Meissl, Sandra et al. (2011): Magnetic fabrics in Quaternary sediments, Ursa Basin, northern Gulf of Mexico record transport processes, compaction and submarine slumping

Leg/Site/Hole:
IODP 308
IODP 308 U1322
Identifier:
2011-087848
georefid

10.1016/j.margeo.2011.05.007
doi

Creator:
Meissl, Sandra
IFM-GEOMAR, Kiel, Germany
author

Behrmann, Jan H.
University of Bremen, Germany
author

Franke, Christine
author

Identification:
Magnetic fabrics in Quaternary sediments, Ursa Basin, northern Gulf of Mexico record transport processes, compaction and submarine slumping
2011
Marine Geology
Elsevier, Amsterdam, Netherlands
286
1-4
51-64
The continental slope of the northern Gulf of Mexico seaward of the Mississippi Delta is characterized by very rapid Quaternary sedimentation. Thick sequences of underconsolidated muds and mudstones are present, which are severely overpressured. In the Ursa Basin, Site U1322 of the Integrated Ocean Drilling Program (IODP) provided an excellent coring record of interleaved fine-grained turbidites and hemipelagic sediments, in part severely affected by submarine slumping and sliding after deposition. Cores were continuously sampled and analyzed for anisotropy of magnetic susceptibility (AMS), to elucidate the effects of different transport mechanisms and degree of settling and consolidation on magnetic fabric properties. Generally AMS ellipticity increases with depth irrespective of transport mode, due to loss of porosity. Samples from slumped mass transport deposits (MTD), however, have higher AMS if compared to immediately overlying non-slumped material. MTD samples dominantly show triaxial magnetic fabrics whereas those found in non-slumped sediments are much more oblate. Long axes of the fabric ellipsoid reflect the direction of eastward to southward suspension transport in samples not overprinted by sliding or slumping. Short ellipsoid axes in non-slumped material are vertical, and thus parallel to the axis of maximum uniaxial shortening. In the MTD samples, many short ellipsoid axes are inclined, reflecting an overprint of the uniaxial shortening by bed-parallel shearing induced by the slumping. Shear and MTD transport direction deduced from the fabrics is top-to-SE, downslope along the morphological axis of Ursa Basin. Generally we show that magnetic fabrics of muds and mudstones are sensitive recorders of sedimentary and tectonic processes, and can be used to reconstruct essential parts of basin history. Abstract Copyright (2011) Elsevier, B.V.
English
Serial
Coverage:Geographic coordinates:
North:28.0600
West:-89.0200East: -89.0100
South:28.0600

Sedimentary petrology; anisotropy; Atlantic Ocean; boreholes; Cenozoic; compaction; continental margin sedimentation; continental slope; cores; Expedition 308; fabric; foliation; Gulf of Mexico; Integrated Ocean Drilling Program; IODP Site U1322; lithostratigraphy; magnetic fabric; magnetic properties; magnetic susceptibility; magnetostratigraphy; marine sediments; mass movements; North Atlantic; northern Gulf of Mexico; paleomagnetism; porosity; Quaternary; sedimentation; sediments; shear strength; slumping; Ursa Basin;

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