Paleomagnetism of DSDP Leg 55 basalts and implications for the tectonics of the Pacific Plate

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doi: 10.2973/dsdp.proc.55.135.1980
Author(s): Kono, Masaru
Author Affiliation(s): Primary:
Univ. Tokyo, Geophys. Inst., Tokyo, Japan
Volume Title: Initial reports of the Deep Sea Drilling Project covering Leg 55 of the cruises of the drilling vessel Glomar Challenger, Honolulu, Hawaii to Yokohama, Japan; July-September 1977
Volume Author(s): Shambach, James, editor; Jackson, Everett Dale; Koizumi, Itaru; Avdeiko, Gennady; Butt, Arif; Clague, David; Dalrymple, G. Brent; Greene, H. Gary; Karpoff, Anne Marie; Kirkpatrick, R. James; Kono, Masaru; Hsin Yi Ling; McKenzie, Judith; Morgan, Jason; Takayama, Toshiaki
Source: Initial reports of the Deep Sea Drilling Project covering Leg 55 of the cruises of the drilling vessel Glomar Challenger, Honolulu, Hawaii to Yokohama, Japan; July-September 1977, James Shambach, Everett Dale Jackson, Itaru Koizumi, Gennady Avdeiko, Arif Butt, David Clague, G. Brent Dalrymple, H. Gary Greene, Anne Marie Karpoff, R. James Kirkpatrick, Masaru Kono, Hsin Yi Ling, Judith McKenzie, Jason Morgan and Toshiaki Takayama. Initial Reports of the Deep Sea Drilling Project, Vol.55, p.737-752. Publisher: Texas A & M University, Ocean Drilling Program, College Station, TX, United States. ISSN: 0080-8334 CODEN: IDSDA6
Note: In English. 22 refs.; illus. incl. tables
Summary: (1) The paleolatitude of Suiko Seamount is 27° (N) with an uncertainty of 3.5° 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 106 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°. 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° and 14.6°, respectively, at the latitude of 27°. 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 ± 0.6 m.y., Dalrymple et al., 1977) and Meiji (69-72 m.y.) may represent insufficient sampling of PSV.
Year of Publication: 1980
Research Program: DSDP Deep Sea Drilling Project
IPOD International Phase of Ocean Drilling
Key Words: 18 Geophysics, Solid-Earth; Basalts; Cenozoic; Crust; Deep Sea Drilling Project; Demagnetization; East Pacific Ocean Islands; Emperor Seamounts; Equations; Hawaii; Hot spots; IPOD; Igneous rocks; Inclination; Leg 55; Magnetization; Natural remanent magnetization; North Pacific; Northwest Pacific; Oceania; Pacific Ocean; Paleolatitude; Paleomagnetism; Polynesia; Remanent magnetization; Sea-floor spreading; Site 430; Site 432; Site 433; Tectonophysics; United States; Volcanic rocks; West Pacific
Coordinates: N350000 N500000 E1750000 E1600000
Record ID: 1981027029
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from U. S. Geological Survey, Hawaiian Volcano Observatory, United States