(1) The paleolatitude of Suiko Seamount is 27 degrees (N) with an uncertainty of 3.5 degrees at the 95 percent confidence level. Since the sampling of PSV is adequate and since the magnetic stability is very high in this lava sequence, this estimate can be taken at its face value. (2) The 400-meter basaltic section cored on top of Suiko Seamount seems, from magnetic data, to have accumulated in a period greater than 104 years but less than 1.5 x 10 (super 6) years. This estimate is consistent with the radiometric age data (Dalrymple et al., this volume). Some flow units seem to have erupted in quick succession, whereas time gaps appear between other flow units, suggesting that the volcanism was intermittent and episodic, just as in the volcanoes of the island of Hawaii. The time interval estimated above also suggests that a substantial part of a seamount may have formed within a relatively short time, within a polarity interval, say. This explains why some of the seamount magnetic anomalies can be interpreted using a simple model (uniform magnetization), and gives some support to the paleomagnetism of seamount magnetic anomalies (e.g., Harrison et al., 1975). (3) A good record of paleosecular variation in inclination about 65 m.y. ago was obtained. The Suiko data (Figure 6) contain some portions where almost continuous changes are recorded, 12 or more time gaps, and about 15 extreme (minimum and maximum) values. They cover a time span long enough to sample the entire range of secular variation but short enough so that we can neglect the disturbing effects of geomagnetic polarity transition or plate motions. A precision parameter of K = 26 was obtained from the distribution of VGL, which corresponds to a VGP dispersion (S) of 15.9 degrees . This dispersion is significantly larger than those of historical or Brunhes-age lavas on Hawaiian islands (Doell and Cox, 1971, 1972), but is similar to that of 14C-dated flows on the island of Hawaii (Coe et al., 1978). It is also consistent with PSV models C and D of Cox (1970), which predict VGP dispersions of 14.3 degrees and 14.6 degrees , respectively, at the latitude of 27 degrees . This suggests that the magnitude of PSV at the Hawaiian hot spot either is similar, through the period 0 to 70 m.y. ago, to the worldwide trend, if adequate sampling is done (which is the conclusion of Coe et al., 1978), or has changed significantly between 65 and 1 m.y. ago. If the secular variation at the Hawaiian hot spot was indeed similar to the world average (at least for 25-70 m.y.), then the paleomagnetic data from Midway (27.7 + or - 0.6 m.y., Dalrymple et al., 1977) and Meiji (69-72 m.y.) may represent insufficient sampling of PSV.

West: 160.0000 East: 175.0000 North: 50.0000 South: 35.0000

Expedition: 55

Site: 55-430

Site: 55-432

Site: 55-433

Provider: SEDIS Publication Catalogue

Data set link: http://sedis.iodp.org/pub-catalogue/index.php?id=10.2973/dsdp.proc.55.135.1980 (c.f. for more detailed metadata)

Data download: application/pdf

This metadata in ISO19139 XML format