Periodicity of magnetic intensities in magnetic anomaly profiles: the Cretaceous of the Central Pacific |
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| Authors: | Iorio Tarling & D'Argenio |
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| Institution: | Geomare sud, Research Institute, CNR, Via Vespucci 9, Napoli, Italy;Department of Geological Sciences, University of Plymouth, Drake Circus, Plymouth, PL4 8AA, UK. E-mail:;Dipartimento Scienze della Terra, University of Napoli, Largo San Marcellino 10, Napoli, Italy |
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| Abstract: | Spectral analyses of long magnetic anomaly profiles of Cretaceous age in the Phoenix and Hawaiian lineations within the Pacific Basin show two to five non-harmonic wavelength peaks, with probabilities >90 per cent, within the range of several tens to hundreds of kilometres for each profile. For each profile with four peak wavelengths, their ratios correlate strongly ( r > 0.98) with the ratios for the Earth's orbital eccentricity periodicities for this time, and hence the profile peaks necessarily correlate with each other. These observations suggest that the magnetic anomaly signal is influenced by the Earth's changing orbital parameters, probably through their influence on the internal geomagnetic field. This implies that assumptions usually made to convert the magnetic signal to the magnetization of the oceanic crust may be suspect. The observations, if confirmed, indicate that orbital periodicities can assist in improving the age calibration of the global polarity timescale and that the predicted orbital behaviour of the Earth is confirmed for the last 150 Ma. |
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| Keywords: | Cretaceous geomagnetic reversals geomagnetism magnetic anomalies orbital cycling |
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