The Hatton Basin and continental margin: Crustal structure from wide‐angle seismic and gravity data

Vogt, U.; Makris, J.; O’Reilly, B. M.; Hauser, F.; Readman, P. W.; Jacob, A. W. B.; Shannon, P. M.

doi:10.1029/98jb00604

Cited by 59 publications

(66 citation statements)

References 32 publications

(10 reference statements)

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“…This is well supported by our data and might be explained by a rather thick crust already at that time (no isostatic equilibrium). A similar sedimentary structure as resolved by our data was identified by Vogt et al (1998) who analyzed seismic data obtained in the Rockall region across the Hatton Continental Margin. There, a strong velocity contrast within the sediments suggests an erosional unconformity surface between syn-rift and post-rift layers that was interpreted to have developed due to regional uplift driven by up welling of hot asthenosphere before anomaly 24 (early Eocene) time.…”

Section: U N C O R R E C T E D P R O O Fsupporting

confidence: 53%

“…Taking into consideration the range of v p in the uppermost mantle allowed by our data we relate the sub-crustal structure to represent anomalously hot uppermost mantle rather than an underplated body typical for rifted volcanic margins as observed e.g. in the outer Rockall region where Vogt et al (1998) identified an underplated body of 10 km thickness with a lateral extension of about 80 km. Interestingly, the crustal structure observed near this underplated body towards the continental crust of the Caledonides is very similar in thickness and velocity structure to that of our model.…”

Section: Discussionmentioning

confidence: 99%

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Crustal structure of the southeastern Iceland-Faeroe Ridge (IFR) from wide aperture seismic data

Bohnhoff¹,

Makris²

2004

Journal of Geodynamics

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The aseismic Iceland-Faeroe-Ridge (IFR) is of central importance in reconstructing the opening of the North Atlantic Ocean. To investigate the crustal structure of the IFR at its southeastern part we conducted a wide aperture seismic survey across the IFR from the Iceland Basin to the Norway Basin. Seismic energy was generated by two 60-litre sleeve guns and recorded by 42 ocean-bottom seismometers (OBS). Kinematic and dynamic forward modeling by two-point ray tracing was applied to develop a 2D velocity-depth model. The accuracy of the model obtained is better than 5% for both velocity and depth of interfaces. We find a Moho depth of 23 km below the crest of the ridge that decreases to about 15 km at either end of the line. The upper part of the crust exhibits P-wave velocities between 5.7 and 6.3 km/s that increase towards the Norway Basin. The lower crust is more homogeneous with v p ranging from 6.6 to 7.0 km/s. Upper and lower parts of the crust are separated by a first order discontinuity. Amplitudes (P m P) and arrival times (P n ) of wide-angle phases indicate upper-mantle velocities of 7.9 km/s. Furthermore we analyzed PS-converted phases for upper crustal depth levels and find a v p /v s ratio of 1.73 AE 0.04 equal to a Poisson's ratio of 0.25 with no significant lateral variations along the seismic line. On the crest of the ridge we identified a basalt layer embedded within the sedimentary sequence that was also penetrated by deep sea drilling and dated to 43AE 3.3 million years. Below the basalt layer we observed a low-velocity layer that is identified as Mesozoic sediment that was also observed to either end of the basalt. We conclude that the southeastern part of the IFR is composed of stretched continental crust and thus part of Paleo-Europe rather than oceanic crust formed by the Iceland hot spot. This conclusion is supported by the distribution of magnetic anomalies that allow identifying the passive continental margin approximately 100 km to the NW of our seismic line. #

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Section: U N C O R R E C T E D P R O O Fsupporting

confidence: 53%

Section: Discussionmentioning

confidence: 99%

Crustal structure of the southeastern Iceland-Faeroe Ridge (IFR) from wide aperture seismic data

Bohnhoff¹,

Makris²

2004

Journal of Geodynamics

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“…In this region, continental fragments are accreting and colliding with arcs and (2003), (6) Klingelhoefer et al (2007), (7) Funck (2003), (8) Gerlings et al (2011), (9) Fowler et al (1989), (10) Breivik et al (2012), (11) Lebedeva-Ivanova et al (2006), (12) Morewood et al (2005), (13) Vogt et al (1998), and (14) Collier et al (2009). other continental fragments. The North Palawan block is the best example of a passive margin fragment currently impinging on an island arc (the Philippine Mobile Belt).…”

