The University of Southampton
University of Southampton Institutional Repository

From continental extension to seafloor spreading: crustal structure of the Goban Spur rifted margin, southwest of the UK

Bullock, A.D. and Minshull, T.A. (2005) From continental extension to seafloor spreading: crustal structure of the Goban Spur rifted margin, southwest of the UK Geophysical Journal International, 163, (2), pp. 527-546. (doi:10.1111/j.1365-246X.2005.02726.x).

Record type: Article


We present a 169-km wide-angle velocity model across the Goban Spur rifted margin, southwest of the UK. A 120-km-wide intermediate region is identified between the first clear seafloor spreading magnetic anomaly (anomaly 34r) and thinned continental crust, where velocities increase from 4.5 km s1 to 6.8 km s1 in the top 4 km beneath acoustic basement. At depth it can be divided into a region where a 1.5-km-thick high-velocity layer (7.2–7.6 km s1) exists and a region where this layer is absent but velocities of 7 km s1 are present. Wide-angle PmP arrivals are observed across the whole of the intermediate region but a normal incidence reflection Moho is not present.
Based on these velocities and combined with seismic reflection, gravity and magnetic modelling along this transect we interpret the intermediate region to consist of a 70 km wide zone of exhumed mantle with high Poisson's ratio at top basement (>0.34), an extremely low topographic expression and a high-velocity deep layer. Empirical relationships between velocity and degree of serpentinization suggest that serpentinite content decreases with depth from 100 per cent at top basement to <25 per cent from 5–7 km into basement. The observed magnetic anomaly is best fit by a thin magnetized layer (1 km) of magnetization 2–3 A m1. The intense magnetization may be due to magnetite formation during a prolonged interaction of serpentinite with sea water. Between this exhumed mantle and anomaly 34r is a 50-km-wide region raised 400 m above the adjacent exhumed mantle, consisting of a series of basement ridges. Poisson's ratio is not well defined in this region, which may be composed of anomalous oceanic crust or exhumed mantle.

Full text not available from this repository.

More information

Published date: 2005
Keywords: extension, lithospheric deformation, melt, Poisson's ratio, ray tracing, refraction, seismology, rifted margin, S waves, seafloor spreading, serpentinite


Local EPrints ID: 18175
ISSN: 0956-540X
PURE UUID: 03d917c2-fb2d-4818-93b4-4d53abf6f4ab
ORCID for T.A. Minshull: ORCID iD

Catalogue record

Date deposited: 15 Nov 2005
Last modified: 17 Jul 2017 16:36

Export record



Author: A.D. Bullock
Author: T.A. Minshull ORCID iD

University divisions

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton:

ePrints Soton supports OAI 2.0 with a base URL of

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.