Morphotectonics and strain partitioning at the Iberia-Africa plate boundary from multibeam and seismic reflection data

TLDR: In this article, a set of new multibeam bathymetry, multi-channel and single-channel seismic data was used to image the main morphological features of tectonic origin of a significant part of the Gulf of Cadiz from the continental shelf to the abyssal plain.

About: This article is published in Marine Geology.The article was published on 2009-12-15 and is currently open access. It has received 123 citations till now. The article focuses on the topics: Seismotectonics & Morphotectonics.

Figures

Fig. 12. Segment of multi-channel seismic line ARRIFANO 92-10 showing the deep 1194 origin of fluidized sediments breaching through the Mesozoic rift units and accretionary 1195 prism. Also note that the most recent unit is not involved in the thrust stacking tectonics 1196 of the accretionary wedge (see text for discussion, for location of line see Fig. 3). The 1197 steeply dipping north westernmost fault is the Aljezur fault bounding the deposits of the 1198 Sagres valley. Note that the chaotic body under the Sagres valley also has imbricated 1199 horizons but has no influence on the seafloor morphology (see text for discussion). 1200

Fig. 2. Seismicity of the study area, the main faults and boundaries of the Accretionary 1122 Wedge of the Gulf of Cadiz and Horseshoe Gravitational Unit as mapped in previous 1123 works (Sartori et al., 1994; Torelli et al., 1997; Gutscher et al., 2002; Gràcia et al., 2003; 1124 Terrinha et al., 2003; Iribarren et al., 2007). AF- Aljezur Fault; AWDF- Accretionary 1125 Wedge Deformation Front; GF- Gorringe Fault; HGU- Horseshoe Gravitational Unit; 1126 HsF- Horseshoe Fault; MPF- Marquês de Pombal Fault; PF- Portimão Fault; PSF- 1127 Pereira de Sousa Fault; QF- Quarteira Fault; Triangles show the location of mud-1128 volcanoes. 1129

Fig. 9. Multi-channel seismic line VOLTAIRE 3 and line drawing interpretation. The 1176 Guadalquivir basement high of Carboniferous age is bound by a NW-SE trending 1177 Mesozoic extensional fault, reactivated as a reverse fault (1st movement) that resumed 1178 its extensional movement in late Miocene through Present times (see text for discussion, 1179 for location of line see Fig. 1). The topographic bulge on top of the strike-slip fault is 1180 imaged in 3D in Fig. 6F. 1181

Fig. 1. Location and main morphological features of the study area. Inset shows the 1116 geotectonic location of the area and the relative motions of the Eurasia, Nubia and 1117 North America lithospheric plates in mm/year. Triangles show location of mud 1118 volcanoes. 1119

Fig. 11. Segment of multi-channel seismic profile IAM-3 at the contact between the 1188 Coral Patch Ridge (CPR) and the Horseshoe valley. Arrows point to folds in recent 1189 sediments on the seafloor as imaged on the MATESPRO bathymetry (see Figs. 3 and 1190 7). Note that these faults cut across seismic discontinuity D that outlines the 1191 decollement of the seismic chaotic facies. 1192

Fig. 7. Shaded relief image (perspective view) of the Giant Scours (GS), L1 and L2 1156 WNW-ESE trending lineaments (interpreted as strike slip faults, max. total length 1157 250km, see Fig. 11) and associated en echelon folds on sea floor recent sediments 1158 indicating dextral strike-slip movement component on the faults. Approximate depth 1159 4000m, confer with Figs. 1 and 4. Position of seismic lines in Figs. 11, 15 and 16 is also 1160 shown. Detail of the en echelon folds on L1 in the Horseshoe Abyssal Plain is shown in 1161 Fig. 6E. 1162