Section: Continental Fragments and Microcontinents: Accreted Examplesmentioning

confidence: 99%

“…Bulk densities are also reported from studies where the authors combined gravity and seismic data to determine crustal density. References are (1) Funck et al (2008), (2) Grobys et al (2007), (3) Cooper et al (1981), (4) Grobys et al (2009), (5) Borissova et al (2003), (6) Klingelhoefer et al (2007), (7) Funck (2003), (8) Gerlings et al (2011), (9) Fowler et al (1989), (10) Breivik et al (2012), (11) Lebedeva-Ivanova et al (2006), (12) Morewood et al (2005), (13) Vogt et al (1998), and (14) Collier et al (2009 In the geological record, large volumes of crustal accretion are carried out by the collision of composite terranes or continental fragments onto continents (Vink et al, 1984). In North America, the amalgamation of the Wrangellia and Stikinia terranes resulted in a ribbon continent (SABIYA) that was ∼ 8000 km long and ∼ 500 km wide (Johnston, 2001).…”

Section: Composite Terranesmentioning

confidence: 99%

Future accreted terranes: a compilation of island arcs, oceanic plateaus, submarine ridges, seamounts, and continental fragments

Tetreault

Buiter

2014

Solid Earth

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Abstract. Allochthonous accreted terranes are exotic geologic units that originated from anomalous crustal regions on a subducting oceanic plate and were transferred to the overriding plate by accretionary processes during subduction. The geographical regions that eventually become accreted allochthonous terranes include island arcs, oceanic plateaus, submarine ridges, seamounts, continental fragments, and microcontinents. These future allochthonous terranes (FATs) contribute to continental crustal growth, subduction dynamics, and crustal recycling in the mantle. We present a review of modern FATs and their accreted counterparts based on available geological, seismic, and gravity studies and discuss their crustal structure, geological origin, and bulk crustal density. Island arcs have an average crustal thickness of 26 km, average bulk crustal density of 2.79 g cm −3 , and three distinct crustal units overlying a crust-mantle transition zone. Oceanic plateaus and submarine ridges have an average crustal thickness of 21 km and average bulk crustal density of 2.84 g cm −3 . Continental fragments presently on the ocean floor have an average crustal thickness of 25 km and bulk crustal density of 2.81 g cm −3 . Accreted allochthonous terranes can be compared to these crustal compilations to better understand which units of crust are accreted or subducted. In general, most accreted terranes are thin crustal units sheared off of FATs and added onto the accretionary prism, with thicknesses on the order of hundreds of meters to a few kilometers. However, many island arcs, oceanic plateaus, and submarine ridges were sheared off in the subduction interface and underplated onto the overlying continent. Other times we find evidence of terrane-continent collision leaving behind accreted terranes 25-40 km thick. We posit that rheologically weak crustal layers or shear zones that were formed when the FATs were produced can be activated as detachments during subduction, allowing parts of the FAT crust to accrete and others to subduct. In many modern FATs on the ocean floor, a sub-crustal layer of high seismic velocities, interpreted as ultramafic material, could serve as a detachment or delaminate during subduction.

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“…Funck et al (2008) identified an extension of the HVLC beneath the northern part of the Hatton Basin below crystalline crust about 10 km thick, and interpreted this to be due to magmatic additions to the crust rather than partial serpentinization of the upper mantle. Further south, a zone of HVLC has been detected beneath the Hatton continental margin, overlain by crust in which the lower layer has been completely attenuated (Vogt et al 1998;Shannon et al 1999). The HVLC can be traced southwards beneath the SDRs on Edoras Bank (Barton & White 1997).…”

Section: Hvlc Adjacent To the Ocean Marginmentioning

confidence: 90%

Controls on the location of compressional deformation on the NW European margin

Kimbell

Stewart

Gradmann

et al. 2016

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The distribution of Cenozoic compressional structures along the NW European margin has been compared with maps of the thickness of the crystalline crust derived from a compilation of seismic refraction interpretations and gravity modelling, and with the distribution of high-velocity lower crust and/or partially serpentinized upper mantle detected by seismic experiments. Only a subset of the mapped compressional structures coincide with areas susceptible to lithospheric weakening as a result of crustal hyperextension and partial serpentinization of the upper mantle. Notably, partially serpentinized upper mantle is well documented beneath the central part of the southern Rockall Basin, but compressional features are sparse in that area. Where compressional structures have formed but the upper mantle is not serpentinized, simple rheological modelling suggests an alternative weakening mechanism involving ductile lower crust and lithospheric decoupling. The presence of pre-existing weak zones (associated with the properties of the gouge and overpressure in fault zones) and local stress magnitude and orientation are important contributing factors.Gold Open Access: This article is published under the terms of the CC-BY 3.0 license.

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The Hatton Basin and continental margin: Crustal structure from wide‐angle seismic and gravity data

Cited by 59 publications

References 32 publications

Crustal structure of the southeastern Iceland-Faeroe Ridge (IFR) from wide aperture seismic data

Crustal structure of the southeastern Iceland-Faeroe Ridge (IFR) from wide aperture seismic data

Future accreted terranes: a compilation of island arcs, oceanic plateaus, submarine ridges, seamounts, and continental fragments

Controls on the location of compressional deformation on the NW European margin

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