10.
Brunhes Chron Magnetic Field Excursions Recovered from Leg 172 Sediments1
Steve
P. Lund,2 Trevor Williams,3
Gary D. Acton,4 Brad Clement,5
and Makoto Okada6
ABSTRACT
During Ocean Drilling
Program Leg 172, we recovered long-core paleomagnetic records of 14
"plausible" magnetic field excursions within the Brunhes Chron at
Sites 1060-1063, separated by more than 1200 km. New U-channel
paleomagnetic studies of all 14 excursions indicate that 12 have true
excursional directions and are almost certainly "real" geomagnetic
field excursions, but five excursions still require discrete sample
paleomagnetic measurements to further replicate these results. U-channel
measurements for two of the original 14 "plausible" excursions (3
and 5)
did not show evidence of true excursional directions and are no longer
considered real. U-channel
measurements also identified one new excursion not identified during shipboard
measurements. We also identified other types of anomalous directional
variability that we currently think may be due to systematic biases in the
long-core and U-channel
measurement process. Further study using discrete samples will be necessary to
resolve such uncertainties. All of these observations suggest that excursions
are not rare, random perturbations of the stable geomagnetic field, but rather
an important systematic and distinct component of the Earth's magnetic field
variability between field reversals.
1Lund,
S.P., Williams, T., Acton, G.D., Clement, B., and Okada, M., 2001. Brunhes Chron
magnetic field excursions recovered from Leg 172 sediments. 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_10/chap_10.htm>.
[Cited YYYY-MM-DD]
2Department
of Earth Sciences, University of Southern California, University Park, Los
Angeles CA 90089, USA. slund@usc.edu
3Department
of Geology, University of Leicester, Leicester LE1 7RH, United Kingdom.
4Ocean
Drilling Program, Texas A&M University, 1000 Discovery Drive, College
Station TX 77845-9547, USA.
5Department
of Geology PC344, Florida International University, University Park, Miami FL
33199, USA.
6Department
of Environmental Sciences, Ibaraki University, Bunkyo 2-1-1, Mito 310, Japan.
Initial
receipt: 24 November 1999
Acceptance: 18 February 2001
Web publication: 6 June 2001
Ms 172SR-216
