scholarly journals Seismic reflection data, northern Gulf of St. Lawrence, 1000km of low energy seismic reflection profiles

1971 ◽  
Author(s):  
Keyword(s):  
Seismic Reflection ◽  
Low Energy ◽  
Seismic Reflection Data ◽  
Reflection Data ◽  
Seismic Reflection Profiles

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.

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.

Crustal geometry of the Abitibi Subprovince, in light of three-dimensional seismic reflector orientations

1998 ◽  
Vol 35 (5) ◽  
pp. 569-582 ◽  
Author(s):  
G Bellefleur ◽  
A J Calvert ◽  
M C Chouteau
Keyword(s):  
Seismic Reflection ◽  
Three Dimensional ◽  
Seismic Reflection Data ◽  
Volcanic Arc ◽  
The North ◽  
Reflection Data ◽  
Abitibi Subprovince ◽  
Seismic Reflection Profiles ◽  
Lower Crustal ◽  
Seismic Reflector

We provide precise estimates of reflector orientations beneath the Archean Abitibi Subprovince, using two distinct approaches based on Lithoprobe seismic reflection data. In the first, we use the dip of reflections observed on intersecting profiles to establish the three-dimensional orientation of reflective structures. In the second, the strikes and dips of reflectors are estimated in the crooked parts of seismic reflection profiles by calculating a measure of coherency along the traveltime trajectories defined by a particular azimuth, dip, depth, and medium velocity. Mid-crustal reflectors define two areas with distinctive geometry: reflectors beneath the southern Abitibi belt are oppositely dipping, and convergent at depth, providing a V-shape aspect to the greenstone rocks; other reflectors beneath the northern Abitibi belt are, in general, subparallel, dipping at an average of 30° toward the north. These north-dipping reflectors are partly disrupted by a low-reflectivity zone, which is attributed to rocks of the Opatica Subprovince, located underneath the northern Abitibi belt. Lower-crustal reflectors have a similar, shallowly north-dipping orientation throughout the Abitibi Subprovince. The geometry of the reflectors recovered is consistent with the different tectonic histories proposed for the southern and northern Abitibi assemblages, until common deformation during a north-south shortening event. Attitudes recovered in the northern Abitibi belt are consistent with tectonic scenarios involving underthrusting of Abitibi middle and lower crustal terranes beneath the Opatica belt, whereas the oppositely dipping reflectors recovered in the middle crust beneath the southern Abitibi belt could be representative of a rifted volcanic arc environment.

scholarly journals Southern continuation of the Wakeham Group and Robe-Noire mafic suite (eastern Grenville Province) from hydrocarbon-targeted seismic reflection data on Anticosti Island, Quebec, Canada

2016 ◽  
Vol 53 (9) ◽  
pp. 875-882 ◽  
Author(s):  
Nicolas Pinet
Keyword(s):  
Seismic Reflection ◽  
Seismic Unit ◽  
Grenville Province ◽  
Seismic Reflection Data ◽  
North Shore ◽  
Reflection Data ◽  
Simple Geometry ◽  
Anticosti Island ◽  
Seismic Reflection Profiles

Hydrocarbon-targeted seismic reflection profiles acquired on eastern Anticosti Island (Quebec) image subparallel reflections with significant continuity below the Paleozoic St. Lawrence Platform. These intra-basement reflections define a seismic unit with a relatively simple geometry characterized by broad open folds, an array of subparallel markers, and east-northeast-dipping faults. The reflective seismic unit likely corresponds to the southern extension of the Mesoproterozoic Wakeham Group and Robe-Noire mafic sills that are exposed on the nearby north shore of the Gulf of St. Lawrence, in the eastern Grenville Province of Quebec.

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.

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

&lt;p&gt;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.&lt;/p&gt;&lt;p&gt;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&amp;#176;15&amp;#8217;N and 16&amp;#176;45&amp;#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 &lt;em&gt;en &amp;#233;chelon&lt;/em&gt; 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.&lt;/p&gt;

scholarly journals A regional Alpine graphite décollement level beneath the NW Pannonian Basin

2019 ◽  
Vol 149 (3) ◽  
pp. 279 ◽  
Author(s):  
Gábor Csaba Tari ◽  
Viktória Németh ◽  
Ferenc Horváth † ◽  
Viktor Wesztergom
Keyword(s):  
Seismic Reflection ◽  
Pannonian Basin ◽  
Eastern Alps ◽  
Conductivity Anomaly ◽  
Seismic Reflection Data ◽  
Reflection Seismic ◽  
Reflection Data ◽  
Seismic Reflection Profiles ◽  
Seismic Reflectors ◽  
First Time

The so-called Transdanubian Conductivity Anomaly (TCA) of the Hungarian part of the NW Pannonian Basin has been well known for more than five decades. The exceptionally low resistivity (i.e. 1–2 Ωm) zone has a very large areal extent (on the order a few thousand km2) and it is an entirely subsurface anomaly occurring at depth between circa 3–15 km, with no corresponding outcrops. Various geological explanations of this enigmatic crustal-scale geophysical anomaly range from invoking sub-horizontal Alpine nappe contacts to sub-vertical dikes with graphite and/or saline fluid content. Only one possible analogue outcrop area was considered for the high conductivity anomaly so far, namely the Drauzug/Gailtal area of the Eastern Alps in Austria, some 300 km to the West from the TCA area. Previous attempts to find correspondence between the TCA and prominent seismic reflectors seen on 2D seismic reflection profiles were based on data acquired by research institutions. This study systematically correlates, for the first time, the TCA with 2D industry seismic reflection data in the same area. Our new results show a very strong correlation between the subsurface extent and location of the TCA with various sub-horizontally oriented Cretaceous Alpine nappe surfaces. In addition, we draw on the latest structural correlation of the Alpine nappe stack of the Transdanubian Range with its proper tectonic counterpart in the Eastern Alps.At the southern edge of the Upper Austroalpine units in northern Styria, in the Veitsch Nappe of the Greywacke Zone, numerous graphite localities are known historically. These laterally extensive graphite units in NW Styria formed as the result of greenschist-grade metamorphism of a Carboniferous coal sequence during the Cretaceous. For the first time, we describe here one well penetration of possibly age-equivalent graphitic units in NW Hungary. Correlation of the magnetotelluric anomaly with the distinct reflection seismic signature suggests that the same Palaeozoic graphitebearing Upper Austroalpine units should be present at 3–15 km depth in our study area.Therefore we propose that the best explanation for the observed extent and geometry of the TCA is the presence of graphite in subhorizontal, tectonically thinned detachment surfaces at the base of the Upper Austroalpine nappe edifice of NW Hungary

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