HR: 17:15h
AN: OS34B-06    [Abstracts]
TI: Interaction Between Methane Hydrates and mud Diapirs in the South Caribbean
AU: * Ojeda, G Y
EM: german.ojeda@ecopetrol.com.co
AF: Instituto Colombiano del PetrĒleo, km 7 Via Piedecuesta, Piedecuesta, 00000 Colombia
AU: Bernardo, L M
EM: luis.bernardo@ecopetrol.com.co
AF: Instituto Colombiano del PetrĒleo, km 7 Via Piedecuesta, Piedecuesta, 00000 Colombia
AU: LĒpez, C D
EM: cgeolopez@hotmail.com
AF: Universidad Industrial de Santander, Cra 27 Calle 9 Ciudad Universitaria, Bucaramanga, 00000 Colombia
AU: Olaya, I D
EM: iolaya@ecopetrol.com.co
AF: Instituto Colombiano del PetrĒleo, km 7 Via Piedecuesta, Piedecuesta, 00000 Colombia
AU: Hernandez, R
EM: roberto.hernandez@ecopetrol.com.co
AF: Empresa Colombiana de PetrĒleos, Calle 37 8-43, Bogota, 00000 Colombia
AB: The prominent reflector observed in marine seismic data from many continental margins known as `Bottom Simulating Reflector' (BSR) is known to coincide with the base of the methane hydrate stability zone. Because of the great significance of methane hydrates, BSRs have been the focus of many studies worldwide. Few studies, however, have investigated the nature and extent of the BSR in the south Caribbean. Seismic reflection data acquired off the Caribbean coast of Colombia display a prominent BSR beneath much of the seafloor of that area. This BSR has been observed between 13.5\deg N and 11.9\deg N, and between 72.5\deg W and 74.6\deg W, in water depths ranging between 1.6 and 4.1 km. The thickness of the methane hydrate layer represented by the BSR and the seafloor is consistent throughout the region, and is equivalent to some 550 to 600 ms of seismic two-way-time. The BSR is relatively continuous throughout the study area, except when disrupted by local faults and mud diapirs. Two end-members describe the interaction between BSRs and mud diapirs. On one end, the BSR is fully disrupted by the seismically transparent mud column. On the other end, the BSR is continuous across the mud column, and preserves the seismic amplitude as in the unintruded area. Some BSRs appear broken but maintain relicts embedded in the mud column. We hypothesize that the continuity of BSRs may provide an indication of the relative velocity of mud ascent. When the BSR is continuous across the mud column, it may indicate a relatively slow mud ascent, suggesting that the hydrate stability zone keeps pace with mud emplacement. On the other hand, BSRs disrupted by the mud column may indicate a relatively fast mud intrusion where the stability field cannot be restored upon being altered by the thermal and pressure disturbance from rising mud. Therefore, the presence and continuity of a BSR across mud diapirs in the south Caribbean may provide clues on the occurrence and pace of diapirism in the area.
DE: 9360 South America
DE: 8105 Continental margins and sedimentary basins
DE: 3015 Heat flow (benthic) and hydrothermal processes
DE: 3025 Marine seismics (0935)
DE: 1050 Marine geochemistry (4835, 4850)
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting