Y. Gallet et V. Pavlov, MAGNETOSTRATIGRAPHY OF THE MOYERO RIVER SECTION (NORTH-WESTERN SIBERIA) - CONSTRAINTS ON GEOMAGNETIC REVERSAL FREQUENCY DURING THE EARLY PALEOZOIC, Geophysical journal international, 125(1), 1996, pp. 95-105
We present the magnetostratigraphy of the early Palaeozoic Moyero rive
r section in north-western Siberia. The section investigated, which co
nsists mainly of reddish limestones, marls and greyish limestones, ext
ends from the upper Cambrian to the lower Silurian. Palaeomagnetic ana
lyses reveal two magnetic components. One is interpreted as a remagnet
ization acquired during Siberian trap emplacement; the other is believ
ed to be early diagenetic, consistent with the established lower Palae
ozoic apparent polar wander path for Siberia. Reversed polarity domina
tes from the upper Cambrian to the middle Ordovician, while normal pol
arity dominates from the upper Ordovician to the lower Silurian. Only
a few reversals, which are poorly defined, are observed through the se
ction, in particular during the Llandeilo. These data are in agreement
with previous magnetostratigraphic data from the Baltic platform and
Siberia and indicate that magnetic reversal frequency was low during t
he Ordovician. Because of the time-delayed process of acquisition of t
he magnetization carried by haematite, we cannot clearly ascertain if
a reversed superchron occurred during the lower to middle Ordovician.
However, our results suggest that a 15 Myr-long reversed interval exis
ted during the Arenig.