Structural Characteristics of some Sedimentary Basins in Northern Baffin Bay

1973 ◽  
Vol 10 (8) ◽  
pp. 1267-1278 ◽  
Author(s):  
C. E. Keen ◽  
D. L. Barrett
Keyword(s):  
Seismic Reflection ◽  
Magnetic Measurements ◽  
Structural Characteristics ◽  
Gravity Data ◽  
Seismic Refraction ◽  
Sedimentary Basins ◽  
Structural Features ◽  
Ocean Basin ◽  
Normal Faults ◽  
Baffin Bay

Geophysical measurements along tracks crossing some of the main structural features of the northern Baffin Bay shelf are described. The data consist of seismic reflection, seismic refraction, gravity, and magnetic measurements. Results in four areas—Lancaster Sound, Melville Bay, Smith Sound and Jones Sound—are presented. Magnetic and gravity data are used to define the extent of sedimentary basins in these areas. Seismic reflection measurements delineate the structural characteristics of the upper 2 km of the sedimentary strata and allow comparisons between them to be made. Seismic refraction measurements show that the upper 2 km of sediment exhibit low velocities—less than 3.2 km/s. Little deformation of the sediments is observed in any of these areas, however, the strata in Lancaster Sound and in the Melville Bay graben appear to have experienced less faulting than those in Jones Sound and Smith Sound. Normal faults are characteristic of the latter two areas. Jones Sound is a structurally complex area and is filled by a lesser thickness of sediments than is found in the other basins. These sediments are terminated near the entrance to the sound by Precambrian basement. A deeper sedimentary basin occupies Smith Sound and trends across the Nares Strait lineament. Although the data are insufficient to allow a detailed structural analysis of the strata in these regions, we speculate that the differences in sedimentary structures can be related to the formation of the Baffin Bay ocean basin.

Seismic Reflection Expression of Reactivated Structures in the New Madrid Rift Complex

1988 ◽  
Vol 59 (4) ◽  
pp. 141-150 ◽  
Author(s):  
John. L. Sexton
Keyword(s):  
Seismic Reflection ◽  
Structural Features ◽  
Normal Faults ◽  
Earthquake Activity ◽  
Seismic Zone ◽  
Reflection Method ◽  
Intraplate Earthquakes ◽  
Reflection Data ◽  
Seismic Reflection Method ◽  
New Madrid

Abstract An important aspect of seismogenesis concerns the role of preexisting faults and other structural features as preferred zones of weakness in determining the pattern of strain accumulation and seismicity. Reactivation of zones of weakness by present day stress fields may be the cause of many intraplate earthquakes. To understand the relation between reactivated structures and seismicity, it is necessary to identify structures which are properly oriented with respect to the present-day stress field so that reactivation can occur. The seismic reflection method is very useful for identifying and delineating structures, particularly in areas where the structures are buried as in the New Madrid seismic zone. Application of the seismic reflection method in widely separated locations within the New Madrid rift complex has resulted in successful detection and delineation of reactivated rift-related structures which are believed to be associated with earthquake activity. The purpose of this paper is to discuss results from seismic reflection profiling in the New Madrid rift complex. Reflection data from several surveys including USGS Vibroseis* surveys in the Reelfoot rift area reveal reactivated faults and other deep rift-related structures which appear to be associated with seismicity. High-resolution explosive and Mini-Sosie** reflection surveys on Reelfoot scarp and through the town of Cottonwood Grove, Tennessee, clearly show reverse faults in Paleozoic and younger rocks which have been reactivated to offset younger rocks. A Vibroseis survey in the Wabash Valley area of the New Madrid rift complex provides direct evidence for a few hundred feet of post-Pennsylvanian age reactivation of large-offset normal faults in Precambrian-age basement rocks. Several earthquake epicenters have been located in the vicinity of these structures. In the Rough Creek graben, Vibroseis reflection data provide clear evidence for reactivation of basement faults. The success of these reflection surveys shows that well-planned seismic reflection surveys must be included in any program seeking to determine the relationship between preexisting zones of weakness and seismicity of an area.

scholarly journals Seismic reflection data reveal the 3D structure of the newly discovered Exmouth Dyke Swarm, offshore NW Australia

