The paper presents a review of stratigraphy, lithology and metallogeny of the Paleogene and Neogene coal basins from the Primorye region of southeast Russia. The stratigraphic division of the studied sections is based on the abundant fossil plant material, represented by leaf impressions and, in lesser amounts, fruit and seed fossils, as well as detailed palynological analyses. Previously published UPb zircon and KAr bulk-rock dates of volcanic and volcaniclastic rocks were also used. As a result of this study, five stages of Cenozoic sedimentation are distinguished, namely the Late Paleocene, Early Eocene, Late Eocene, Late Oligocene, and Early Miocene. The Early Eocene, Late Eocene, Late Oligocene coal-bearing units carry high concentrations of critical elements and include 3 of the 7 most germanium-enriched coal deposits in the world. In addition, coals in the Pushkino, Pavlovka, Vanchin, Rakovka, and Rettikhovka basins contain numerous occurrences of rare earth elements and yttrium; gold occurs in the Pavlovka, Vanchin, Rakovka, Krylovka, Sredne-Bikin, and Verkhne-Bikin basins; uranium occurs in the Pavlovka, Rakovka, Rettikhovka, and Glukhovka basins; while zirconium and niobium occur in the Pushkino basin.

The paper is based on stable isotopic analyses (C, O, H) first obtained for the rare earth elements + yttrium mineralization of South Primorye and Southwest Japan in addition to recent exploration data and some K-Ar and U-Pb datings. The analyzed minerals include hydrous carbonates and clay minerals that are hosted by argillized (weathered) shale, granite, mafic rocks, and semi-lithifled sediments of various (from Cambrian to Late Cenozoic) age. The data distinctly evidence that a major agent of rare metal leaching from the host rocks and their redistribution inside the lignite-bearing sediments and weathered crust was meteoric water. Its moderately acidic character was due to carbon dioxide flowing up from the mantle through faults associated with the lignite basins, in addition to organic matter and sulfides disseminated in the host rocks. Concentrated precipitation and sorption of rare earths and yttrium from the evolved meteoric water were probably caused by their neutralization or even alkalization that had resulted from CO2 release near the surface. The previous Sr-Nd isotopic data for lanthanite-(Nd) from South Primorye indicate the upper Earth's crust origin of the ore metals. Thus, both endo- and exogenous factors significantly influenced the studied mineralization in Primorye. Juvenile CO2 made a key contribution to meteoric waters allowing them to mobilize and redistribute ore components in the near surface conditions. The deep-seated faults cross-cutting and bordering the lignite basins and providing the necessary conduits for the upflows of carbon dioxide are suggested to control localization of the studied mineralization.

This study combines our own new and literature data on oxygen isotopic compositions of corundum from the Russian territory including deposits in Karelia, Ural, Baikal and Far East regions. Corundum and associated minerals from placer and lode deposits are discussed in this review. The oxygen isotopic compositions of the colored corundum commonly result from mixing of meteoric (including glacial), crustal (metamorphic–metasomatic), and mantle magmatic waters. The individual values closely match the oxygen isotopic values in the host rocks. This allows identification of the sources for placer corundum using the δ18O value as an important component for accurate diagnostics of the gemstones. Some corundum, especially from northwestern Karelia, has extreme isotopic characteristics (δ18O down to −26.3‰), which almost invariably indicate its source location.

This paper reports the geochemical characteristics of PGE- and Au-bearing carbonaceous shales of the Sutyr and Kimkan sequences from the eastern Bureya Massif in the Russian Far East. The weakly altered shales are chemically close to the average upper crustal shale (NASC) but differ in the lower contents of iron, manganese, magnesium, phosphorus, calcium, and REE. According to the discrminant diagrams, these sediments are similar to the modern sediments accumulated under the influence of the continental terrigenous runoff, suprasubduction volcanism, and seawaters, which suggest their relation either with the deep-water trench near the active continental margin or with the central part of the marginal sea. The iron-rich sedimentary rocks of the Kimkan Sequence, including the Kimkan iron ore, are characterized by a positive Eu anomaly, which probably indicates their rift origin. The superimposed hydrothermal alterations of the Sutyr Sequence, including sericitization, sulfidization, and formation of quartz veinlets, were accompanied by the removal of silica and the input of potassium, LREE, and MREE with the formation of a well expressed Eu anomaly. The rocks from the weakly altered to metalliferous sediments of the Kimkan Sequence show a decrease in alkalis and especially in potassium. The carbon isotope composition of the Sutyr shales corresponds to that of the biogenic carbon (δ13CVPDB from −20.7 to −23.7‰). The shales of the Kimkan Sequence have a heavier carbon isotope composition (δ13CVPDB from −15.6 to −19.1‰), which may indicate either partial carbon influx from an endogenous source or its formation during decarbonatization in the presence of iron.

