Absolute paleointensity of the Earth's magnetic field during Jurassic: case study of La Negra Formation (northern Chile) |
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Authors: | Juan Morales Avto Goguitchaichvili Luis M. Alva-Valdivia Jaime Urrutia-Fucugauchi |
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Affiliation: | Laboratorio de Paleomagnetismo y Geofisica Nuclear, Instituto de Geofisica, UNAM, Ciudad Universitaria, 04510 México DF, Mexico |
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Abstract: | We carried out a detailed rock-magnetic and paleointensity study of the ~187-Ma volcanic succession from northern Chile. A total of 32 consecutive lava flows (about 280 oriented standard paleomagnetic cores) were collected at the Tocopilla locality. Only 26 samples with apparently preserved primary magnetic mineralogy and without secondary magnetization components were pre-selected for Thellier paleointensity determination. Eleven samples coming from four lava flows yielded reliable paleointensity estimates. The flow-mean virtual dipole moments range from 3.7±0.9 to A m2). This corresponds to a mean value of (5.0±1.8)×1022 A m2, which is in reasonably good agreement with other comparable quality paleointensity determinations from the Middle Jurassic. Given the large dispersion and the very poor distribution of reliable absolute intensity data, it is hard to draw any firm conclusions regarding the time evolution of the geomagnetic field. To cite this article: J. Morales et al., C. R. Geoscience 335 (2003). |
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Keywords: | paleointensity paleomagnetism Jurassic northern Chile paléointensité paléomagnétisme Jurassique Nord-Chili |
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