Paleomagnetic full vector record of four consecutive Mid Miocene geomagnetic reversals

J. Linder , R. Leonhardt

Seventy Mid Miocene lava flows from flood basalt piles near Neskaupstadur (East Iceland) were sampled, which provide a quasi-continuous record of geomagnetic field variations. Samples were collected along the Profile B of Watkins and Walker (1977), which was extended about 250 m farther down in a neighboring stream bed. Published radiometric age determinations (Harrison et al., 1979) range from 12.2 to 12.8 Ma for the sampled sequence. Four reversals were recorded in this profile, with 18 transitional lavas found within or between 17 normal and 30 reversed polarity flows. The large amount of transitional lavas and the large virtual geomagnetic pole dispersion for stable field directions are noteworthy as such features are commonly observed in Icelandic lavas and manifest in a far-sidedness of the average VGP. The reason for this characteristic, which could be related to an anomaly beneath Iceland, a global field phenomenon, local tectonics, and/or non-horizontal flow emplacement, is scrutinized. Non-horizontal flow emplacement is likely in volcanic environments particularly if the sampled lavas are located on the paleoslopes of a central volcano.

Mots clés: Paleomagnetism; absolute paleointensity; Eastern Iceland; Mid Miocene; Geomagnetic reversals

J. Linder, R. Leonhardt. Paleomagnetic full vector record of four consecutive Mid Miocene geomagnetic reversals. Physics of the Earth and Planetary Interiors, 2009, 177 (1-2), pp.88. ⟨10.1016/j.pepi.2009.07.013⟩. ⟨hal-00585470⟩