In Earth’s geological evolution the Vendian is significant because: 1) it preceded the «Cambrian Evolutionary explosion» when the multicellular organisms became suddenly much more diverse; 2) it is associated with the global tectonic and palaeogeographic restructuring of supercontinents, a change in geomagnetic field generation and other global processes affecting different layers of the Earth. At the same time, recent publications indicate an extremely irregular behavior of the geomagnetic field in the Vendian, which significantly differs from the recent regime of the geomagnetic field generation. New information on the configuration and magnitude of the geomagnetic field is crucial for understanding the reasons that can cause different modes of geodynamo. The article describes the new results of palaeomagnetic studies of the Volyn traps — basalts and tuffs of the Volyn series with ages about 560—580 My. The determined palaeodirections and palaeopoles are in good agreement with the previously published data of other authors and substantially complement them. The ChRM-component of «low-titanium» basalts was isolated in high-temperature (>500 °C) and characterized as primary. The same samples were used for palaeointensity determinations which showed the extremely low values of the geomagnetic field — an order of magnitude lower than the present one. The ChRM-component of «high-titanium» basalts was yielded in the temperature range of 200—400 °C. No results were obtained from palaeointensity experiments, and the complex nature of remanent magnetization remains unclear. The new data are compared with the palaeo-magnetic data of the Vendian—Early Cambrian poles of the East European Platform determined by other authors. To test the hypothesis of an anomalous Ediacaran magnetic field characterized by a low dipole moment and a high inversion frequency, more data are necessary. These data can be obtained from the studies of a stratigraphically more complete section of the Volyn traps opened by boreholes. These results will be presented in the next part of the article.

Variations of rock magnetic parameters in loess-palaeosol sequences, related to climatic and environmental conditions during their formation, are a powerful tool for palaeoclimate reconstruction. Combined enviromagnetic study of loess deposits in Ukraine and its assessment for the palaeoreconstruction purposes are carried out in the framework of the National Research Foundation of Ukraine project 2020.02/0406 ‘Magnetic proxies of palaeoclimatic changes in the loess-palaeosol sequences of Ukraine’. Environmental/climatic reconstructions of the past are fulfilled using a significant number of palaeoindicators: morphology and lithological properties of palaeosols and loesses, their pollen assemblages and a wide range of magnetic characteristics. In this paper, we present a multi-proxy approach to palaeoenvironmental reconstructions, and introduce preliminary results obtained from magnetic susceptibility of loess-palaeosol sequences in the northern (at Vyazivok), central (Stari Kaydaky) and southern (Roksolany) parts of the Ukrainian loess belt. The amplitudes of palaeoclimate change established using magnetic proxies are well correlated with the lithological, palaeopedological and palynological patterns of the sites, and with the global oxygen-isotope scale (MIS). Ongoing studies of the Stari Kaydaky section confirm the correlation of the Upper Zavadivka (S3) soil unit and Lower Zavadivka (S4) soil unit with MIS 9 and MIS 11, respectively (this was proved earlier at the Vyazivok and Roksolany sites). The underlying Lubny (S5) pedocomplex likely corresponds to MIS 13, and the Martonosha (S6) pedocomplex to MIS 15. Palaeomagnetic investigations at Stari Kaydaky have not so far reached the Lower Shyrokyne unit, in which the Matuyama—Brunhes boundary has been detected at Roksolany and Vyazivok. The Upper Shyrokyne (S7S1) palaeosol unit has normal polarity and is preliminarily correlated with MIS 17.

