzgerald ◽

Sarah M. Roeske ◽

Jeffery A. Benowitz ◽

Steven J. Riccio ◽

Stephanie E. Perry ◽

...

Keyword(s):

Strike Slip ◽

Suture Zone ◽

Strain Partitioning ◽

Alaska Range ◽

Denali Fault

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

Geological Magazine ◽

10.1017/s001675680400963x ◽

2004 ◽

Vol 141 (5) ◽

pp. 565-572 ◽

Cited By ~ 25

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.

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