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

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

<p>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.</p><p>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°15’N and 16°45’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 <em>en échelon</em> 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.</p>

Seismic reflection profiles across the central Kapuskasing uplift

1994 ◽  
Vol 31 (7) ◽  
pp. 1016-1026 ◽  
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.

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

1992 ◽  
Vol 63 (3) ◽  
pp. 285-295 ◽  
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.

Seismic reflection, borehole and outcrop geometry of Late Wisconsin tills at a proposed landfill near Toronto, Ontario

1995 ◽  
Vol 32 (9) ◽  
pp. 1331-1349 ◽  
Author(s):  
Joseph I. Boyce ◽  
Nicholas Eyles ◽  
André Pugin
Keyword(s):  
Seismic Reflection ◽  
Seismic Reflection Data ◽  
Geophysical Logging ◽  
Greater Toronto Area ◽  
Reflection Data ◽  
Shallow Seismic ◽  
Surface Contaminants ◽  
Sand And Gravel ◽  
Seismic Reflection Profiles ◽  
High Degree

The search for new landfill sites in the Greater Toronto area of southern Ontario, Canada, is producing a wealth of data regarding the subsurface stratigraphy and geometry of Late Wisconsin (<25 ka) till deposits. Till strata are favoured as landfill substrates because of their wide surface extent, thickness (maximum ~60 m), high degree of overconsolidation, apparently massive character, and low permeability. However, problems are emerging where surface contaminants have migrated through till deposits into underlying aquifers along poorly understood transport paths. This paper reports the results of a detailed shallow seismic reflection investigation of a proposed 275 ha landfill site 40 km northeast of Toronto near Whitevale, where previous hydrochemical analysis and hydrogeological monitoring identified rapid vertical recharge of contaminated surface waters through Late Wisconsin tills up to 60 m thick. Seismic reflection data are ground truthed by drilling (36 holes; total drilled 3157 m), coring (1600 m), downhole geophysical logging, and outcrop data. The site stratigraphy at Whitevale consists of an uppermost Late Wisconsin till (Halton Till) separated from a lower till (informally named Northern till) by a silt, sand, and gravel complex. Seismic reflection profiles identify the presence of well-defined reflectors within the Northern till, which are correlated in outcrop with laterally extensive erosion surfaces overlain by sheet-like sands and gravels, up to 1 m thick, and boulder concentrations. Erosion surfaces and associated sediments record episodic scouring by subglacial meltwaters and provide potential "hydraulic windows" for the movement of surface contaminants through the till into underlying aquifers.

Integrating high‐resolution refraction data into near‐surface seismic reflection data processing and interpretation

Geophysics ◽  
1998 ◽  
Vol 63 (4) ◽  
pp. 1339-1347 ◽  
Author(s):  
Kate C. Miller ◽  
Steven H. Harder ◽  
Donald C. Adams ◽  
Terry O’Donnell
Keyword(s):  
Seismic Reflection ◽  
Velocity Model ◽  
Surface Velocity ◽  
Seismic Profiles ◽  
Seismic Reflection Data ◽  
Near Surface ◽  
Interval Velocity ◽  
Velocity Models ◽  
Reflection Data ◽  
Seismic Reflection Profiles

Shallow seismic reflection surveys commonly suffer from poor data quality in the upper 100 to 150 ms of the stacked seismic record because of shot‐associated noise, surface waves, and direct arrivals that obscure the reflected energy. Nevertheless, insight into lateral changes in shallow structure and stratigraphy can still be obtained from these data by using first‐arrival picks in a refraction analysis to derive a near‐surface velocity model. We have used turning‐ray tomography to model near‐surface velocities from seismic reflection profiles recorded in the Hueco Bolson of West Texas and southern New Mexico. The results of this analysis are interval‐velocity models for the upper 150 to 300 m of the seismic profiles which delineate geologic features that were not interpretable from the stacked records alone. In addition, the interval‐velocity models lead to improved time‐to‐depth conversion; when converted to stacking velocities, they may provide a better estimate of stacking velocities at early traveltimes than other methods.

scholarly journals Flexural strike-slip basins

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.

Shallow Deformation Along the Crittenden County Fault Zone Near the Southeastern Boundary of the Reelfoot Rift, Northeast Arkansas

1992 ◽  
Vol 63 (3) ◽  
pp. 263-275 ◽  
Author(s):  
E. A. Luzietti ◽  
L. R. Kanter ◽  
E. S. Schweig ◽  
K. M. Shedlock ◽  
R. B. VanArsdale
Keyword(s):  
Fault Zone ◽  
Seismic Reflection ◽  
Vertical Displacement ◽  
Surface Expression ◽  
Late Eocene ◽  
Seismic Reflection Data ◽  
Reflection Data ◽  
Structural Relief ◽  
Well Data ◽  
Seismic Reflection Profiles