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<p>A combined pedostratigraphic and rock magnetic study of four loess-palaeosol sequences in the Middle Dnieper area, Ukraine (at Gunky, Zamozhne, Vyazivok and Stari Kaydaky) have been performed in order to determine the suitability of these sites for rock magnetic cyclostratigraphy and the establishment of magnetostratigraphic markers. Two geomagnetic events – the Matuyama/Brunhes boundary (at 780 ka) and Unnamed excursion (at 430 ka) – have been detected at the long Vyazivok loess-paleosol record (Hlavatskyi et al., 2016; Hlavatskyi and Bakhmutov, 2020). The till of the Dnipro glaciation (MIS 6) and the corresponding thick loess (U-L2), present in all sections, and faunal remains at the Gunky section, typical for MIS 11 (Markova, 2004), serve as reliable age benchmarks for developing a comprehensive cyclostratigraphic model. The studied sections are most similar by their rock magnetic and palaepedological characteristics to the Hungarian loess-palaeosol sequences (Udvari-U2 and Paks), which are also located in the temperate climatic zone. These sections can be related to the «Chinese» type of formation of magnetic properties, with very low magnetic susceptibility values in loesses and higher values in palaeosols. However, the magnetic susceptibility pattern in palaeosols of northern Ukraine is distorted by the later cryoturbation and gleying processes of the subsequent cold phases. In contrast to the Chinese, Danube and southern Ukrainian loess sequences, these sites are characterized by much lower concentration of ferrimagnetic material, especially in the Lubny (U-S5, correlative of MIS 13) and Potyagaylivka (U-S2/MIS 7) palaeosols. The highest magnetic enhancement is characteristic for the Lower Zavadivka (U-S4/MIS 11), Upper Zavadivka (U-S3/MIS 9) and, in part, the Pryluky­-Kaydaky (U-S1/MIS 5) pedocomplexes. Rock magnetic investigations show predominance of pseudo-single domain magnetite in palaeosols and higher proportion of hematite in loesses. It is suggested that wet conditions in northern Ukraine, which periodically appeared due to its closeness to the ancient ice fronts, facilitated the oxidation of ferrimagnetic grains and the formation of high coercive minerals.</p><p><strong>Acknowledgements. </strong>The research was supported by the National Research Foundation of Ukraine grant 2020.02/0406 "Magnetic proxies of palaeoclimatic changes in the loess-palaeosol sequences of Ukraine".</p><p><strong>References:</strong></p><p>Hlavatskyi D.V., Kuzina D.M., Gerasimenko N.P., Bakhmutov V.G. 2016. Petromagnetism and palaeomagnetism of Quaternary loess-soil sediments of Vyazivok section (Dnieper Lowland). <span><em>Geofizicheskii Zhurnal</em> <em>(Geophysical Journal)</em>, 38 (6). 186-193. http://dx.doi.org/10.24028/gzh.0203-3100.v38i6.2016.91903</span></p><p>Hlavatskyi D.V., Bakhmutov V.G. 2020. Magnetostratigraphy and magnetic susceptibility of the best developed Pleistocene loess-palaeosol sequences of Ukraine: implications for correlation and proposed chronostratigraphic models. <em>Geological Quarterly</em>, 64 (3). 723–753. http://dx.doi.org/10.7306/gq.1544</p><p><em> </em>Markova, A.K. 2004. A reconstruction of the Lichvin interglacial paleolandscape based on material of small mammals from East Europe. <em>Izvestia RAS, Ser. Geography</em>, 2. 35–59. (in Rus.)</p>

<p>We present the results of palaeomagnetic study of Ediacaran terrigenous rocks from the SW part of East European Craton (EEC), Podolia (Ukraine). Samples are represented by red tufits of Grushkinska suite by Volhynian series, which is comparable to the upper part of the Ediacaran age by the international stratigraphic scale. Samples for paleomagnetic studies were taken at the reference section of the Grushkinsky suite of the Volhynia series in the village of Grushka (48.45°N 28°E). A total of 50 oriented core samples were selected. For the entire collection of samples, the standard procedure for paleomagnetic studies was applied. The samples underwent stepwise temperature demagnetization.  Demagnetization showed that all samples are completely demagnetized at a temperature close to 700°C. The results of demagnetization showed that additionally to the viscous components of the magnetization released up to 200°C, four more stable components of NRM are released: CLM-1–component, relatively low temperature, in the range of deblocking temperatures of 200–360°C. It is characterized by south-south-west declination and negative inclination (D/I = 197.9/-28.6); CLM-2–component, is allocated in the same temperature range as component CLM-1 (200-360°С), is characterized by south-south-west declination and positive inclination (D/I = 202.4/31); CMH–component, is strictly allocated in the range of unlocking temperatures of 590–630°C. It is characterized by northwestern declination and positive inclination (D/I = 311/18.9); CH –component, a bipolar high-temperature component, is released in the temperature range of 650–700°C. The middle direction of the forward and reverse polarity is characterized by north-north-west declination and positive inclination (D/I = 296.4/71.2). The directions of normal and reverse polarity of this component are closely antipodal and successfully pass the reversal test (γ/γ<sub>c</sub> = 7.85/8.82), class “B” in accordance with [McFadden & McElhinny, 1990].</p><p>The coordinates of the virtual geomagnetic poles for the two low-temperature components, respectively, are located close to the Permian (Φ/Λ = -53.7/357.9) and Silurian part (Φ/Λ = -21.8/4.9) of the apparent polar wander path for the EEC [Torsvik et al., 2012]. The VGP, calculated from the middle-high-temperature component, is located in the Caribbean region (Φ/Λ = 33.8/271.4) and the VGP for the relatively high temperature component is located in the eastern part of the North Atlantic (Φ/Λ = -52.5/149.1) that close to the another paleomagnetic determinations with ages about 550 Ma and 570 Ma respectively for different parts of EEC.</p><p>New data demonstrate the palaeomagnetic information content of the studied rocks and the possibility of their more detailed study in order to analyze anomalous palaeomagnetic data in the ediacaran and study the evolution of the Earth's geomagnetic field.</p><p>The analysis of directions and poles indicates that the paleomagnetic results do not contradict the data on the extremely high variability of the geomagnetic field in the studied time interval.</p><p>The new paleomagnetic determinations correspond to the previous results obtained by other authors for different regions of the East European platform, thereby supplementing them.</p>