J. Rodero et al., Late Quaternary seismic facies of the Gulf of Cadiz Spanish margin: depositional processes influenced by sea-level change and tectonic controls, MARINE GEOL, 155(1-2), 1999, pp. 131-156
Seismic facies and Quaternary depositional systems of the Gulf of Cadiz hav
e been characterized by means of high-resolution seismic profiles (airguns,
Geopulse and ORE 3.5 kHz). A total of 11 Pleistocene and two Holocene sequ
ences separated by type-1 or type-2 discontinuities were identified. The ag
e of the depositional sequences was determined based on foraminifera ages f
rom boreholes and by correlation with seismic profiles of the slope areas w
ith uniform deposition and without significant discontinuities. These seism
ic units have been mapped throughout the margin, allowing to establish the
correlation with eustatic sea-level curves and global climatic trends. The
distribution and geometry of the units reveals that most of the sedimentary
record was developed during episodes of forced regression. Ten regressive
periods, corresponding to 5th-order cycles arranged into 4th-order, were di
stinguished. Absolute water depths for the development of coastal deposits
in each unit were calculated using depth from present-day sea-level, correc
ted for tectonic subsidence in the area. The model for the evolution of the
depositional system of the Gulf-of Cadiz continental margin highlights the
strong influence of tectonism in the development of depositional bodies, c
ontrolling the distribution of deposits generally produced during episodes
of sea-level fall. (C) 1999 Elsevier Science B.V. All rights reserved.