The paper presents newly obtained data on the oxygen and hydrogen isotopic composition of minerals in corundum occurrences and their host rocks in northern Karelia. Minerals in the Khitoostrov and Varaka corundum-bearing zones have extremely low δ18O (lower than −26‰) and δ D (lower than −215‰), which suggest that the mineral-forming process involved glacial waters and that the minerals preserve the isotopic ratios of their protolith. Aluminous corundum plagioclasites were produced by high-pressure Svecofennian (1.9-1.8 Ga) metamorphism of Paleoproterozoic rocks that had been metasomatized with the involvement of meteoric waters during the Guronian glaciation epoch.

Изучен изотопный состав кислорода и водорода минералов корундовых проявлений и вмещающих минерализацию пород северной Карелии. Установлено, что минералы корундоносных зон Хитоостровского и Варацкого проявлений характеризуются экстремально низкими величинами 18O (менее –26 ) и D (менее –215 ), указывающими на участие в минералообразующем флюиде гляциальных вод и сохранение в них изотопных отношений кислорода и водорода протолита. Глиноземистые корундоносные плагиоклазиты были сформированы в результате высокобарного свекофенского (1.9–1.8 млрд лет) метаморфизма палеопротерозойских пород, метасоматизированных с участием метеорных вод в эпоху гуронского оледенения.

Some geological, petrochemical, and geochemical characteristics of carbonaceous shales as a new unconventional natural source of gold and PGE are considered by the example of the Kimkan and Sutyr’ units of the Bureya massif (southern Far East, Russia). It is shown that shales of the units belong to the terrigenous-carbonaceous and siliceous-carbonaceous formations. They accumulated in deep-water trenches, and the active continental margin was probably their main provenance. The carbonaceous terrigenous-sedimentary units and precious-metalores in them show specific petrochemical characteristics different for complexes with predominantly PGE and gold mineralization. According to these characteristics, carbonaceous complexes with high Fe contents, low total contents of alkalies, and high K/Na ratios are promising for PGE-rich ores. Gold ores are usually localized in black-shale strata with high total contents of alkalies and low K/Na. In this respect, the shales and Fe-ores of the Kimkan unit obviously contain high-PGE mineralization, while the rocks of the Sutyr’ unit can bear gold deposits. We assume that the PGE mineralization is genetically related to the formation and transformation of carbonaceous rocks. At the same time, most of gold in the carbonaceous shales is native and is not related to carbon; it is present in mineral assemblages resulted from superimposed sulfidization and silicification.

This paper presents the first results of petrochemical and geochemical studies (by the ICP-MS technique) of adakites comprising a small extrusive body in the Ilistaya River basin (West Primor’e). Based on the data of radioisotopic dating (K-Ar method), the age of adakites corresponds to the Middle Eocene (45.52 ± 1.1 Ma). In terms of the content of most microelements and the value of the Sr/Y ratio, the discussed rocks are close to Paleogene adakites from northwest China, the Kitakami massif in Japan, and the northwestern margin of North America; these rocks are attributed to gaps in the subducted plate (slab windows). Additionally, the adakites found in Primor’e significantly differ from adakite-like rocks found in Tibet formed during melting of bottoms of the superthickened continental crust. Thus, this discovery proves the hypothesis about formation of slab windows at the Paleogene stage of the region’s evolution.

