RT Journal Article
T1 Vast fields of hydrocarbon-derived carbonate chimneys relatedto the accretionary wedge/olistostrome of the Gulf of Cádiz
A1 Díaz del Río, Víctor
A1 Somoza Losada, Luis
A1 Martínez Frías, Jesús
A1 Mata, M. Pilar
A1 Delgado Huertas, Antonio
A1 Hernández Molina, F.J.
A1 Lunar Hernández, Rosario
A1 Martín Rubí, Juan Antonio
A1 Maestro, Adolfo
A1 Fernández Puga, Mª Carmen
A1 León Buendía, Ricardo
A1 Llave, E.
A1 Medialdea, Teresa
A1 Vázquez, Juan Tomás
AB We report the first discovery and sampling of vast fields of hydrocarbon-derived carbonate chimneys along the Gulf of Ca¤diz continental slope, at depths between 500 and 1200 m. A large variety of carbonate chimneys (more than 200 samples) were recovered from four different areas, named the DIASOM, TASYO, GBF (Guadalquivir Basin) and ESF (East Moroccan) fields. Observations from an underwater camera revealed a spectacular high density of pipe-like chimneys, some of them longer than 2 m, lying over the sea floor, and some protruding from muddy sediment. Local fissures and alignment of isolated chimneys were also observed, suggesting that their distribution is controlled by fault planes. Chimneys collected show a wide range of morphological types (spiral, cylindrical, conical, mushroom-like and mounded) with numerous nodule protuberances and ramified fluid channelways. The chimneys are mainly composed of authigenic carbonates (ankerite, Fe-bearing dolomite and calcite) with abundance of iron oxides, forming agglomerates of pseudo-pyrite framboids. N18O isotopic values vary from 0.7 to 5.5x whereas N13C values indicate that chimney carbonates are moderately depleted in 13C, ranging from 346xto 320xPDB, interpreted as formed from a mixture of deep thermogenic hydrocarbons and shallow biogenic methane. These vast fields of carbonate chimneys imply new considerations on the importance of hydrocarbon fluid venting in the Gulf of Ca¤diz and, moreover, on the active role of the olistostrome/accretionary wedge of the Gibraltar arc.
PB Elsevier B.V.
SN 0025-3227
YR 2003
FD 2003
LK https://hdl.handle.net/20.500.14352/58165
UL https://hdl.handle.net/20.500.14352/58165
LA eng
NO Spanish Marine Science and Technology Program,
DS Docta Complutense
RD 18 may 2024