Vol 31, No 3 (2023)

Petrogeochemical features of the Vodorazdelny massif granites (Subpolar Urals, Lyapinsky anticlinorium) indicate these rocks are close to I-granites and were formed in suprasubduction environment. The ratios of the key elements (Rb, Ba, Th, Sr, Y, Nb) suggest that the basites of the melting slab and the fluid separated during their dehydration could participate in the granite generation. The U–Pb age of the main population of magmatogenic zircons is 593 ± 4 Ma and corresponds to the Vendian (Ediacarian). It coincides with the age of the granites from the nearby Vangyr massif (598 ± 5 Ма), as well as with the age of zircon cores from the granites of the Kozhim massif located to the north. Values of ε_Hf(t) from –2 to 0 in magmatogenic zircons with an age corresponding to the age of Vodorazdelny granites indicate a heterogeneous source of melts. The zircons of these granites also contain ancient cores with U–Pb ages from 2200 to 700 Ma, where the values of ε_Hf(t) from +0.8 to +13 indicate the presence of a crust component in the substrate (the substance of the ancient platform basement). Petrogeochemical and isotope-geochronological parameters of granites (and their zircons) do not confirm the validity of attributing of Vodorazdelny granite massif (and its analogues – the Vangyr and Kozhim massifs) to the Cambrian Salner-Mankhambo complex. We consider there are the possibility of separating of independent complex (about 598 Ma, Vendian?) during geological mapping. The presence in the Lyapinsky anticlinorium of several stages of granite generation (Middle Riphean–Vendian–Cambrian), accompanied by metamorphism, and complicate composition of ancient metamorphic strata from this structure basement led to varying isotopic parameters characterizing the heterogeneity of the source of melts, on the one hand, and the convergence of a number of geochemical features, on the other.

Starting from the mid-Cretaceous and in the Late Cretaceous, the landscape features of the North Pacific make it possible to divide this region into a number of territories called subregions. The earliest Cenophytic (with a significant number and diversity of angiosperms) Late Albian–Early Turonian Grebenka flora and its analogs are known only in three subregions of the North Pacific: Anadyr-Koryak, Northern Alaska and Yuk-on-Koyukuk. In the middle of the Cretaceous these subregions were represented by coastal plains and lowlands periodically flooded by the sea. Cenophytic floras populated the area of terrestrial volcanism of the Okhotsk–Chukotka subregion and the Asian continental interiors of the Verkhoyansk–Chukotka subregion later, in the Turonian–Coniacian, but Mesophytic vegetation with the predominance of Early Cretaceous ferns and gymnosperms continued to exist there at least until the Coniacian. Consequently, the invasion of evolutionarily new Cenophytic vegetation into the continental interiors of North-Eastern Asia was gradual and extended over time. This should be taken into account when studying the Cretaceous nonmarine phytostratigraphy of the North Pacific region.

The article presents the results of the study of continental palynomorphs from the amber-bearing Upper E-ocene deposits in the Primorsky quarry (Kaliningrad Oblast, southeastern coast of the Baltic Sea). Three spore and pollen assemblages were identified and calibrated with the dinoflagellate cyst Rhombodinium perforatum and Thalassiphora reticulata zones. The “Blue Earth” Member of the Prussian Formation of the early Priabonian age is characterized by the Tricolporopollenites exactus–T. retiformis–Quercoidites microhenrici assemblage. The upper Priabonian “Upper Quicksand” and “White Wall” members of the Prussian Formation and the Palvé Formation are characterized by the Platanipollis ipelensis–Castaneoideaepollis oviformis–Tricolpopollenites foraminatus assemblage. The Inaperturopollenites–Sciadopityspollenites–Sequoiapollenites assemblage was recognized in the uppermost Palvé and lowermost Kurshskaya formations of the terminal Priabonian age. During the late Eocene the climatic conditions on the territory of the modern southern Baltic area were quite warm and humid, close to subtropical ones. Mixed coniferous-broad-leaved forests grew along the shores of the marine paleostrait, while the open spaces were occupied by heat-loving evergreen and moderately heat-loving deciduous shrubs and low-lying land areas were swamped. At the end of the Priabonian, a gradual regression of the sea basin began, which led to an increase in swampy areas on land, while the climate was still quite warm and humid.

The main critical remarks to the paper by M.G. Moiseeva, A.B. Herman, A.B. Sokolova entitled “On the Stratigraphic Setting and Composition of the Ayanka Flora from the Upper Cretaceous of Okhotsk-Chukotka Volcanogenic Belt, Northeastern Russia” (Stratigraphy and Geological Correlation, 2022, vol. 30, No. 4, pp. 76–99), stated by S.V. Shczepetov in his article “On the Ayanka flora from the Upper Cretaceous of Northeastern Russia” (Stratigraphy and Geological Correlation, 2022, vol. 30, No. 6, pp. 113–120), are considered. Additional arguments are given to confirm the conclusions we’ve made earlier: (1) all three taphofloras from the Obryvistaya River basin came from a single straton; it however was named differently on two separate sheets of the 1:200000 State Geological Map: the Auney Member on the northern sheet and the Makkoveyem Formation on the southern one; (2) according to the composition of the plants of these taphofloras, all of them are about of the same age and can be considered as a single Ayanka Flora; (3) the most probable age of the Ayanka Flora is Santonian-Campanian, since it is undoubtedly the most similar to the Santonian-Campanian floras of Northeastern Russia and Northern Alaska.