The paper shows that sapphire (corundum) and hyacinth (zircon) from the Primorye placers have genetic relationships with the Late Cenozoic within-plate basalts of mantle origin. The alternative hypothesis of their derivation from the Early-Middle Cretaceous S-type granites does not fit the evidence presented here. This conclusion is based on the age determinations (less than 15 m.y., zircon SHRIMP and Fission-Track analyses) and oxygen isotope compositions (δ18O SMOW = 4–6.5 vol %) of clastic zircon and corundum from two sapphire districts of Primorye: Marevka, occurring in the Marevka and Kedrovka river basins in the north, and Shkotovo located in the area of upper Arsenievka and Steklyanukha Rivers in the south.

The isotope composition of carbon and oxygen in humus and carbonates has been studied in the Pleistocene loess and soil of the Russian Plain in order to reconstruct the paleoclimatic parameters during the time of their formation. It is established that most of the buried soils were formed upon the mean annual temperature exceeding the modern temperature by 1–2°C. The climate aridity (the portion of C4 plants in the ecosystem) varied from 0 to 25%. It is shown that the isotope composition of carbon and oxygen in the humus and carbonates may be a reliable indicator of the paleoclimate (i.e., the paleotemperature, paleoprecipitation, and aridity dynamics). An isotope procedure of culling soil samples unsuitable for paleoclimatic reconstruction is proposed.

Quaternary loess/paleosol series and cryogenic phenomena within the East European Plain, Russia, are less studied near their northern limit than at their southern extents. The multi-disciplinary study of two loess/paleosol/cryogenic sections were carried out in the Moscow and Vladimir regions of Central European Russia, not far from the glacial limits of the Middle and Late Pleistocene. Generally, loess deposition within these regions has undergone syn- to post- deposition processes as evident from the laminated character, as well as post depositional soil moisture and temperature conditions that have commonly given rise to gleyzation and cryogenic deformations. The Middle Pleistocene Dnieper loess is calcareous here, but the Upper Pleistocene loess has been leached of carbonates. Both Upper and Middle Pleistocene paleosols have strong pedogenic features allowing their genesis to be determined whereas cryogenic deformations and other post-depositional features allow for the more detailed interpretation of cold epoch processes. Given these loess characteristics, the Moscow and Vladimir loess region may be considered as a specific facies of the East European loess area.

Three key Quaternary loess/paleosol sections were examined in the Missouri Valley (Iowa), Eustis Ash Pit (Nebraska), and in the Wittsburg Quarry (Arkansas) to gain insights into the sedimentation, environment and climate change of the U.S. Midwest. Four loess units are present separated by three well-developed paleosols. Crowley's Ridge Loess (Oxygen Isotope Stage (OIS) 8) is pre-Illinoian in age, and is the oldest loess unit investigated. A well-developed paleosol, interpreted as Yarmouth Soil (OIS 7), is found in this loess in all three sections. Overlying the Yarmouth Soil is Loveland Loess (OIS 6) which has been pedogenically altered by the Sangamon Soil (OIS 5). It has luvisolic properties but a more clayey pedogenic texture than modern luvisols and has no clear eluvial horizon. The overlying Roxana Silt (OIS 4) is pedogenically altered. At Wittsburg and Missouri Valley, the Farmdale Soil (OIS 3) is developed in the Roxana Silt. Based on pedogenic features, we correlate this paleosol to that developed in the Gilman Canyon Formation at Eustis. In Missouri Valley and Eustis sections, the paleosol has chernozemic properties and therefore, the gleyic features observed at Missouri Valley are interpreted as later alterations. Overlying the Farmdale Soil is the widespread Peoria Loess (OIS 2).

Multidisciplinary studies of two key sections (parastratotypes) of the loess–soil–glacial formation (Strelitsa and Sebryakovo-Mikhailovka sections) located in the central part of the East European Plain placed the Matuyama–Brunhes reversal well below the Lower Pleistocene till. The till attributed to the Don glaciation (maximum glaciation on the East European Plain) is separated from the M/B reversal by several units, as follows: (1) a horizon of humified loam of still uncertain stratigraphic position; (2) a loess horizon, and (3) a paleosol complex (Rzhaksa). The polarity reversal is within a “transitional zone” which includes the base of the lower (Bobrov) loess and the upper portion of the underlying soil complex (Balashov). The primary constituent of remanent magnetization has been identified using two methods—demagnetization by heating and by alternating magnetic field; such a technique ensures a high degree of reliability.

