Tectonics and mud volcano development in the Gulf of Cádiz

Ferromanganese nodules and micro-hardgrounds associated with the Cadiz Contourite Channel (NE Atlantic): Palaeoenvironmental records of fluid venting and bottom currents

“…Similarly, burrowing structures (burrowing discontinuities) and relicts of sediment laminations (detritus-rich layers) are frequently observed within the nodules, in agreement with a subsurface origino Similar textures have been observed in carbonate chimneys and crusts in the area Merinero et al, 2008;Magalhaes et al, 2012). The host sediments should be rich in hydrocarbons related to the extended mud vulcanism and diapirism of the Gulf of Cadiz Medialdea et al, 2009). In these environments reducing conditions are common and favour carbonate nodule accretion a few centimetres below the sediment-water interface.…”

“…).ln addition, thermogenic hydrocarbons (n-alkanes and phenanthrene) were discovered in the samples analysed (Fig. 8c), in accordance with fluid venting from deep-seated reservoirs towards the sea-bottom through mud diapirs, mud volcanoes and fault systems (González et al, 2009;Medialdea et al, 2009). Hydrocarbons contained in the nodules were also detected in host sediments and carbonate chimneys and crusts in the area.…”

“…The development and evolution of this part of the Gulf of Cadiz margin has been controlled since the Late Messinian by the exchange of water masses through the Strait of Gibraltar, also affected by c1imatic cycles and tectonic events (e.g. Kenyon and Belderson, 1973;Llave et al, 2006;Voelker et al, 2006;Medialdea et al, 2009;León et al, 2010). We present a complete characterisation of these deposits based on a broad dataset that has led us to propose a genetic and evolutionary model Iinked to the mud volcanism-diapirism and palaeoceanographic evolution of the CCC, thus increasing knowledge about the interpretation of environmental changes.…”

The role of neo-tectonics in the sedimentary infilling and geomorphological evolution of the Guadalquivir estuary (Gulf of Cadiz, SW Spain) during the Holocene

“…The present geological structure of the Gulf of Cadiz is the result of the European-African plate convergence motion, dextral strike-slip along the Azores-Gibraltar Plate Boundary (Medialdea et al, 2009). This plate convergence lasted from Mid Oligocene up to Late Miocene times and then continued with slow Late…”

“…alignments, most of which are NE-SW and NW-SE oriented; these alignments nurture mud volcanoes and diapiric processes (Medialdea et al, 2009). …”