Displacement of the Moho by the Outer Isles thrust shown by seismic modelling

Peddy, Carolyn P.

doi:10.1038/312628a0

Cited by 27 publications

(10 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The Outer Hebrides fault zone (Outer Isles thrust) is approximately planar, and can be followed as a continuous reflector to within 5 km of the Moho, projecting roughly to a normal sense offset in the Moho. Brewer & Smythe (1984), and Peddy (1984) have suggested that it can be extrapolated to cut the Moho. Wernicke (1986), on the basis of gentle warping of the Moho reflections, suggests that both the Outer Hebrides and Minch faults extend through the lithosphere.…”

Section: N Scotlandmentioning

confidence: 99%

Extensional structures on the western UK continental shelf: a review of evidence from deep seismic profiling

Cheadle¹,

McGeary²,

Warner³

et al. 1987

View full text Add to dashboard Cite

BIRPS deep seismic refection data collected on the western United Kingdom continental shelf show the existence of a wide variety of sedimentary basins, most of which originated during Palaeozoic-Mesozoic crustal extension. Symmetrical interior-fracture basins are numerous, but more complex basins are also common and show the importance of fault reactivation and the influence of pre-existing structures on basin development. All of the major basement-penetrating faults are interpreted as having been reactivated. They do not visibly cut through the entire crust and into the upper mantle. The crystalline crust thins dramatically beneath the basins indicating local crustal extensions of up to 60%, although regional extension is less than 30%.The typical BIRPS profile shows a highly reflective lower crust sandwiched between an unreflective upper crust and upper mantle. This pattern of reflectivity appears to be characteristic of deep seismic data collected from within extended regions. The relatively small amount of extension which has affected this region suggests that the highly reflective lower crust is more likely to be due to lithological variation formed by mafic igneous intrusion and underplating during crustal extension than to-extensional ductile fabrics within the lower crust. =SWAT profiles 2 to 7 and 9. Stipple pattern marks the extent of the post-orogenic basins crossed by the profiles: CB =Colonsay basin; CBB = Cardigan Bay basin; CISB = Central Irish Sea basin; ECB = Eastern Channel basin; FCB = Firth of Clyde basin; IHB =Inner Hebrides basin; LIB = Loch Indaal basin; MB = Malin basin; McB = Minch basin; NCB = North Channel basin; NCSB = North Celtic Sea basin; NLB = North Lewis basin; OHB = Outer Hebrides basin; PeB = Peel basin; PB = Portpatrick basin; PBB = Plymouth Bay basin; RT =Rathlin Trough; SB = Solway basin; SCSB = South Celtic Sea basin; SGB =St George's Channel basin; SHB = Sea of Hebrides basin; ST = Stanton Trough; WAB =Western Approaches basin; WCB =Western Channel basin; WOB=Western Orkneys basin. CP=Carnsore Point. Major faults shown: BFS =Bala fault system;

show abstract

Section: N Scotlandmentioning

confidence: 99%

Extensional structures on the western UK continental shelf: a review of evidence from deep seismic profiling

Cheadle¹,

McGeary²,

Warner³

et al. 1987

View full text Add to dashboard Cite

show abstract

“…Modelling has been used by Blundell et al (1985) to suggest that the Outer Hebrides fault zone extends right through the crust and by Peddy (1984) to suggest that it displaces the Moho by about 0.5 seconds down to the east, that is, as a normal fault. There is still some controversy about this result.…”

Section: Selected Line Drawingsmentioning

confidence: 99%

Seismic reflections from the lower crust around Britain

Matthews¹

1986

View full text Add to dashboard Cite

Summary A cartoon is presented which represents a time-section typical of the first 3000 km of BIRPS profiling over the continental shelf north, west and south of Britain. It shows a Mesozoic sedimentary basin in the hanging wall of a low-angle normal fault zone. The dipping fault reflection merges with layering in the lower crust which appears as several strong but short ( c. 4 km) horizontal reflections between about 6 s two-way travel time and the base of the crust at about 10 s. The uppermost mantle is devoid of reflections except where dipping events extend from the layered lower crust towards the base of the section at 15 s two-way time. The cartoon is justified by reference to examples from profiles. Discussion states present hypotheses that are being tested. The layering in the lower crust is real and due to lenses of flat-lying foliation about 4 km across and tens of metres in thickness in which the seismic velocity has been reduced by the presence of fluids. Brine has been suggested to account for the electrical conductivity of the lower crust, and carbon dioxide may be associated with granulites. The geometry implies that the lower crust was ductile at the time of faulting, and that the foliation became horizontal during Mesozoic stretching of West Europe.

show abstract

“…1a). Seismic reflection profiles suggest that the Outer Hebrides Fault Zone dips consistently at c. 25°E to SE down into the lower crust, intersecting and possibly offsetting the Moho at c. 25 km depth (Smythe et al 1982;Peddy, 1984). Interpretations of offshore borehole and seismic reflection data suggest that the fault zone was active during Proterozoic, Carboniferous and Mesozoic extension (e.g.…”

Section: Introductionmentioning

confidence: 99%

The initiation and early tectonic significance of the Outer Hebrides Fault Zone, Scotland

Imber¹,

Strachan

Holdsworth³

et al. 2002

Geol. Mag.

View full text Add to dashboard Cite

. (2002) Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details.

show abstract

Displacement of the Moho by the Outer Isles thrust shown by seismic modelling

Cited by 27 publications

References 6 publications

Extensional structures on the western UK continental shelf: a review of evidence from deep seismic profiling

Extensional structures on the western UK continental shelf: a review of evidence from deep seismic profiling

Seismic reflections from the lower crust around Britain

The initiation and early tectonic significance of the Outer Hebrides Fault Zone, Scotland

Contact Info

Product

Resources

About