The paper reports the results obtained by the detailed studying of carbonado (the first find in a gold placer in Primorie) and a collection of diamonds that was confiscated in 1937 from a poaching small digger and was kept safe at the Nezametnyi mine (near the village of Vostretsovo), which had developed this placer deposit. In the concentrate from the placer, carbonado is associated with green corundum, various ilmenite, zircon titanian amphiboles and pyroxenes, rutile, anatase, and fragments of subvolcanic biotite picrites. All of these minerals, native aluminum, and tin occur as inclusions in the diamonds. The carbonado from Primorie was determined to be practically identical to this mineral from Brazil, has a porous structure, is characterized by orange luminescence, contains inclusions of Y, Ce, La, Ba, and Sr phosphates, and has an isotopically light composition of its carbon (13C from −25 to −32‰). Pores of the carbonado aggregates contain clusters of diamond crystals. The collection of diamonds from an unknown source included six gem-quality transparent crystals, one rounded ballas, two cuboctahedral crystals (one of greenish and the other of silver-gray color, both with outer coats), and one black carbonado grain. The data obtained on the mineralogy of the diamonds have demonstrated that they are completely identical to this mineral from kimberlites and lamproites but bear traces of intense dissolution, fragmentation, multiple recrystallization, and graphitization at defects, which are the most widespread in the ballas. One of the crystals was determined to contain inclusions: aggregates of potassic omphacite (0.50 wt % K2O) and corundum. Ilmenite (containing up to 8 wt % MgO), titanaugite, kaersutite (4 wt % TiO2, 0.8 wt % K2O), and churchite (aqueous phosphate) were obtained from the core of the ballas. The titanaugite, kaersutite, and ilmenite were proven to be compositionally analogous to these minerals from picrites occurring near the placer. The carbon isotopic composition δ13C of the cores of the single diamond crystals varies from −6 to −11‰. The margins of the grains were proved to be enriched in the light carbon isotope (δ13C from −19 to −21‰). The gem-quality transparent diamond crystals are characterized by blue luminescence, and the color of luminescence in the carbonado varies from orange red in the bulk of the aggregate to yellowish green in its core. The aforementioned transformations of diamonds were likely caused by their transportation in pipes of micaceous picrites of the Jurassic meymechite complex. The carbonado are thought to correspond to the final stage of the metastable recrystallization (in pores, within the temperature range of the rutile-anatase transition) of the original isotopically heavy diamonds under the effect of various oxidizers (H2O, CO2, F, and others) and in the presence of catalytically acting REE, Ti, and P. The primary diamond source (kimberlite or lamproite) can be older and more distant from the study area. The complete geological analogy between the study area in Primorie, Kalimantan Island in Indonesia, and West Australia (where no sources of the placers are known) led us to consider the territory of Primorie as promising for exploration for diamondiferous placers.

The paper presents results of the study of assemblages of clastic heavy minerals and geochemical features of some assemblages in several Permian-Mesozoic cherty and siliceous-clayey sequences of Sikhote Alin. They are composed of pelagic and hemipelagic sediments of the Panthalassa (Paleopacific) Ocean. Four typical mineral assemblages and their environments are established. In one of the ocean segments, where sedimentary cover formed during the Late Paleozoic-Early Cretaceous, the Permian pelagic domain was characterized by the amphibole-pyroxene assemblage with heavy minerals derived from ophiolites. The Triassic-Jurassic stage was marked by development of the clinopyroxene assemblage with heavy minerals derived from intraplate alkaline volcanic complexes. Middle-Late Jurassic hemipelagic sediments host the zircon-clinopyroxene assemblage with a greater role of continental environments and the presence of volcanic products of the convergence zone. Another segment of the ocean accumulated red cherts and siliceous-clayey sediments during the Jurassic-Early Cretaceous under the influence of island-arc volcanism.