2020 ◽  
Author(s):  
Craig Magee ◽  
Christopher A.-L. Jackson
Keyword(s):  
Seismic Reflection ◽  
Surface Deformation ◽  
3D Structure ◽  
Sedimentary Basins ◽  
Dyke Swarm ◽  
Normal Faults ◽  
Seismic Reflection Data ◽  
Reflection Data ◽  
Dyke Swarms ◽  
Nw Australia

Abstract. Dyke swarms are common on Earth and other planetary bodies, comprising arrays of dykes that can extend for 10's to 1000's of kilometres. The vast extent of such dyke swarms, and their rapid emplacement, means they can significantly influence a variety of planetary processes, including continental break-up, crustal extension, resource accumulation, and volcanism. Determining the mechanisms driving dyke swarm emplacement is thus critical to a range of Earth Science disciplines. However, unravelling dyke swarm emplacement mechanics relies on constraining their 3D structure, which is extremely difficult given we typically cannot access their subsurface geometry at a sufficiently high enough resolution. Here we use high-quality seismic reflection data to identify and examine the 3D geometry of the newly discovered Exmouth Dyke Swarm, and associated structures (i.e. dyke-induced normal faults and pit craters), in unprecedented detail. The latest Jurassic dyke swarm is located on the Gascoyne Margin offshore NW Australia and contains numerous dykes that are > 170 km long, potentially > 500 km long. The mapped dykes are distributed radially across a 39° arc centred on the Cuvier Margin; we infer this focal area marks the source of the dyke swarm, which was likely a mantle plume. We demonstrate seismic reflection data provides unique opportunities to map and quantify dyke swarms in 3D in sedimentary basins, which can allow us to: (i) recognise dyke swarms across continental margins worldwide and incorporate them into models of basin evolution and fluid flow; (ii) test previous models and hypotheses concerning the 3D structure of dyke swarms; (iii) reveal how dyke-induced normal faults and pit craters relate to dyking; and (iv) unravel how dyking translates into surface deformation.

Geophysical studies on the eastern continental margin of Baffin Bay and in Lancaster Sound

1977 ◽  
Vol 14 (9) ◽  
pp. 1991-2001 ◽  
Author(s):  
H. R. Jackson ◽  
C. E. Keen ◽  
D. L. Barrett
Keyword(s):  
Structural Characteristics ◽  
Seismic Refraction ◽  
Continental Drift ◽  
Baffin Island ◽  
Seismic Reflection Data ◽  
Baffin Bay ◽  
Reflection Data ◽  
Basement High ◽  
Seismic Refraction Data ◽  
Sea Floor Spreading

The results of three crustal refraction lines on the western margin of Baffin Bay and one in Lancaster Sound are described. The refraction measurements in Baffin Bay along with earlier refraction, gravity, magnetic, and seismic reflection data are used to define the boundary between continental and oceanic crust. The results suggest that the transition from continental to oceanic material takes place in about 30 km. The seismic refraction data also suggest a sedimentary basin on the continental shelf with at least 6 km thickness of sediment which, however, thins rapidly near Baffin Island. This basin is truncated under the slope by either a basement high or carbonate rocks. Lancaster Sound is filled by about 10 km of sediments that could be either of Mesozoic or Paleozoic age based on comparisons with velocities in nearby wells. The sedimentary and structural characteristics of Lancaster Sound are discussed and related to the concepts of sea-floor spreading and continental drift.

Geophysical Studies in Baffin Bay and some Tectonic Implications

1972 ◽  
Vol 9 (3) ◽  
pp. 239-256 ◽  
Author(s):  
C. E. Keen ◽  
D. L. Barrett ◽  
K. S. Manchester ◽  
D. I. Ross
Keyword(s):  
Oceanic Crust ◽  
Seismic Reflection ◽  
Seismic Refraction ◽  
The Arctic ◽  
Spreading Center ◽  
Labrador Sea ◽  
Baffin Bay ◽  
Definitive Evidence ◽  
Nares Strait ◽  
The North

A recent seismic refraction experiment in the deep central region of Baffin Bay showed that it is underlain by oceanic crust. This paper describes the results of gravity, magnetic, and seismic reflection profiling measurements in the bay. There is no definitive evidence for a buried ridge or for magnetic lineations in the center of the area. The magnetic and gravity anomaly fields have been used to define the boundary between the oceanic and continental crust around the bay and therefore the extent of oceanic crust presumed to have been formed by sea-floor spreading. Some of the characteristics of the seismic reflection lines across the continental margins, perhaps typical of this area, are also discussed. The results have been used to reconstruct the history of opening of Baffin Bay in conjuction with geophysical measurements in the Labrador Sea to the south and over the Alpha Ridge in the Arctic Ocean to the north. An attempt has been made to reconcile the geometry of opening with continental geology. Two phases of spreading are suggested. The first involves openings, in both the Labrador Sea and in Baffin Bay, about a pole in the Canadian Arctic Islands. The second, most recent stage of opening, requires that the Nares Strait was once a transform fault, perhaps connecting a Baffin Bay spreading center to the Alpha Ridge to the north.

