Results 121 to 130 of about 181 (155)

Quantifying paleosecular variation: Insights from numerical dynamo simulations

Earth and Planetary Science Letters, 2013
Abstract Thanks to advances in dynamo modelling, it is now possible to produce numerical sequences of magnetic polarity reversals over periods of time equivalent to several tens of millions of years. Using a set of five numerical models integrated over the equivalent of 40–50 Myr, we generated synthetic data analogous to paleomagnetic data derived ...
Stuart Gilder, Florian Lhuillier
exaly   +2 more sources

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
openaire   +1 more source

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
openaire   +2 more sources

Assessing Paleosecular Variation Averaging and Correcting Paleomagnetic Inclination Shallowing

Journal of Geophysical Research: Solid Earth
AbstractThis paper addresses one of the critical questions of scientific inquiry: How do we know when a given data set is representative of the phenomenon being examined? For paleomagnetists, the question is often whether a particular data set sufficiently averaged paleosecular variation (PSV).
David Heslop, Stuart Gilder, Lisa Tauxe   +2 more
exaly   +3 more sources

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
openaire   +1 more source

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
openaire   +1 more source

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
openaire   +1 more source

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
openaire   +1 more source

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 ...
openaire   +1 more source

Archaeo‐ and paleosecular variation, and long‐term asymmetries of the geomagnetic field

Reviews of Geophysics, 1983
This report summarizes progress made during the last four years in (i) obtaining records of the geomagnetic secular variation using paleomagnetic techniques, (ii) analysis and modelling of the secular variation, and (iii) the study of asymmetries in the time‐averaged field: seen both as departures from the geocentric axial dipole model, and as ...
Charles E. Barton, Robert T. Merrill
openaire   +1 more source