PALEOMAGNETISM OF LOWER CAMBRIAN SEDIMENTS FROM THE OLENEK RIVER SECTION (NORTHERN SIBERIA) - PALEOPOLES AND THE PROBLEMS OF MAGNETIC POLARITY IN THE EARLY CAMBRIAN

New palaeomagnetic data from the Lower and Middle Cambrian sedimentary rocks of northern Siberia are presented, During stepwise thermal dema gnetization the stable characteristic remanence (ChRM) directions have been isolated for three Cambrian formations, Both polarities have bee n observed, and mean ChRM directions (for normal polarity) are: Kessyu sa Formation (Lower Cambrian) D = 145 degrees, I = -40 degrees, N = 12 , alpha(95) = 12.8 degrees; pole position: Phi = 38 degrees S, Lambda= 165 degrees E; Erkeket Formation (Lower Cambrian, stratigraphically hi ghly) D = 152 degrees, I = -47 degrees, N = 23, alpha(95)=6.8 degrees; pole position: Phi=45 degrees S, Lambda=159 degrees E; Yunkyulyabit-Y uryakh Formation (Middle Cambrian) D = 166 degrees, I = -33 degrees, N = 38, alpha(95) = 4.6 degrees, pole position: Phi = 36 degrees S, L = 140 degrees E. These poles are in good agreement with the apparent po lar wander path based on the bulk of existing Cambrian palaeomagnetic data from the Siberian platform. In Cambrian times, the Siberian platf orm probably occupied southerly latitudes stretching from about 35 deg rees to 0 degrees, and was oriented 'reversely' with respect to its pr esent position. Siberia moved northwards during the Cambrian by about 10 degrees of latitude. This movement was accompanied by anticlockwise rotation of about 30 degrees. The magnetostratigraphic results show t he predominance of reversed polarity in the Early Cambrian and an appr oximately equal occurrence of both polarities in the part of the Middl e Cambrian studied. These results are in good agreement with the palae omagnetic polarity timescale for the Cambrian of the Siberian platform constructed previously by Khramov et al. (1987).