Magnetostratigraphy of the Moyero river section (north-western Siberia): constraints on geomagnetic reversal frequency during the early Palaeozoic

Yves Gallet ' (1) , Vladimir Pavlov (2)

1 IPGP - Institut de Physique du Globe de Paris
2 IPE - Schmidt United Institute of Physics of the Earth [Moscow]

We present the magnetostratigraphy of the early Palaeozoic Moyero river section in northwestern Siberia. The section investigated, which consists mainly of reddish limestones, m a r k and greyish limestones, extends from the upper Cambrian to the lower Silurian. Palaeomagnetic analyses reveal two magnetic components. One is interpreted as a remagnetization acquired during Siberian trap emplacement; the other is believed t o be early diagenetic, consistent with the established lower Palaeozoic apparent polar wander path for Siberia. Reversed polarity dominates from the upper Cambrian to the middle Ordovician, while normal polarity dominates from the upper Ordovician to the lower Silurian. Only a few reversals, which are poorly defined, are observed through the section, in particular during the Llandeilo. These data are in agreement with previous magnetostratigraphic data from the Baltic platform and Siberia a n d indicate that magnetic reversal frequency was low during the Ordovician. Because of the time-delayed process of acquisition of the magnetization carried by haematite, we cannot clearly ascertain if a reversed superchron occurred during the lower t o middle Ordovician. However, our results suggest that a 15 Myr-long reversed interval existed during the Arenig.

Mots clés: magnetostratigraphy; Ordovician; reversal frequency; Siberia; superchron

Domaines: Géophysique [physics.geo-ph]; Stratigraphie

Yves Gallet ', Vladimir Pavlov. Magnetostratigraphy of the Moyero river section (north-western Siberia): constraints on geomagnetic reversal frequency during the early Palaeozoic. Geophysical Journal International, 1996, 125 (1), pp.95-105. ⟨10.1111/j.1365-246X.1996.tb06536.x⟩. ⟨insu-01863442⟩