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The Central Asian Orogenic Belt (c. 1000-250 Ma) formed by accretion of island arcs, ophiolites, oceanic islands, seamounts, accretionary wedges, oceanic plateaux and microcontinents in a manner comparable with that of circum-Pacific Mesozoic-Cenozoic accretionary orogens. Palaeomagnetic and palaeofloral data indicate that early accretion (Vendian-Ordovician) took place when Baltica and Siberia were separated by a wide ocean. Island arcs and Precambrian microcontinents accreted to the active margins of the two continents or amalgamated in an oceanic setting (as in Kazakhstan) by roll-back and collision, forming a huge accretionary collage. The Palaeo-Asian Ocean closed in the Permian with formation of the Solonker suture. We evaluate contrasting tectonic models for the evolution of the orogenic belt. Current information provides little support for the main tenets of the one- or three-arc Kipchak model; current data suggest that an archipelago-type (Indonesian) model is more viable. Some diagnostic features of ridge-trench interaction are present in the Central Asian orogen (e.g. granites, adakites, boninites, near-trench magmatism, Alaskan-type mafic-ultramafic complexes, high-temperature metamorphic belts that prograde rapidly from low-grade belts, rhyolitic ash-fall tuffs). They offer a promising perspective for future investigations.

Palaeopascichnida is a problematic group of extinct organisms that is globally distributed in Ediacaran sequences of Avalonia, Baltica, Siberia, South China and Australia. The fossils related to Palaeopascichnida consist of serially or cluster-like arranged, millimetre- to centimetre-scale globular or allantoid chambers, which are characterized by substantial differences in preservation, leading to no consistent diagnosis for these organisms. Here we integrate morphometric variation, stratigraphic distribution and habitat settings of more than 1200 specimens from all known fossil localities. The results of the morphological analysis demonstrate variation in chamber shape and size, and allow us to recognize six valid species within the group. Statistical analysis of the specimen distribution with respect to sedimentary environments indicates a significant difference in palaeoecological settings between species, making a significant contribution to the evolution and systematic palaeontology of these problematic organisms and perspective on their use in Neoproterozoic biostratigraphy. Our revision and systematic study sheds new light on one of the least studied groups of the late Ediacaran biota.

U–Pb dating (LA-ICP-MS) is carried out on detrital zircon from pre-Middle Devonian terrigenous deposits of the Vychegda Trough (southern margin of the Mezen syneclise) penetrated by Seregovo 1, Storozhevsk 1, and Keltma 1 parametric wells. Analysis of the detrital zircon ages and subsequent calculations of maximum depositional age (MDA) based on different algorithms has made it possible to clarify the stratigraphic position of the studied successions. The deposits of the Nyafta Formation, penetrated by Seregovo 1 well, have Middle Riphean MDAs. The MDAs of the Uftyug Formation zircons correspond to the Middle-Late Riphean, and those of the Ust-Pinega Formation correspond to the Late Riphean. For the Mezen Formation, penetrated by Keltma 1 well, the calculated MDAs for the first time suggest an Early Cambrian or younger age.

Herein we present an integrated chemostratigraphic (δ 13 С and δ 18 O) and paleoichnological study of the Ust’-Tagul and basal Usol’e formations of the Biryusa Cis-Sayans Uplift (southwestern Siberian Platform). Positive carbon isotope excursion in the upper 34 m of the Ust’-Tagul Formation corresponds to ZHUCE anomaly in the composite δ 13 С curve and suggests Tommotian age of the host strata. Our data show the diachronous onset of the massive evaporitic sedimentation, marking the base of the Usol’e Regional Stage, in different paleobasins at the southwestern margin of the Siberian Platform. The isotope record of the Ust’-Tagul Formation lacks a profound negative excursion comparable to BACE anomaly. The lowermost appearance of burrows Treptichnus pedum 90 m above the base of the formation, where the shallow-marine facies first occur, suggests the host strata are of the Nemakit–Daldynian age. Although the base of the Nemakit–Daldynian Stage cannot be precisely defined in the section, it putatively corresponds to the base of the Ust’-Tagul Formation.

The methodical basis, development, and current state of a new method of chronostratigraphic studies, i.e., strontium isotope stratigraphy (SIS), are considered. This method makes it possible to date and correlate geographically distant sedimentary sequences without involving the biostratigraphic and isotope geochronological data. SIS is based on secular variations in 87Sr/86Sr in the paleocean, resulting from the redistribution of the roles of two global strontium flows formed in the mantle and continental reservoirs of the Earth. Isotopic homogeneity of Sr in the paleoceans and in the linked seas leads to the fact that the 87Sr/86Sr ratio in the sea basins is individual for each geological time point and is inherited in marine chemogenic sediments under deposition of dissolved Sr as an isomorphic impurity. Low-Mg calcite and also fragments of fossilized paleontological remains buried in situ are the best minerals that are capable of retaining the Sr isotopic signature of the sedimentation environment. SIS is carried out with geochemical diagnostics of secondary alteration of the studied material and selective dissolution of the samples to produce a carbonate material that adequately reflects isotopic signature of the sedimentary basin. Interregional correlations of the Proterozoic and Cenozoic sea sediments and their relation to the SIS-based stratigraphic scale are given as an example.