Abstract The Crittenden County fault zone (CCFZ) is located near the southeast boundary of the Reelfoot rift in northeastern Arkansas. The southeastern boundary of the rift has been characterized as an 8-km-wide zone of down-to-the-northwest displacement. The CCFZ, however, shows significant down-to-the-southeast reverse faulting of Paleozoic and Cretaceous rocks and flexure and thinning within the Tertiary sedimentary section. We discuss four of nine Mini-Sosie seismic reflection profiles, each 1 to 2 km long, acquired over the surface projection of the CCFZ and Reelfoot rift boundary. One second of two-way traveltime data was recorded, which corresponds to a maximum depth of approximately 1.2 km. Sedimentary layers between 50 and 800 m are well imaged; deeper strata are evident but not well imaged. Well data at one site on the CCFZ indicate approximately 63 and 82 m of vertical displacement of Cretaceous and Paleozoic rocks, respectively. Proprietary seismic-reflection data show reverse displacement of these rock units, indicating compressional tectonics. From the Mini-Sosie profiles, we estimate structural relief across the CCFZ at the Paleocene (Fort Pillow Sand) level to range between 14 and 70 m. The overlying middle-to-late Eocene section shows a similar or slightly smaller amount of thinning, indicating that much of the movement on the CCFZ dates mid-to-late Eocene. Displacement, flexure, and thinning in the geologic section increases as the CCFZ converges with the Reelfoot rift boundary, in the southwest part of the area studied. Surface expression of the CCFZ has not been identified. Reflections from the Quaternary-Eocene unconformity, however, show warping, dip, or interruptions in places over the CCFZ, suggesting that the CCFZ may have experienced Quaternary or Holocene movement as well.

Quaternary Transgressive/Regressive Cycles in the Gulf of Argos, Greece

1990 ◽  
Vol 34 (3) ◽  
pp. 317-329 ◽  
Author(s):  
Tjeerd H. van Andel ◽  
Eberhard Zangger ◽  
Constantine Perissoratis
Keyword(s):  
High Resolution ◽  
Sea Level ◽  
Seismic Reflection ◽  
Stratigraphic Sequence ◽  
Seismic Reflection Data ◽  
Marine Deposits ◽  
Reflection Data ◽  
Marine Seismic ◽  
Seismic Reflection Profiles ◽  
Mediterranean Soil

AbstractBorings in the Argive Plain reveal cycles of marine incursions, each ending with a Mediterranean soil profile and followed by a prograded fluvial and coastal wedge. The sediment prism of the Gulf of Argos shelf, visible in high-resolution seismic reflection profiles, also consists of transgressive and regressive depositional sequences identified by onlap, downlap, and truncation of deposits. At least four major reflectors, recognizable by their high acoustic impedance and erosional features, can be correlated across the shelf. The sediments between each pair of reflectors represent the seaward part of a set of transgressive and regressive marine deposits. They can be matched to the stratigraphic sequence on land where each marine unit is topped by a soil. Corrected for subsidence, the terminations of the onlapping and downlapping units define a local sea-level history; its time scale can be derived from a comparison with the eustatic sea-level history deduced from ocean cores. Thus, marine seismic reflection data can be used for the correlation of Quaternary oceanic and terrestrial chronologies.

scholarly journals Stratigraphic and structural framework of the Neoproterozoic Paracuellos Group, Iberian Chains, NE Spain

2002 ◽  
Vol 173 (3) ◽  
pp. 219-227 ◽  
Author(s):  
J. Javier Álvaro ◽  
Marie-Madeleine Blanc-Valleron
Keyword(s):  
Seismic Reflection ◽  
Structural Complexity ◽  
Gradual Transition ◽  
Seismic Profiles ◽  
Seismic Reflection Data ◽  
Reflection Data ◽  
Sedimentary Evolution ◽  
Structural Framework ◽  
Bedded Chert ◽  
Seismic Reflection Profiles

Abstract The Neoproterozoic Paracuellos Group of the Iberian Chains constitutes the core of two disconnected faulted blocks, named the Paracuellos and Codos antiforms. Precise lithostratigraphic correlations between both areas are not possible due to the structural complexity and because marker beds do not persist laterally. This paper presents a crustal cross-section of the Neoproterozoic axial core (the Paracuellos antiform) based on surface geology, boreholes and seismic reflection profiles. Seismic reflection data reveal that the basement was directly involved by a major Hercynian structure, named here the Paracuellos fault, which splits longitudinally the Paracuellos axial core. In seismic profiles this fault occurs as a northeasterly-dipping reflector (60–70° steep), evidencing a bivergent geometry of the lateral crustal elements. The sedimentary evolution of the Neoproterozoic Iberian platform ranges from transgressive, non-cyclic, offshore to hemipelagic, black and green shales (Sestrica Formation) to progradational trends recording shoaling during episodes of rapid sediment influx (Saviñán Formation), presumably in response to a low standing sea-level. The siliciclastic succession is punctuated in the inner platform by deposition of phosphatic limestones (Codos Bed), representing a major shoaling event and demarcating a sharp regional change of sedimentation separating two similar siliciclastic tendencies. A diagenetically induced bedded chert (Frasno Bed) occurs in the outer platform, and is interpreted as being the product of at least two silicification episodes. Both the Codos and Frasno Beds are overlain by the Aluenda Formation, which exhibits nearshore to offshore features. An important sedimentary discontinuity appears across the Neoproterozoic-Cambrian transition. The Cambrian(?) Bámbola Formation is paraconformable with the Paracuellos Group displaying a gradual transition in inner platform areas, whereas an erosive unconformity occurs in outer areas. The horizon of the Neoproterozoic-Cambrian boundary is not identified in the Iberian Chains, where neither Cadomian deformation nor discordances are recognisable.

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