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Detailed paleomagnetic studies have been made on 15 sediment cores selected along north-south lines in the eastern and western Gulf of Mexico. The piston cores were sampled at 20-cm intervals immediately upon extrusion and measurements of natural remanent magnetization (NRM) were made using a 5hZ spinner magnetometer. Excursions of the geomagnetic field are recorded at 2 levels in many cores. Extrapolation of the ZY boundary in the western Gulf indicates that the younger feature is between 13.5 and 17.5 × 103 years BP, and is consistent with the age determination of the Laschamp event. Dates are not available for the eastern Gulf cores, but the depth of the paleomagnetic feature correlates with the expected sedimentation rates. The older feature is less di tinct and further extrapolation of the ZY boundary places it between 20.0 and 24.0 × 103 years BP. This age is within the range of a geomagnetic feature that is not the Laschamp.
These results show that with extreme care, paleomagnetic measurements may be used as a stratigraphic tool in the Gulf of Mexico. Several points should be considered. First, because of the high sedimentation rates, the 2 young features described herein are the only ones expected in piston cores from this region. Second, direction scatter is quite pronounced in the upper 1/2 m and lower few centimeters of several cores. Correlations at these levels are difficult. Finally, as measurement of the geomagnetic features described lasted for only a short time and did not traverse a full 180°, dense sampling is recommended to assure their definition.
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