Refined Late Mezoproterozoic Paleomagnetic Pole for the Siberian Platform and Further Evidence for New Superchron around the Mesoproterozoic-Neoproterozoic Transition from the Magnetostratigraphy of the Linok Formation

We present new magnetostratigraphic data obtained from the late Mesoproterozoic ( about 1,05 Ga) Linok Formation in the Turukhansk region of the Siberian platform. A 70-150 m-thick sections encompassing upper part of the carbonate-terrigenous Linok Formation was densely sampled in 3 several tens kilometers away outcrops located along the valley of Nizhnjaja Tunguska and Sukhaya rivers (northwestern Siberian platform). Paleomagnetic analyses revealed generally the existence of two magnetization components. A low unblocking temperature component, which likely has a viscous origin, was first isolated below 200°C. A characteristic component (ChRM), carried, apparently, by magnetite, was then isolated in the medium to high temperature range (up to 585- 600°C). This component has only reversed polarity. A positive paleomagnetic conglomerate test indicates with certainty that the ChRM was acquired during or very soon after sediment deposition. Occasionally we observed third, the middle temperature component with unblocking temperatures between 250 and 400°C. This component has been presumably formed at Middle-Late Paleozoic during tectonic events, accompanying the closure of the Paleoasian ocean, at the western (modern) margin of the Siberian platform. Mean paleomagnetic direction obtained in this study for the ChRM of the Linok Fm yields new ~1000 Ma paleomagnetic pole for this part of the Siberian platform which refines the paleomagnetic pole, published by us earlier (Gallet et al., 2000). Furthermore, occurrence of hundred-meters scale long interval of reversed polarity in the studied sections supports the existence of the geomagnetic superchrone (Maya superchrone - [Gallet et al., 2012]) around the Meso -Neoproterozoic transition.