caa a22 4500 46321627X CHVBK 20180405153157.0 cr unu---uuuuu 170326e20070601xx s 000 0 eng 10.1007/s00367-007-0074-2 doi (NATIONALLICENCE)springer-10.1007/s00367-007-0074-2 Sea-floor features related to hydrocarbon seeps in deepwater carbonate-mud mounds of the Gulf of Cádiz: from mud flows to carbonate precipitates [Elektronische Daten] [R. León, L. Somoza, T. Medialdea, F. González, V. Díaz-del-Río, M. Fernández-Puga, A. Maestro, M. Mata] Underwater images taken from deepwater carbonate-mud mounds located along the continental margin of the Gulf of Cádiz (eastern Central Atlantic) have identified a great variety of hydrocarbon seep-related geomorphic features that exist on the sea floor. An extensive photographic survey was made along the Guadalquivir Diapiric Ridge, after detailed examination of the main mounds identified on previous swath bathymetry coverage, high-resolution seismic imagery, dredge and gravity core data. Recognised fluid-induced geomorphic features include seep precipitates, named here generically as hydrocarbon-derived authigenic carbonates (HDACs), mud-breccia flows and piping/rills, at scales ranging from metres to centimetres. Based on the viscosity, texture, morphology, and the nature of observed features, we have categorized the geomorphic seeps into the following types: mud-breccia flows and liquid seepages, which can be grouped as highly viscous and viscous mud-breccia flows, gassy mud-breccia flows, and small-scale piping/rills; HDACs types, including massive crusts, "honeycombed” carbonate crusts, nodular aggregated crusts, steeply dipping to vertical slabs, and pipe-like formations (chimneys). These widespread geomorphic features observed along the carbonate-mud mounds reveal alternate periods of (1) active mud-flow extrusion (mud-volcano formation), (2) reduced seepage activity, with the formation of extensive carbonate features by chemosynthetic organisms, and (3) formation of hardgrounds and colonisation by non-chemosynthetic organisms such as deepwater corals (e.g. Lophelia pertusa, Madrepora oculata). The formation of large amounts of HDACs is related to the microbially mediated oxidation of hydrocarbon fluids (biogenic and thermogenic) during periods of slower fluid venting. This has led to the hypothesis that these carbonate-mud mounds could be built up by alternating episodes of varying fluid-venting rates, with peaks that may have been triggered by tectonic events (e.g. high-seismicity periods) and slower rates controlled by climate/oceanographic factors (e.g. glacial to interglacial climatic transitions, increasing shallow subsurface hydrate formation, and sealing of sea-floor fluid venting). Springer-Verlag, 2007 León R. Marine Geology Division, Geological Survey of Spain (IGME), Rios Rosas 23, 28003, Madrid, Spain aut Somoza L. Marine Geology Division, Geological Survey of Spain (IGME), Rios Rosas 23, 28003, Madrid, Spain aut Medialdea T. Marine Geology Division, Geological Survey of Spain (IGME), Rios Rosas 23, 28003, Madrid, Spain aut González F. Marine Geology Division, Geological Survey of Spain (IGME), Rios Rosas 23, 28003, Madrid, Spain aut Díaz-del-Río V. Centro Oceanográfico de Málaga, Instituto Español de Oceanografía, 29640, Málaga, Spain aut Fernández-Puga M. Marine Geology Division, Geological Survey of Spain (IGME), Rios Rosas 23, 28003, Madrid, Spain aut Maestro A. Marine Geology Division, Geological Survey of Spain (IGME), Rios Rosas 23, 28003, Madrid, Spain aut Mata M. Facultad de Ciencias del Mar, Universidad de Cádiz, Puerto Real, 1510, Cádiz, Spain aut Geo-Marine Letters Springer-Verlag 27/2-4(2007-06-01), 237-247 0276-0460 27:2-4<237 2007 27 367 https://doi.org/10.1007/s00367-007-0074-2 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s00367-007-0074-2 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- León R. Marine Geology Division, Geological Survey of Spain (IGME), Rios Rosas 23, 28003, Madrid, Spain aut NATIONALLICENCE 700 1- Somoza L. Marine Geology Division, Geological Survey of Spain (IGME), Rios Rosas 23, 28003, Madrid, Spain aut NATIONALLICENCE 700 1- Medialdea T. Marine Geology Division, Geological Survey of Spain (IGME), Rios Rosas 23, 28003, Madrid, Spain aut NATIONALLICENCE 700 1- González F. Marine Geology Division, Geological Survey of Spain (IGME), Rios Rosas 23, 28003, Madrid, Spain aut NATIONALLICENCE 700 1- Díaz-del-Río V. Centro Oceanográfico de Málaga, Instituto Español de Oceanografía, 29640, Málaga, Spain aut NATIONALLICENCE 700 1- Fernández-Puga M. Marine Geology Division, Geological Survey of Spain (IGME), Rios Rosas 23, 28003, Madrid, Spain aut NATIONALLICENCE 700 1- Maestro A. Marine Geology Division, Geological Survey of Spain (IGME), Rios Rosas 23, 28003, Madrid, Spain aut NATIONALLICENCE 700 1- Mata M. Facultad de Ciencias del Mar, Universidad de Cádiz, Puerto Real, 1510, Cádiz, Spain aut NATIONALLICENCE 773 0- Geo-Marine Letters Springer-Verlag 27/2-4(2007-06-01), 237-247 0276-0460 27:2-4<237 2007 27 367 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer