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The results of paleomagnetic studies and paleointensity determinations from two Neoarchaean Shala dikes with an age of ~2504 Ma, located within the Vodlozerskii terrane of the Karelian craton, are presented. The characteristic components of primary magnetization with shallow inclinations I = −5.7 and 1.9 are revealed; the reliability of the determinations is supported by two contact tests. High paleointensity values are obtained by the Thellier-Coe and Wilson techniques. The calculated values of the virtual dipole moment (11.5 and 13.8) × 10 A m are noticeably higher than the present value of 7.8 × 10 A m. Our results, in combination with the previous data presented in the world database, support the hypothesized existence of a period of high paleointensity in the Late Archaean-Early Proterozoic. [ABSTRACT FROM AUTHOR]

Results of palaeointensity and palaeomagnetic studies for the volcanic rocks of 1450 Ma, from Early Riphaean Baltic shield dyke complex sampled in Lake Ladoga region (Karelia, Northwestern Russia) are reported. Electron microscope observations, thermomagnetic and hysteresis measurements indicate the presence of single domain (SD) to pseudo-single domain (PSD) titanomagnetite (TM) with low Ti content as the main magnetic mineral. Stepwise alternating field (AF) and/or thermal demagnetization revealed a two-component natural remanent magnetization (NRM) for most of the samples. The characteristic remanent magnetization (ChRM) component was isolated between 440 and 590 °C. Note that the ChRM amounts to 95 per cent of the NRM intensity. The geographic position of the ChRM palaeopoles does not contradict the ‘key poles’ of the [1270; 1580] Myr time interval, testifying anticlockwise rotation of whole East Europe Craton between 1450 and 1500 Ma. Palaeointensity determinations were performed by Coe-modified Thellier procedure. 35 samples passed our palaeointensity selection criteria and show large linear segments on Arai-Nagata plots. The site mean virtual dipole moment (VDM) varies from 2.00 to 3.91 (× 1022 A m2). Based on these and other observations, we suggest that the Palaeo- and MezoProterozoic was dominated by low VDMs. [ABSTRACT FROM AUTHOR]