Dating of fungal divergences with molecular clocks thus far has yielded highly inconsistent results. The origin of fungi was estimated at between 660 million and up to 2.15 billion y ago, and the divergence of the two major lineages of higher fungi, Ascomycota and Basidiomycota, at between 390 million y and up to 1.5 billion y ago. Assuming that these inconsistencies stem from various causes, we reassessed the systematic placement of the most important fungal fossil, Paleopyrenomycites, and recalibrated internally unconstrained, published molecular clock trees by applying uniform calibration points. As a result the origin of fungi was re-estimated at between 760 million and 1.06 billion y ago and the origin of the Ascomycota at 500-650 million y ago. These dates are much more consistent than previous estimates, even if based on the same phylogenies and molecular clock trees, and they are also much better in line with the fossil record of fungi and plants and the ecological interdependence between filamentous fungi and land plants. Our results do not provide evidence to suggest the existence of ancient protolichens as an alternative to explain the ecology of early terrestrial fungi in the absence of land plants.

Macroscopic fossils as three-dimension molds and casts of Ediacara-type soft-bodied organisms were found in the Kachergat Formation of the Upper Precambrian Baikal Group of the Western Cisbaikalia for the first time. Among them, the species Palaeopascichnus delicatus and P. linearis of the group palaeopascichnida and Arumberia -type microbially induced sedimentary structures were identified. These findings significantly clarify the age limits of the deposition of the Kachergat Formation and the Baikal Group itself, the stratigraphic position of which in the Upper Precambrian section of Western Cisbaikalia has been controversial.

A new organism, Olgunia bondarenkoae gen. et sp. nov., with a level of colonial organization similar to that of sponges or coelenterates, is described from the Vendian of the southeastern White Sea region. The new genus is characterized by a modular pattern and coordinated growth of neighboring individuals arranged in a fan-shape. The characters shown in the new genus were formerly considered diagnostic of the genera Vaveliksia Fedonkin and Funisia Droser et Gehling. All three genera are therefore here combined into a new family Olgunidae, with the type genus Olgunia gen. nov. Coloniality in the Precambrian is discussed.

The complex body-trace fossils of Vendian soft-bodied biota have been found for the first time in the Central Urals during the study of the Vilukha and Sinii Kamen members of the Chernyi Kamen Formation of the Upper Vendian Sylvitsa Group (Kos’va River area, Perm Krai of Russia). These sedimentary sequences were exposed along the valley of the Shirokovskii Reservoir. Among the fossils, the chuariomorpha-like species Beltanelliformis konovalovi , previously described from the Konovalovka Member of the Chernyi Kamen Formation, was identified. However, the morphological analysis of the new fossil material revealed a number of principal differences from representatives of the genus Beltanelliformi s Menner, 1974. It was shown that the taxon B. konovalovi , most likely, does not belong to this genus and probably needs further revision, and, in turn, the fossil locality at the Shirokovskii Reservoir allows us to establish a new area with fossils of the Precambrian mobile organisms.

Data on the first appearances of major animal groups with mineralized skeletons on the Siberian Platform and worldwide are revised and summarized herein with references to an improved carbon isotope stratigraphy and radiometric dating in order to reconstruct the Cambrian radiation (popularly known as the ‘Cambrian explosion’) with a higher precision and provide a basis for the definition of Cambrian Stages 2 to 4. The Lophotrochozoa and, probably, Chaetognatha were first among protostomians to achieve biomineralization during the Terreneuvian Epoch, mainly the Fortunian Age. Fast evolutionary radiation within the Lophotrochozoa was followed by radiation of the sclerotized and biomineralized Ecdysozoa during Stage 3. The first mineralized skeletons of the Deuterostomia, represented by echinoderms, appeared in the middle of Cambrian Stage 3. The fossil record of sponges and cnidarians suggests that they acquired biomineralized skeletons in the late Neoproterozoic, but diversification of both definite sponges and cnidarians was in parallel to that of bilaterians. The distribution of calcium carbonate skeletal mineralogies from the upper Ediacaran to lower Cambrian reflects fluctuations in the global ocean chemistry and shows that the Cambrian radiation occurred mainly during a time of aragonite and high-magnesium calcite seas.