Equatorial paleopoles and behavior of the dipole field during polarity transitions

Steinhauser, Peter; Vincenz, S. A.

doi:10.1016/0012-821x(73)90105-2

Cited by 40 publications

(16 citation statements)

References 22 publications

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“…1972;Steinhauser & Vincenz 1973). The main features of the reversal process are reduction of the field strength and an increase of the dispersion in direction of magnetization including swinging of the field.…”

Section: Introductionmentioning

confidence: 97%

Palaeomagnetic record of a late Tertiary field reversal

Dodson¹,

Dunn²,

Fuller³

et al. 1978

Geophysical Journal International

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A palaeomagnetic record of a field reversal has been obtained from the Tatoosh intrusion in Mount Rainier National Park (latitude 46" SO", longitude 121" 45'W). f i e VGP before and after the reversal is conformable with the North American polar wander curve. The reversal in direction is preceded by a decrease in intensity of the NRM of more than an order of magnitude. Immediately prior to the reversal the dispersion of the directions of magnetization increases. The reversal in direction is accomplished by a convoluted VGP path which traverses the Pacific and is somewhat confined in longitude. Subsequent to the completion of the change in direction the field intensity recovers, so that the intensity change takes at least twice as long as the directional change.The definition of the reversal plane in the Tatoosh intrusion gives the orientation of the cooling front at the time the reversal took place. An analysis of the cooling history of the body, in conjunction with the magnetic results, suggests that the body did not cool by simple conduction, and that convective heat transfer by meteoric water is important. This defines a twostage cooling of the margin. At high temperature rapid cooling takes place as the water chills the hot rock. Later the circulating water in the cracked permeable margin maintains a moderate temperature for long periods.Long vertical cores from the intrusion have revealed a palaeomagnetic record similar to present secular variation records and suggests that some tens of metres of core from intrusive similar to the Tatoosh could give important resolution records of the geomagnetic field. 3 74 R. Dodson et al.A second reversal record was obtained from the Laurel Hill intrusion near Mount Hood, Oregon (latitude 45" 20'N, longitude 121"4'W) which is approximately 10 Myr younger. The smoothed VGP paths for the two reversals are essentially identical. Other R + N paths from North America appear to favour the Pacific, although the Lake Tecopa record of the last reversal is a notable exception. In comparing all available reversal paths, one finds that although individual paths are confined in longitude, no longitude is uniquely preferred nor does the site uniquely determine a path longitude. There is some preference amongst R + N paths to favour the Pacific and the N + R the Euroasian landmass, but the limited distribution of observation sites precludes a satisfactory distinction between site control or absolute control in geographical coordinates.Dominantly quadrupolar transitional fields are consistent with the records. Such fields are predicted by a variant of the Steenbeck Krause DC dynamo, but aw dynamos may also exhibit quadrupolar transitional fields as indeed does the Sun. Some stationary nonaxisymmetric component is required to explain non-zero declination of the observed transitional fields.

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Section: Introductionmentioning

confidence: 97%

Palaeomagnetic record of a late Tertiary field reversal

Dodson¹,

Dunn²,

Fuller³

et al. 1978

Geophysical Journal International

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“…The existing earlier concept that during this process the pole moves in the limits of certain section of the globe (Steinhauser and Vincenz, 1973) has not been confirmed by calculation of the VGP trajectories for results from different parts of the world (Opdyke et al, 1973;Gurary, 1973). Thus, Opdyke and others (1973) ascertained that the trajectories of virtual poles for a set of consecutive events, Olduvai/Matuyama/ Jaramillo/Matuyama determined for an Indian Ocean core, differ considerably from each other and from the preferred trajectory suggested by Creer and Ispir (1970).…”

Section: The Characteristics Of the Process Of Polarity Changes (Accomentioning

confidence: 91%

Whole-Core Spinning and Detection of Reversal Boundaries in Hydraulic Piston Cores from the Southwestern Atlantic: Leg 72

Suzyumov¹,

Hamilton²

1983

Initial Reports of the Deep Sea Drilling Project, 72

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A study has been made of downhole declination changes of the horizontal component of the natural remanent magnetization of unopened whole-core sections recovered by use of the hydraulic piston corer at DSDP Sites 515,517, and 518. There is clear evidence that polarity reversal boundaries can be detected by this preliminary paleomagnetic technique. The Quaternary through late Neogene sediments studied reveal a record of the magnetostratigraphy over the past 4.5 Ma, although the quality of this record is better defined by the terrigenous sediments of the Brazil Basin than the biogenous oozes of the Rio Grande Rise.

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“…Polarity changes by a flip over of the dipole axis seem to have occured several times in the earth's history [15,16] and have also been observed in Upper Cretaceous rocks on Jamaica [9]. Low latitude or equatorial pole positions can be taken as the instantaneous records of the non-axial dipole configuration during such a type of field reversal.…”

Section: Paleomagnetic Pole Positionsmentioning

confidence: 99%