Michael McWilliams1, Robin T. Holcomb2, F. C. Champion3
1Geophysics Department, Stanford University, Stanford, California 94305, U. S. A.
2U. S. Geological Survey, Vancouver, Washington 98663, U. S. A.
3U.S. Geological Survey, Menlo Park, California 94025, U.S.A.
Tóm tắt
New palaeomagnetic data from 106 14C-dated lava flows ranging in age from 200 to 31000 years b.p. yield an estimated angular dispersion value of 9.5°. These data and other new geological information permit a more precise estimate of the time interval recorded by lava flow sequences previously used to measure palaeosecular variation in Hawaii. When weighted according to revised estimates of recording interval, the combined Brunhes lava sequences yield an angular dispersion of 11.21));j) degrees, still lower than that predicted by global models of the secular variation. Several of the lava flow sequences previously thought to have recorded quiet intervals of geomagnetic behaviour actually record only very short time intervals.
