Flexural strike-slip basins

Strike-slip faults are classically associated with pull-apart basins where continental crust is thinned between two laterally offset fault segments. We propose a subsidence mechanism to explain the formation of a new type of basin where no substantial segment offset or syn-strike-slip thinning is observed. Such “flexural strike-slip basins” form due to a sediment load creating accommodation space by bending the lithosphere. We use a two-way coupling between the geodynamic code ASPECT and surface-processes code FastScape to show that flexural strike-slip basins emerge if sediment is deposited on thin lithosphere close to a strike-slip fault. These conditions were met at the Andaman Basin Central fault (Andaman Sea, Indian Ocean), where seismic reflection data provide evidence of a laterally extensive flexural basin with a depocenter located parallel to the strike-slip fault trace.

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Flexural strike-slip basins

10.31223/x54c8g ◽

2021 ◽

Author(s):

Derek Neuharth ◽

Sascha Brune ◽

Anne Glerum ◽

Chris Morley ◽

Xiaoping Yuan ◽

...

Keyword(s):

Seismic Reflection ◽

Sediment Load ◽

Strike Slip ◽

Strike Slip Fault ◽

Surface Processes ◽

Seismic Reflection Data ◽

Accommodation Space ◽

Reflection Data ◽

New Type ◽

Fault Trace

Strike-slip faults are classically associated with pull-apart basins where continental crust is thinned between two laterally offset fault segments. Here we propose a subsidence mechanism to explain the formation of a new type of basin where no substantial segment offset or syn-strike-slip thinning is observed. Such “flexural strike-slip basins” form due to a sediment load creating accommodation space by bending the lithosphere. We use a two-way coupling between the geodynamic code ASPECT and surface processes code FastScape to show that flexural strike-slip basins emerge if sediment is deposited on thin lithosphere close to a strike-slip fault. These conditions were met at the Andaman Basin Central Fault, where seismic reflection data provide evidence of a laterally extensive flexural basin with a depocenter located parallel to the strike-slip fault trace.

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Strike-slip tectonics and development of the Tertiary Queen Charlotte Basin, offshore western Canada: evidence from seismic reflection data

Basin Research ◽

10.1111/j.1365-2117.1992.tb00039.x ◽

1992 ◽

Vol 4 (1) ◽

pp. 1-20 ◽

Cited By ~ 56

Author(s):

K. M. M. Rohr ◽

J. R. Dietrich

Keyword(s):

Seismic Reflection ◽

Strike Slip ◽

Western Canada ◽

Seismic Reflection Data ◽

Reflection Data

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Shallow Seismic Reflection Survey of the Bootheel Lineament Area, Southeastern Missouri

Seismological Research Letters ◽

10.1785/gssrl.63.3.285 ◽

1992 ◽

Vol 63 (3) ◽

pp. 285-295 ◽

Cited By ~ 17

Author(s):

Eugene S. Schweig ◽

Fan Shen ◽

Lisa R. Kanter ◽

Eugene A. Luzietti ◽

Roy B. VanArsdale ◽

...

Keyword(s):

Seismic Reflection ◽

Strike Slip ◽

Seismic Reflection Data ◽

Reflection Data ◽

Shallow Seismic ◽

Slip Deformation ◽

Flower Structures

Abstract During 1990 we collected eight lines (11.5 km) of shallow seismic reflection data across the Bootheel lineament, a discontinuous feature that extends about 135 km in a north-northeast direction through northeastern Arkansas and southeastern Missouri. The profiles image reflectors at depths between about 55 m to 800 m. Gentle folding with wavelengths of about 800 m and amplitudes of 10 m to 25 m is evident on nearly every profile, generally coinciding with the surface traces of the lineament. We interpret our lines to show a complex zone of strike-slip deformation consisting of multiple flower structures, with deformation at least as young as the Eocene/Quaternary unconformity.

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Convergent strike-slip across the Dead Sea Fault in northern Israel, imaged by high-resolution seismic reflection data

Israel Journal of Earth Sciences ◽

10.1560/ijes.58.3-4.203 ◽

2009 ◽

Vol 58 (3) ◽

pp. 203-216 ◽

Cited By ~ 6

Author(s):

Ram Weinberger ◽

Uri Schattner ◽

Benjamin Medvedev ◽

Uri Frieslander ◽

Amihai Sneh ◽

...

Keyword(s):

High Resolution ◽

Seismic Reflection ◽

Dead Sea ◽

Strike Slip ◽

Seismic Reflection Data ◽

Reflection Data ◽

The Dead

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Seismic reflection profiles across the central Kapuskasing uplift

Canadian Journal of Earth Sciences ◽

10.1139/e94-092 ◽

1994 ◽

Vol 31 (7) ◽

pp. 1016-1026 ◽

Cited By ~ 8

Author(s):

Alain D. Leclair ◽

John A. Percival ◽

Alan G. Green ◽

Jianjun Wu ◽

Gordon F. West ◽

...