scholarly journals The Wishbone Ridge at the Chatham Rise Intersection: Structural Characteristics and Tectonic Implications

2021 ◽  
Author(s):  
◽  
Rachel Barrett
Keyword(s):  
New Zealand ◽  
Seismic Reflection ◽  
Structural Characteristics ◽  
Gravity Data ◽  
Large Igneous Province ◽  
Magnetic Data ◽  
The West ◽  
Satellite Gravity ◽  
Gondwana Margin ◽  
Seismic Reflection Profiles

<p>Geophysical data show that the West Wishbone Ridge, offshore of eastern New Zealand, is best described as having previously been a crustal transform fault, which first propagated along the eastern margin of the Hikurangi Plateau as subduction along the New Zealand sector of the Gondwana margin began to slow and reorientate between 105 and 101 Ma. Variation in the strike of the West Wishbone Ridge has resulted in contrasting compressional and extensional zones along the ridge. These regimes reflect the direction of strike offset from the direction of fault propagation, and constrain the sense of motion along the West Wishbone Ridge as having been dextral.  We find evidence that Cretaceous subduction along the Chatham Rise margin extended east of the margin offset at 174°W that marks the edge of Hikurangi Plateau subduction beneath the margin. Rotation of the Chatham Rise margin between 105 and 101 Ma was accommodated by westward broadening of the extensional zone of deformation associated with the West Wishbone Ridge near its intersection with the Chatham Rise. The amount of offset along the ridge indicates that significant transform motion along the West Wishbone Ridge south of ~40.5°S ceased ca. 101 Ma, coeval with the cessation of spreading of the Osbourn Trough, and of subduction of the Hikurangi Plateau.  Additionally, we find anomalously thick oceanic crust adjacent to the WWR and north of the Hikurangi Plateau (>12 km thick). This is attributed to the proximity of this crust to the Hikurangi Plateau Large Igneous Province.  The results of this study are based on seismic reflection and magnetic data recently collected during the 2016 R/V Sonne survey SO-246, as well as previously collected seismic reflection profiles and satellite gravity data.</p>

Three-dimensional geometries of relay zones in normal faults

2020 ◽  
Author(s):  
Giovanni Camanni ◽  
Vincent Roche ◽  
Conrad Childs ◽  
Tom Manzocchi ◽  
John Walsh ◽  
...  
Keyword(s):  
Seismic Reflection ◽  
Early Stage ◽  
Sedimentary Basins ◽  
Normal Faults ◽  
3D Seismic ◽  
Zone Structure ◽  
Cross Sectional ◽  
Mechanical Heterogeneity ◽  
Seismic Reflection Data ◽  
Fault Surface

&lt;p&gt;Individual normal faults are rarely single planar surfaces and often comprise arrays of fault segments arising from the earliest stages of fault propagation. Current models for the geometry and formation of relay zones between adjacent fault segments have been informed mainly by 2D analysis from either maps or cross-sections observed in outcrop and, to a lesser extent, by the analysis of relay zones from 3D seismic reflection data. Using high quality 3D seismic reflection datasets from a selection of sedimentary basins, we investigate fundamental characteristics of segmentation from the analysis of 67 normal faults with modest displacements (&lt; ca. 190 m) which preserve the 3D geometry of 532 relay zones. Our analysis shows that relay zones most often develop by bifurcation from a single fault surface but can also arise from the formation of segments which are disconnected in 3D. Relay zones generally occur between fault segments that step in either the dip or strike direction, and oblique relay zones with an intermediate orientation are less frequent. This is attributed to the influence of mechanical stratigraphy, and to a tendency for faults to locally propagate laterally and vertically rather than obliquely. Cross-sectional stepping of relay zones typically forms contractional rather than extensional relay zones, a configuration which is attributed to the development of early stage Riedel shears associated with fault localisation. Comparing datasets from different geological settings suggests that the mechanical heterogeneity of the faulted sequence and the influence of pre-existing structure are the underlying controls on the geometrical characteristics of relay zones in normal faults, and different combinations of these two controls can account for the variation in fault zone structure observed between datasets.&lt;/p&gt;

scholarly journals Neotectonic Activity in the Low-Strain Broken Foreland (Santa Bárbara System) of the North-Western Argentinean Andes (26°S)

