Sediments from Sites 1057 and 1061 of Ocean Drilling Program Leg 172 on the Blake Outer Ridge exhibit nearly isotropic magnetic susceptibility. Resolving the degree of anisotropy of magnetic susceptibility proved difficult in many samples because of the generally weak magnetic susceptibility of the sediments relative to the noise level of the susceptibility meters used. Lineation varies from 1.0 to 1.013 and foliation varies from 1.0 to 1.08 in the samples that pass rejection criteria. In general the foliation is better resolved than the lineation, particularly at Site 1061, where the foliation exhibits long-term trends that mimic the mean susceptibility. The changes in the foliation at this site are likely the result of changes in the magnetic mineralogy of the sediment. The poorly developed or absent magnetic fabric in the sediments overall can be attributed to high carbonate concentrations and to a circulation regime that was diffuse or with currents too weak to effectively align magnetic particles.
1Haskell, B., 2000. Data report: Anisotropy of magnetic susceptibility study of Quaternary sediments from the Blake and Blake-Bahama Outer Ridges, western North Atlantic. In Keigwin, L.D., Rio, D., Acton, G.D., and Arnold, E. (Eds.), Proc. ODP, Sci. Results, 172 [Online]. Available from World Wide Web: <http://www-odp.tamu.edu/publications/172_SR/chap_04/chap_04.htm>. [Cited YYYY-MM-DD]
2Limnological Research Center, University of Minnesota, 310 Pillsbury Drive SE, Minneapolis MN 55455, USA. haskell@tc.umn.edu
Initial
receipt: 23 August 1999
Acceptance: 24 March 2000
Web publication: 12 October 2000
Ms 172SR-211