Magnetics of Bowie Seamount

Using the oceanographic ship, the Endeavor; the University of British Columbia undertook a study of Bowie Seamount (53°18', 135°41') during the summer of 1968. Receiving a proton precession magnetometer for the cruise from PNL, a magnetic field survey was included in the study. The magnitude of the observed anomaly was about 850 gammas. The regional was determined by data taken in an airborne magnetic survey done in 1958 by the Dominion Observatory. Corresponding to the topography, the contour plot of the magnetic field showed a strong linear trend from the SW to the NE. In addition, despite fairly symmetrical bathymetry, the observed anomaly is decidedly unsymmetrical, implying a non-uniform intensity of magnetization. This seems to be confirmed by the use of a three dimensional, model - assuming uniform magnetization - developed by Manik Talwani. Using the least squares best fit intensity of magnetization, a large discrepancy was found between the model and the observed anomaly. In light of the fact that the earth's magnetic field has reversed directions many times in its history, the above discrepancy may well be due to the fact that the lava flows of the seamount span at least one time boundary separating a normal and a reversed magnetic period. This is given some credence in that an age determination was made on one sample yielding an age of about 100,000 years, a normal period in the earth's magnetic history. This together with the fact that the magnetic anomaly over most of the seamount is negative yields the above conclusion.Science, Faculty ofEarth, Ocean and Atmospheric Sciences, Department ofGraduat