Seismic crustal structure in the Gulf of Cadiz (SW Iberian Peninsula) |
| |
Authors: | González-Fernández A Córdoba D Matias LM Torné M |
| |
Institution: | (1) Departamento de Geología, División de Ciencias de la Tierra, CICESE, Carr. Tijuana-Ensenada km 107, 22830 Ensenada, B.C., Mexico;(2) Departamento de Geofísica, Universidad Complutense, 28040 Madrid, Spain;(3) Centro de Geofisica da Univ. Lisboa, Rua da Escola Politecnica 58, Lisboa, Portugal;(4) Departamento de Geofísica, Instituto de Ciencias de la Tierra `Jaume Almera', CSIC, 08028 Barcelona, Spain |
| |
Abstract: | The sedimentary structure in the Gulf of Cadiz has been extensively studied by oil exploration companies. However, up to now
little is known about its deep crustal structure. Moreover, the total thickness of the sedimentary layers remains unknown
in large areas. The purpose of this paper is the crustal-scale interpretation of deep seismic near-vertical reflection and
refraction/wide-angle reflection data obtained during the IAM (Iberian Atlantic Margins) project, carried out in 1993. Our
results indicate that a continental type crust is underlying the entire Gulf of Cadiz, with progressive thinning from east
to west. The sedimentary cover shows a great thickness, reaching 8 km in the center of the Gulf. Three main sedimentary units
can be recognized: Jurassic-Cretaceous calcareous rocks, continuation of Algarve outcrops; the Allochthonous Units of Guadalquivir/Gulf
of Cadiz, the offshore continuation of the inland Carmona nappe; and sub-horizontal post-Miocene marine sediments. The crystalline
crust is divided into three main layers: the upper crust is characterized by P-wave velocity values of 5.7–6.1 km/s; the middle
crust shows values of 6.3–6.4 km/s; the lower crust has a mean vertical velocity gradient of 0.02 km/s/km, with velocities
between 6.9 to 7.1 km/s. The total crustal thickness varies from 27 km for the eastern part of the studied area, to 20 km
for the westernmost part. The crustal thinning is more pronounced in a N-S direction than in an E-W direction. No major structures
related with a defined Iberia-Africa plate boundary could be found.
This revised version was published online in November 2006 with corrections to the Cover Date. |
| |
Keywords: | crustal structure Gulf of Cadiz Iberian Peninsula passive margins seismic profiles |
本文献已被 SpringerLink 等数据库收录! |
|