Results 121 to 130 of about 182 (156)

Model of geomagnetic paleosecular variations for the Northern Hemisphere

Studia Geophysica et Geodaetica, 1991
A model of radial drifting and oscillating dipoles to represent geomagnetic palaeosecular variations, which showed to be appropriate for the Southern Hemisphere, is evaluated for the Northern Hemisphere. After a new fitting of some involved parameters, its theoretical results are compared with the palaeomagnetic data of Lake de Bouchet (France) and the
Ana M. Sinito, Juan F. Vilas
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Dipole/quadrupole family modeling of paleosecular variation

Journal of Geophysical Research: Solid Earth, 1988
Contrary to previous claims that the VGP scatter and its latitude variation deduced from the present field are atypical of those for the past 5 m.y., it is shown that it is in fact typical when correctly calculated. A simple and effective model for the paleosecular variation of lavas is developed by using this important observation together with the ...
P. L. McFadden, R. T. Merrill, M. W. McElhinny   +2 more
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Geomagnetic paleosecular variation in Easter Island, the southeast Pacific

Physics of the Earth and Planetary Interiors, 1998
Abstract We collected more than 250 samples from 45 sites in lava flows of the three volcanoes on Easter Island. The K–Ar whole rock dating was attempted on 13 sites. All of the ages obtained are younger than 0.8 Ma. Reliable paleomagnetic directions were obtained from 34 sites.
Masako Miki, Hiroo Inokuchi, Satoru Yamaguchi, Jun-ichi Matsuda, Keisuke Nagao, Nobuhiro Isezaki, Katsumi Yaskawa   +6 more
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A new method to determine paleosecular variation

Physics of the Earth and Planetary Interiors, 1994
Abstract This study is based on synthetic virtual geomagnetic pole distributions simulated by the sum of a Fisherian distribution characteristic of paleosecular variation (PSV) and a uniform distribution representing transitional data resulting from reversals and excursions of the geomagnetic field. Using such simulations, the optimum cutoff angle to
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On low-degree spherical harmonic models of paleosecular variation

Physics of the Earth and Planetary Interiors, 1996
Geomagnetic field directions over the past few millions of years have recently been compiled and these data bases can be used to build low-degree spherical harmonic models of the time-averaged field (TAF) and its paleosecular variation (PSV) variance structure.
Quidelleur, Xavier, Courtillot, Vincent
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Geomagnetic Paleosecular Variation During the Early Cretaceous

19th Congress of the Brazilian Geophysical Society - Proceedings
In this study, the amplitude of secular geomagnetic variation is investigated using directional paleomagnetic data obtained from rock samples collected in geological sections of the Paraná Basin.
Everton Frigo, ALANA BAIOCO, Carlos Augusto Sommer, Jairo Savian   +3 more
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Paleosecular variation during sequential geomagnetic reversals from Hawaii

Earth and Planetary Science Letters, 1999
Abstract Paleomagnetic directions measured from 175 flows in four volcanic sequences on the island of O'ahu (Hawaii) cover about 0.3 m.y. of geomagnetic field changes and include detailed records of the successive Gilbert-Gauss (3.57 Ma) and Lower Mammoth reversals (3.33 Ma).
Emilio Herrero-Bervera, Jean-Pierre Valet   +1 more
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Correcting distorted paleosecular variation in late glacial lacustrine clay

Physics of the Earth and Planetary Interiors, 2008
Abstract An undisturbed, horizontal chronostratigraphic marker horizon of laminated red glacio-lacustrine clay crops out over ∼25,000 km 2 in northern Ontario, Canada. The primary, clastic hematite laminae possess two stable vector components of magnetization. We sampled a 1.6 m vertical section at overlapping 2 cm intervals in cubic specimens (8 cm
G.J. Borradaile, B.S. Almqvist
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The Holocene paleosecular variation record from Elk Lake, Minnesota

Journal of Geophysical Research: Solid Earth, 1989
The paleosecular variation record of the geomagnetic field from Elk Lake, Minnesota, is presented and its implications are discussed. The Elk Lake record is compiled from measurements of four parallel cores with a 2 cm sampling interval (≈15 years).
Donald R. Sprowl, Subir K. Banerjee
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Paleosecular variation of the Honolulu Volcanic Series, Oahu, Hawaii

Journal of Geophysical Research, 1972
A paleomagnetic study of 193 sample cores drilled from 25 sites (lava flows) in the Honolulu volcanic series exposed on SE Oahu, Hawaii, yielded a mean angular standard deviation of 9.4°, with 95% confidence limits between about 7.7° and 11.9°. Thus, these lavas in the Brunhes normal polarity epoch confirm an earlier low value for paleosecular ...
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