A new Siberian record of the ∼1.0 Gyr-old Maya superchron

Abstract

We report new magnetostratigraphic data from the Late Mesoproterozoic Linok Formation consisting of clayed carbonates, together with paleomagnetic data from the Neoproterozoic carbonate Sukhaya Tunguska, Burovaya and Turukhansk formations, located in the Turukhansk region (northwestern Siberian platform). We also re-analyzed demagnetization data previously obtained from the Derevnya Formation. Paleomagnetic analyses revealed up to four magnetization components. First, a steep-inclination component, likely of recent origin, is isolated in all sections in the low temperature range. Second, a magnetization is recovered in most samples between ∼250 °C and ∼350–400 °C. It shows a single magnetic polarity and is interpreted as a remagnetization acquired during the Kiaman Permo-Carboniferous reverse superchron. Third, a magnetization component is isolated between ∼400 °C and ∼500 °C in samples from the Burovaya and Turukhansk formations. This component is interpreted as a remagnetization that occurred before the end of the Neoproterozoic. A fourth high-temperature (HT) magnetization component is observed up to ∼575 °C in samples from the Linok and Burovaya formations and up to ∼680 °C for those of the Derevnya and Turukhansk formations. A series of magnetic polarity reversals is observed in the lower and middle parts of the Linok Formation, whereas a single polarity interval is found in its upper part. The syn-depositional origin of this magnetization is attested by positive reversal, conglomerate and fold tests. The HT magnetization component isolated in the Derevnya and Burovaya formations shows a single magnetic polarity. Its primary origin is supported by the fact that the Derevnya and Burovaya HT mean directions are positioned in the continuity of the directional evolution observed through the Linok Formation. It is further constrained by very consistent Late Mesoproterozoic to Early Neoproterozoic apparent polar wander paths obtained from different regions of the Siberian platform. A single magnetic polarity reversal is observed in a ∼40 m-thick section of the Turukhansk Formation. The HT directions found in the upper part of the Linok Formations, over a stratigraphic thickness of ∼200 m, and in the Derevnya and Burovaya formations strengthen the existence of the normal polarity Maya superchron around 1.0 Ga, at the transition between the Mesoproterozoic and the Neoproterozoic.