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G-Cubed: Geochemistry, Geophysics, Geosystems; an electronic journal of the Earth sciences

 

Keywords

  • anisotropy of magnetic susceptibility
  • submarine landslides
  • slope failure
  • apparent overconsolidation

Index Terms

  • Geomagnetism and Paleomagnetism: Magnetic fabrics and anisotropy
  • Marine Geology and Geophysics: Continental shelf and slope processes
  • Marine Geology and Geophysics: Submarine landslides
Abstract
Cited By (1)
 

Abstract

Detecting compaction disequilibrium with anisotropy of magnetic susceptibility

Kurt Schwehr

Scripps Institution of Oceanography, La Jolla, California, 92093-0220, USA

Lisa Tauxe

Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California, 92093-0220, USA

Neal Driscoll

Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California, 92093-0220, USA

Homa Lee

U.S. Geological Survey, 345 Middlefield Road, Menlo Park, California, MS 937, 94025-3561, USA

In clay-rich sediment, microstructures and macrostructures influence how sediments deform when under stress. When lithology is fairly constant, anisotropy of magnetic susceptibility (AMS) can be a simple technique for measuring the relative consolidation state of sediment, which reflects the sediment burial history. AMS can reveal areas of high water content and apparent overconsolidation associated with unconformities where sediment overburden has been removed. Many other methods for testing consolidation and water content are destructive and invasive, whereas AMS provides a nondestructive means to focus on areas for additional geotechnical study. In zones where the magnetic minerals are undergoing diagenesis, AMS should not be used for detecting compaction state. By utilizing AMS in the Santa Barbara Basin, we were able to identify one clear unconformity and eight zones of high water content in three cores. With the addition of susceptibility, anhysteretic remanent magnetization, and isothermal remanent magnetization rock magnetic techniques, we excluded 3 out of 11 zones from being compaction disequilibria. The AMS signals for these three zones are the result of diagenesis, coring deformation, and burrows. In addition, using AMS eigenvectors, we are able to accurately show the direction of maximum compression for the accumulation zone of the Gaviota Slide.

Received 2 June 2006; accepted 29 August 2006; published 3 November 2006.

Citation: Schwehr, K., L. Tauxe, N. Driscoll, and H. Lee (2006), Detecting compaction disequilibrium with anisotropy of magnetic susceptibility, Geochem. Geophys. Geosyst., 7, Q11002, doi:10.1029/2006GC001378.

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