95 = 5.8°) using the method of McFadden and Reid (1982).
A total of 48 intervals were studied from 36 sites along Transect EG65 to determine the magnetic polarity and whether some of the cored basaltic clasts were direct samples of basement or just loose and rotated clasts.
A typical demagnetization result is shown on a Zijderveld diagram in Figure F16. After removal of small secondary components related to viscous and/or drill-induced magnetization, the direction of the characteristic magnetic remanence is defined using standard principal component analysis (Kirschvink, 1980). Note that the azimuth of the drill cores is unknown; therefore, only the characteristic inclination is meaningful. Table T4 lists the demagnetization results, including characteristic inclination, intensity of natural remnant magnetization, magnetic susceptibility, and Königsberger ratio. Also given is the interpreted polarity together with important notes that are offered as a first interpretation of the paleomagnetic results.
Two intervals did not yield a reliable estimate of the characteristic inclination because of scattered demagnetization results (Holes SEG41A and SEG79C). Five intervals yielded intermediate inclinations. One of these intervals is from a loose basalt clast in Unit S-1 from Hole SEG39A. Four other intervals from Holes SEG44A, SEG45A, SEG74E, and SEG76A cannot easily be interpreted but possibly may represent short excursion events (Table T4). For all other intervals, the polarity is always of a reversed nature with a mean characteristic inclination of –67.4° (N = 29, k = 24, 95 = 5.8°) using the method of McFadden and Reid (1982).
A total of seven units defined as cored clasts from Holes SEG23A, SEG42A, SEG55C, SEG74E, SEG75A, SEG76A, and SEG79C were examined. Of these only Unit C-1 from Hole SEG79C did not yield a polarity, whereas Units C-1 from Holes SEG74E and SEG76A indicate possible excursions similar to their neighboring holes and unequivocally sampled basement. Unit C-1 from Hole SEG55C gives a normal inclination, opposite in direction to all neighboring holes, and we surmise that this clast had been transposed in the core box. The remaining C-units gave inclinations consistent with the neighboring holes and suggest that these represent in situ basaltic basement as sampled in Holes SEG23A, SEG42A, and SEG75A.