Lithosphere ◽  
2020 ◽  
Vol 2020 (1) ◽  
pp. 1-25
Author(s):  
Ahmad Arnous ◽  
Martin Zeckra ◽  
Agostina Venerdini ◽  
Patricia Alvarado ◽  
Ramón Arrowsmith ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Seismic Reflection ◽  
Seismic Refraction ◽  
Sedimentary Basins ◽  
Santa Barbara ◽  
Seismic Reflection Data ◽  
Near Surface ◽  
South Central ◽  
Refraction Tomography ◽  
Fault Scarps

Abstract Uplift in the broken Andean foreland of the Argentine Santa Bárbara System (SBS) is associated with the contractional reactivation of basement anisotropies, similar to those reported from the thick-skinned Cretaceous-Eocene Laramide province of North America. Fault scarps, deformed Quaternary deposits and landforms, disrupted drainage patterns, and medium-sized earthquakes within the SBS suggest that movement along these structures may be a recurring phenomenon, with yet to be defined repeat intervals and rupture lengths. In contrast to the Subandes thrust belt farther north, where eastward-migrating deformation has generated a well-defined thrust front, the SBS records spatiotemporally disparate deformation along structures that are only known to the first order. We present herein the results of geomorphic desktop analyses, structural field observations, and 2D electrical resistivity tomography and seismic-refraction tomography surveys and an interpretation of seismic reflection profiles across suspected fault scarps in the sedimentary basins adjacent to the Candelaria Range (CR) basement uplift, in the south-central part of the SBS. Our analysis in the CR piedmont areas reveals consistency between the results of near-surface electrical resistivity and seismic-refraction tomography surveys, the locations of prominent fault scarps, and structural geometries at greater depth imaged by seismic reflection data. We suggest that this deformation is driven by deep-seated blind thrusting beneath the CR and associated regional warping, while shortening involving Mesozoic and Cenozoic sedimentary strata in the adjacent basins was accommodated by layer-parallel folding and flexural-slip faults that cut through Quaternary landforms and deposits at the surface.

scholarly journals The north-east Baffin Bay region, offshore Greenland – a new frontier petroleum exploration region

2008 ◽  
Vol 15 ◽  
pp. 65-68 ◽  
Author(s):  
Ulrik Gregersen
Keyword(s):  
Gravity Data ◽  
Sedimentary Basins ◽  
Hydrocarbon Exploration ◽  
Reservoir Rock ◽  
Petroleum Exploration ◽  
The Arctic ◽  
Structural Element ◽  
Baffin Bay ◽  
North East ◽  
The North

In recent years the Arctic has come into focus for hydrocarbon exploration, and areas offshore both West and East Greenland have been evaluated as promising frontier hydrocarbon provinces. Seven hydrocarbon exploration and ex ploitation licenses were awarded in 2007–2008 offshore the Disko–Nuussuaq region (Fig. 1), and two more have been awarded in the open-door region offshore south-western Greenland. In 2007, an extensive amount of new seismic and aeromagnetic data was acquired by the TGS-NOPEC Geop hysical Company in the north-eastern Baffin Bay region. Geophysical mapping has been initiated by the Geological Survey of Denmark and Greenland (GEUS) in the Melville Bugt region offshore North-West Greenland (Fig. 1) with the purpose of evaluating the hydrocarbon prospectivity. Initial interpretation of seismic and gravity data suggests the presence of deep sedimentary basins separated by structural highs. Geological information on source rock, reservoir rock and seal intervals from surrounding regions suggest that the Melville Bugt region is likely to have a significant petroleum potential. The study is based on public domain magnetic and gravity data, and all proprietary and public 2-D seismic data (Fig. 1) acquired before 2003. Seismic horizons from the ‘seismic basement’ to ‘base Quaternary’ are being interpreted regionally. Based on the seismic interpretation, a structural element map, depth-structure maps and isopach maps will be produced in order to assess the prospectivity of the Melville Bugt region.

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