Keyword(s):

Seismic Reflection ◽

Normal Fault ◽

Strike Slip ◽

Gravity Models ◽

Seismic Reflection Data ◽

Reflection Data ◽

Reflection Geometry ◽

Major Strike ◽

Seismic Sections ◽

Seismic Reflection Profiles

The central Superior Province is transected by the intracratonic Kapuskasing uplift, which contains rocks exhumed from 30 to 35 km paleodepth. As part of the Lithoprobe Kapuskasing transect, approximately 52 km of 16 s seismic reflection data were collected in the central segment of the uplift along three profiles that traverse the northern Groundhog River block, the bounding Saganash Lake fault, and the eastern Val Rita block. The seismic sections have the following characteristics in common: (i) a complexly reflective uppermost portion (< 1 s) limiting correlation of reflective zones and surface features; (ii) numerous subhorizontal, east- and west-dipping reflection zones; and (iii) a significant reduction in reflectivity beyond the refraction-defined Moho (~ 14 s). Beneath the Groundhog River block a series of straight, west-dipping (~ 20°) reflection zones between 2 and 10 s is underlain by subhorizontal reflections in the lower crust. Across the Saganash Lake fault, the Val Rita block is characterized by a maze of discontinuous, curvilinear reflections with general easterly dip down to 8 – 10 s, below which west-dipping events are prominent. A north–south cross profile reveals a highly reflective crust with dominantly horizontal reflection geometry below the Saganash Lake metavolcanic belt, and a steep truncation of reflection zones down to at least 7 s, which correlates with the surface trace of the Nansen Creek fault. This fault resembles well-known strike-slip faults in intraplate settings. The Saganash Lake fault, variably interpreted as a west-side-down normal fault with up to 15 km of throw or a major strike-slip zone, may be visible as a west-dipping, weakly reflective zone steeply truncating east-dipping reflections and becoming listric at depth. This interpretation accords with surface geological observations and gravity models for the structural geometry of the region in which the Groundhog River block is a thin thrust sheet of granulite perched on Abitibi belt rocks and truncated on the west by the crustal-scale Saganash Lake fault. Alternatively, the fault could be a seismically unresolved major transcurrent structure juxtaposing blocks with disparate reflection patterns in the upper 8 s. Limited amounts of late strike-slip motion have been inferred from various geophysical studies.

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Main active structures in the Barbados accretionary wedge of the Lesser Antilles Subduction: implications for slip partitioning

10.5194/egusphere-egu2020-10732 ◽

2020 ◽

Author(s):

Gaëlle Bénâtre ◽

Nathalie Feuillet ◽

Hélène Carton ◽

Eric Jacques ◽

Thibaud Pichot

Keyword(s):

Seismic Reflection ◽

Linear Structure ◽

Strike Slip ◽

Lesser Antilles ◽

Accretionary Wedge ◽

Seismic Reflection Data ◽

Megathrust Earthquakes ◽

Reflection Data ◽

Slip Partitioning ◽

Seismic Reflection Profiles

At the Lesser Antilles Subduction Zone (LASZ), the American plates subduct under the Caribbean plate at a slow rate of ~2 cm/yr. No major subduction megathrust earthquakes have occurred in the area since the 1839 and 1843 historical events, and the LASZ is typically considered weakly coupled. At the front of the LASZ, the Barbados accretionary wedge (BAW) is one of the largest accretionary wedges in the world. The width of the BAW decreases northward, owing to the increasing distance to the sediment source (Orinoco river) and the presence of several aseismic oceanic ridges, in particular the Tiburon ridge, that stops sediment progression. Marine geophysical studies conducted to date over the northern part of the BAW (Guadeloupe-Martinique sector) have mostly focused on resolving the geometry of the backstop. However, the structure of the wedge and the mechanical behavior of the subduction interface remain poorly known. Our study aims to describe the geometry of the BAW by a detailed morpho-tectonic analysis in order to place constraints on present and past dynamic interactions between the subducting and overriding plates.New high-resolution bathymetric data (gridded at 50 meters), CHIRP data and 48-channels seismic reflection profiles were acquired over the BAW in the Guadeloupe-Martinique sector during the CASEIS cruise (10.17600/16001800) conducted in 2016 with the IFREMER vessel N/O Pourquoi Pas? We present results from the analysis of these new data, complemented by existing bathymetry and seismic reflection data acquired by several previous cruises, with an emphasis on the inner wedge domain. The data reveal a 180 km-long linear structure between 15&#176;15&#8217;N and 16&#176;45&#8217;N latitude, imaged as a positive flower structure on several CASEIS seismic reflection profiles. We interpret this structure as a strike-slip fault and name it the Seraphine fault. The identification of a horse-tail structure linked to an eastward bend of the fault trace at its northern end, as well as left-stepping en &#233;chelon folds west of the Seraphine fault, allow to determine the kinematics of the fault as left-lateral strike-slip. The Seraphine fault could root at the toe of the backstop (at least in its central portion). CHIRP data show evidence of folding of recent sedimentary units that are linked to the Seraphine fault, supporting the idea of recent activity. While at odds with the low obliquity of the convergence in this area, the Seraphine fault could be the expression of slip partitioning, similarly to the Bunce fault observed father north along the LASZ where obliquity is much stronger.

