We present new geochronological and palaeomagnetic results from the late Palaeoproterozoic Akitkan Group in South Siberia. The zircon U–Pb conventional age of the rhyodacite from the upper part of the group is 1863±9 Ma and the age of the dacite from the lower part of the group is 1878±4 Ma. Palaeomagnetic study of sedimentary and some igneous rocks from the upper part of the group isolated a high-temperature characteristic component (D=193°, I=19°, k=51, α95=7°) which is supported by two of three applied conglomerate tests. However, the third intra-formational conglomerate test demonstrates a contaminating overprint of uncertain nature for a part of our collection. The analysis of data suggests that this overprint occurred at time when the geomagnetic field's direction was similar to that at the time of the deposition. Therefore the corresponding palaeomagnetic pole (22.5 °S, 97.4 °E, dp=1.5°, dm=2.8°) may be considered as representative for the deposition time. Palaeomagnetic study of the sediments in the lower part of the Akitkan Group isolated a stable primary remanence (D=189°, I=8°, k=111, α95=5°) supported by positive intra-formational conglomerate and fold tests. The palaeomagnetic pole (30.8 °S, 98.7 °E, dp =2.5°, dm=5.0°) is nearly coeval with the 1879 Ma Molson B pole from the Superior craton. We used these two poles to compare the relative position of Siberia and the Superior craton in the late Palaeoproterozoic. It is different from their reconstruction around 1000 Ma. This demonstrates their relative movements in the Mesoproterozoic.

With U-Pb zircon dating, we determined the age of rhyodacites composing sedimentary covers among coarse-terrigenous rocks of the lowermost Chaya Formation of the Akitkan Group (North Baikal volcanoplutonic belt). These rocks are considered to have formed during the sedimentation. The dates (1863±9 Ma) permitted estimation of the age of basal beds of the Chaya Formation and substantiate the age boundary between the Khibelen and Chaya Formations of the Akitkan Group. The determined age and earlier dates of igneous rocks intruding the Chaya Formation deposits suggest that the latter accumulated for ~10 Myr.

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