Paleomagnetic investigations of Leg 144 volcanic rocks: paleolatitudes of the northwestern Pacific guyots

Nakanishi, M, Gee JS.  1995.  Paleomagnetic investigations of Leg 144 volcanic rocks: paleolatitudes of the northwestern Pacific guyots. Proceedings of the Ocean Drilling Program Scientific Results. 144:585-604.


Paleomagnetic properties of 340 minicore samples from 5 guyots in the northwestern Pacific Ocean were measured on board the JOIDES Resolution and in the paleomagnetic laboratories of the Ocean Research Institute, University of Tokyo, and of Lamont-Doherty Earth Observatory. Stepwise thermal and alternating-field (AF) demagnetizations typically isolate the same characteristic magnetization direction. The shipboard and shore-based paleomagnetic measurements suggest a paleolatitude of ~10°S for Limalok, Wodejebato, MIT, and Takuyo-Daisan guyots. Lo-En Guyot apparently was constructed at a latitude of 31°S. According to the radiometric age of volcanic rocks from MIT Guyot, the reversed polarity of the volcanic basement of MIT Guyot corresponds to Chron M1 or older. A reversed polarity remanence of Wodejebato Guyot was acquired during Chron C33R because radiometric age determinations for Wodejebato Guyot range from 79 to 85 Ma. Our paleolatitude estimates for Lo-En, MIT, and Takuyo-Daisan guyots differ from those derived from previous seamount magnetic anomaly modeling. The sense and magnitudeof this paleolatitude discrepancy are consistent with a significant contribution from viscous and induced magnetizations. We estimated the paleolatitudes of the guyots from the age data and from a previously published absolute-motion model for the Pacific Plate. Differences between these paleolatitude estimates and those derived from paleomagnetic measurements except for Wodejebato Guyot are smaller than 6°.