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Architecture and Neogene kinematic of the Seagap fault, offshore Tanzania, West Somali Basin

10.5194/egusphere-egu21-8991 ◽

2021 ◽

Author(s):

David Iacopini ◽

Stefano Tavani ◽

Sara Pentagallo ◽

Cynthia Ebinger ◽

Marina Dottore Stagna ◽

...

Keyword(s):

Fracture Zone ◽

Regional Scale ◽

Strike Slip ◽

Strike Slip Fault ◽

Normal Displacement ◽

3D Seismic ◽

Seismic Reflection Data ◽

Reflection Data ◽

Oceanic Spreading ◽

Oriented Parallel

In the West Somali Basin, the classic plate tectonic reconstructions describe an early Cretaceous intraplate deformation of oceanic crust (Hauterivian to Aptian) followed by the activation of a major transform fault (Davie Fracture Zone) displacing Madagascar southward for more than 1000 km. In this contribution, using vintage and new high-resolution 2D, 3D seismic reflection data and exploration wells, we show the first clear images of a poorly known tectonic structure: the Seagap fault. The Seagap fault is represented by a complex fault zone of several hundred kilometres of extent, oriented parallel to the Davie Fracture Zone and defined by segment faults, relay zones and step overs structures. It appears to have continuously acted as left-lateral strike slip fault during the Paleogene and most of the Neogene. From structural and stratigraphic observations of both existing and newly interpreted 3D seismic data, the Seagap appears nucleating as a strike-slip fault by reactivating failed Jurassic oceanic spreading zones. At regional scale the main fault appears to cut the main Neogene pervasive extensional oblique rift structures and at place to re-work some of the major Cenozoic inherited structure, creating apparent restraining bend structure. The sinistral kinematic nature of the transcurrent history, suggests that the Seagap fault acted as an independent feature respect to the Davie Fracture Zone. During the Quaternary the Seagap, which also parallels the seismically active Kerimbas rift, shows reduced offsets and appears to slip with normal displacement. We discuss the tectonic significance of the Seagap fault with respect to both to the major extensional oblique rift structural trend offshore Tanzania and the Davie Fracture Zone.

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The near-surface geology of St. Georges Bay, Nova Scotia: implications for the Hollow Fault

Canadian Journal of Earth Sciences ◽

10.1139/e95-051 ◽

1995 ◽

Vol 32 (5) ◽

pp. 603-613 ◽

Cited By ~ 8

Author(s):

P. Durling ◽

K. Howells ◽

P. Harvey

Keyword(s):

Nova Scotia ◽

Seismic Reflection ◽

Deformation Zone ◽

Strike Slip ◽

Seismic Reflection Data ◽

Near Surface ◽

Cape Breton Island ◽

Deep Seismic Reflection ◽

Reflection Data ◽

Cape Breton

A formline contour map, which depicts the near-surface, structural configuation of the strata underlying St. Georges Bay, northeastern Nova Scotia, was made from bedding attitude data compiled in the coastal areas; apparent dips measured from single-channel seismic reflection data; and true strikes and dips calculated at survey track intersections. The geology interpreted from the formline map is characterized by northeast-striking faults and fold axes. The folds in the bay comprise broad, open synclines and narrow, tightly folded or faulted anticlines. Gravity and deep seismic reflection data suggest that the faulted anticlines are intruded by salt. Correlations from offshore to onshore suggest that the structures mapped offshore in the bay extend onshore. The onshore extensions of the faulted anticlines are mapped as faults, and their antiformal nature is subdued. They are locally associated onshore with Carboniferous Windsor Group outcrop. The offshore extension of the Hollow Fault, which is interpreted as a major northeast-striking, Carboniferous strike-slip fault, was mapped as a 1500–2500 m wide deformation zone, using deep seismic reflection data. Gravity lows coincident with the deformation zone are interpreted as being caused by salt intrusions. The trend of the Hollow Fault Zone suggests that this fault complex (and its associated strike-slip movement) continues on land near Mabou, Cape Breton Island. However, it does not appear to continue offshore along the northwest coast of Cape Breton Island, as previously suggested.

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