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[1] Paleomagnetic results from an Upper Vendian sedimentary sequence exposed along the White Sea shoreline, NW Russia are described. These classical exposures have been the subject of intense paleontological investigations due to their well-preserved Ediacara fauna, but no paleomagnetic results have as yet been published. A total of 337 hand samples and 210 oriented drill cores (35 sites) along three profiles have been collected at the locality (65.5°, 40.0°E) where a 555 ± 3 Ma U-Pb age of comagmatic zircons from volcanic ash layers has been recently obtained. Standard paleomagnetic procedures yield two main natural remanent magnetization (NRM) components: an intermediate-temperature (150°-350°C), single-polarity component (D = 121°, I = 72°, n = 232 samples, k = 46.0, a 95 = 1.3°, pole position at 40.0°N, 79.0°E, dp = 2.0°, dm = 2.3°) and a high-temperature (550°-680°C) dual-polarity component (normal polarity: D = 278°, I = 43°, n = 54 samples, k = 25.2, a 95 = 3.9°, reversed polarity: D = 101°, I = À39°n = 40, K = 23.3, a 95 = 4.8°, south pole position at 24°S, 132°E, dp = 2.3°, dm = 3.8°). This latter component, termed Z, passes reversal, stratigraphic, and consistency tests and is interpreted to reflect the direction of the Earth's magnetic field during Late Vendian times. These results put Baltica into low northern latitudes (between 10°and 35°) and the resulting pole position requires modification of the most recent Apparent Polar Wander Paths (APWP) for Baltica.

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Palaeomagnetic and petromagnetic studies were carried out in two sections of the Late Vendian-Early Cambrian rocks in the southeastern White Sea region. Ninety meters of the Zolotitsa River section (350 oriented lump samples from the outcrops) and 420 m of core samples from the Verkhotina Hole (443 samples) were studied. Two absolute age values are available for the lower part of the Zolotitsa River section: 550±4.6 Ma and 550±5.3 Ma. These ages were determined using zircons from the volcanic rock interlayers. The rocks investigated in this study are characterized by the low anisotropy of magnetic susceptibility, by the absence of any predominant directions of the half-axes of the ellipsoids of anisotropy, and by the planar type of the latter. The main carrier of natural remanent magnetization (NRM) is hematite in all rocks, magnetite being found occasionally in gray rocks. The detailed stepwise thermal demagnetization of the samples proved the multicomponent composition of the rocks. The low-and medium-temperature components resulted from the demagnetization of the rocks during various interval of geologic time. The high-temperature component is characterized by the positive tests of folding, reversal, and correlation, hence being a primary one. Variations of its direction along the rock sequence were used in this study to identify 27 zones of direct and 28 zones of reversed polarity for the total amount of the rocks investigated in this study. The most reliable results were used to plot the alternative trajectory of the Baltic palaeomagnetic pole migration for the Vendian time and to reconstruct the palaeogeographic Baltic position for that time. A new method was offered and tested for orienting borehole samples in space. Its application was found to produce the high convergence of the results, both in the case of the natural outcrops and borehole samples.

The Quaternary history of Beringia and of the Arctic-Pacific marine connection via the Bering Strait is poorly understood because of the fragmentary stratigraphic record from this region. We report new borehole and seismic-reflection data collected in 2006 in the southwestern Chukchi Sea. Sediment samples were analyzed for magnetic properties, grain size, heavy minerals, and biostratigraphic proxies (spores and pollen, foraminifers, ostracodes, diatoms, and aquatic palynomorphs). Two shallow boreholes drilled between the Chukotka Peninsula and the Wrangel Island recovered sediments of two principal stratigraphic units with a distinct unconformity between them. Based on predominantly reverse paleomagnetic polarity of the lower unit and pollen spectra indicative of forested coasts and climate warmer than present, the age of this unit is estimated as Pliocene to early Pleistocene (broadly between ca. 5 and 2 Ma). Attendant sedimentary environments were likely alluvial to nearshore marine. These deposits can be correlated to the seismic unit infilling valleys incised into sedimentary bedrock across much of the study area, and possibly deposited during a transgression following the opening of the Bering Strait. The upper unit from both boreholes contains Holocene 14 C ages and is clearly related to the last, postglacial transgression. Holocene sediments in Borehole 2 indicate fast deposition at the early stages of flooding (between ca. 11 and 9 ka) to very low deposition, possibly related to expansive sea ice. Closer to shore, deposition at Borehole 1 resumed much later (ca. 2 ka), likely due to a change in the pattern of coastal erosional processes and/or the demise of a landbridge between the Chukotka Peninsula and the Wrangel Island inferred from studies on mammoth distribution.

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