Fastsed

Fabric genesis, strength and physical properties of young Sediments, Ursa and Brazos-Trinity basins, Gulf of Mexico. A follow-up laboratory study of IODP Expedition 308.

Duration: 01.08.2006-30.06.2010

Financially supported by: DFG

How do catastrophic submarine mass movements come about, and are sediment consolidation, fabric genesis, and texture development important controlling factors? This is the principal question of the FastSed project. In an environment which has arguably the fastest fine-grained sedimentation on modern Earth, IODP Expedition 308, Gulf of Mexico Hydrogeology, has created a unique and comprehensive data set of sediment petrography, physical properties, and downhole measurements of overpressure. These data serve as foundation for a study of geotechnical properties, microfabric and crystallographic preferred orientation of clays to identify and quantify fabric building mechanisms in muds sedimented by fallout and by submarine mass transport. The analytical techniques employed are triaxial testing and ring shear testing. Reference materials are studied by scanning electron microscopy and X-ray texture goniometry, and are investigated for their magnetic (AMS) fabrics. FastSed results make a basic contribution to the assessment of stability problems of sedimented continental slopes. This is especially relevant for areas where current and future exploration for hydrocarbons require major technical installations at the seafloor, such as the Gulf of Mexico or the mid-Norwegian margin.

Working area

The drilling cores, which were taken and examinated during the IODP expedition 308 come from the Brazos-Trinity and Ursa Basins situated in the northern Gulf of México.

 

Cross section of the Ursa Basin

Interpreted reflection seismic cross-section, Ursa Basin. The sand-bearing Blue Unit is incised by a channel-levee complex and overlain by a thick and heavily slumped hemipelagic mudstone wedge that thickens to the west (=left). After Flemings et al. (2006)

Samples

Combination diagram showing lithology, porosity, peak shear strength from IODP sites U1324 (left) and U1322 (right). Red dots in lithological column indicate samples for triaxial testing, blue dots indicate samples for ring shear testing. Modified after Flemings et al. (2006)