L. P. Plyusnina, G. G. Likhoidov, J. A. Shcheka, I. I. Fatyanov
Physico-chemical conditions of propylite and pyroxene skarn formation of the Mnogovershinnoye deposit (Lower Priamurye

Based on the composition of natural mineral associations (mainly propylites) of the Mnogovershinnoe gold deposit, hydrolysis reactions with epidote and/or hedenbergite, albite and other minerals have been studied. The selected mineral associations are determined through interaction with a fluid governing gold behavior in the course of deposit formation. Solubility of gold in the model fluid was measured at 300 and 400°C (Ptot = 1 kb) with the selected solid buffers involved. The hydrothermal medium was modeled by 1m NaCl solutions of different acidity. Some physico-chemical parameters were simulated by Gibbs free energy minimization method using the "Selector-C" and "Gibbs" software packages. As a result, the buffering capacity of the studied associations was ascertained, and the values of pH, O₂ fugacity were calculated in the studied P-T range. The measured gold solubility increases with temperature (lgmAu): from -7.54 to -7.26, and to –6.69 at temperatures over 360°C due to spontaneous formation of hedenbergite, initiating pH increase in the medium. It is concluded that propylites present an effective geochemical barrier on which gold deposition occurs when the total Au content in a hydrothermal fluid exceeds (mg/L) 0.004 and 0.011 at 300 and 400°C (1 kb), respectively. Similarly, with hedenbergite present, the values rise to 0.02 and 0.06, respectively.

 A.V. Tatarinov, L.I. Yalovik, G.A. Yalovik
Gold mineralization in thrust structures of the Mongol-Okhotsk collisional suture (Pre-Shilka and Onon-Turin zones

Thrust structures play the leading role in localization of gold mineralization (Kariyskoye, Pilnenskoye, Pogromnoye, Ilynskoye deposits, etc.), which occur in the Pre-Shilka and Onon-Turin zones. Most of the ore bodies are concentrated in rocks of the dynamometamorphic complex of thrust structures of various morphogenetic types, i.e. zones of autoclastic, polymictic and serpentinite melange, lozange, mylonite junctures of multi- and monojuncture thrusts.
The thrust structures are promising for search for large deposits characterized by great gold reserves as compared with insignificant gold content in the ores.

S.M. Sinitsa
The origin of the gneissic facies of Sergeevskiy gabbroides (Southern Primorye

New evidence is to conclude that Sergeevskiy gabbro-gneisses or gabbro-amphibolites formed as such rather during pluton formation than after it, under the influence of superimposed processes.

G.A. Valuy
Petrologic features of granitoids of the East Sikhote-Alin volcanic belt

Granitoids of the southern part of the East Sikhote-Alin volcanic belt form three groups of bodies crystallized at a small (< 3-4 km) depth, separated in space and differing in their petrologic features. Intrusive bodies of the eastern part (the Japanese Sea coast - group 1) form large (tens of kilometers) multiphase bodies composed of equigranular rocks of diorite-granodiorite-granite composition, which crystallized at 650-750°C. They are the derivates of the I-type melts, and belong to the magnetite series.
The massifs of the western part of the belt are located within the Dalnegorsk district (group 2) and the Krasnorechensky Rise (group 3); they are monophase formations composed of distinctly porphyry-like rocks of granodiorite-monzodiorite composition. They belong to the ilmenite series, and are the derivates of the S-type melts. They crystallized at 750-800°C and 850-900°C, respectively, and form small bodies (the first kilometers in the Dalnegorsk district, and tens of kilometers in the Krasnorechensky Rise). They are accompanied by borosilicate and polymetallic deposits in the Dalnegorsk district, and by tin-polymetallic deposits in the Krasnorechensky Rise, whereas in the intrusive bodies of the coastal group, minor magnetite-skarn and molybdenum manifestations are known.

 Chen Shuwang, Jinchengzhu, Zhangyunping, Zhang Lidong, Guo Shengzhe
Discussion on the Structural-Volcanic Activities and Biological Events During the Early Cretaceous in the Sihetun Area, Liaoning Province, China

The Sihetun area is situated in a Mesozoic volcanic-sedimentary basin. The main structures of the Early Cretaceous in the area are NE and NW faults, which control not only the major boundaries of the basins, but also some volcanic edifices. Based on the field mapping, the Yixian Formation, which is the only strata of the Early Cretaceous in the area, may be subdivided into three members: The first member is basic and intermediate-basic volcanic rocks with intercalations of tuffite beds. The second member is mainly sedimentary beds of lacustrine facies with intercalations of crystal tuff, tuffite and some pillow lavas. And the third member is mainly basalt. The Jehol Biota (including gastropods, bivalves, conchostracans, ostracods, insects, fishes, amphibians, reptiles, birds, mammals, as well as fossil plants) occurs mainly in tuffite beds of the first member; and muddy shale beds are related to the second member of the Yixian Formation. Excavation and trace element analysis indicates: Jehol biota experienced mass mortality and rapid burial; toxic gases of volcanic activities are the main factors of the biological catastrophic event. According to isotopic dating, the Yixian Formation is Early Cretaceous in age. By comprehensive studies, six evolutionary stages (from A to F) of the structural-volcanic activities and biological events during the Early Cretaceous in the Sihetun area are also discussed. Stage A is “the formation of the embryonic basin and the early members of Jehol biota”; Stage B is “the first volcanic activity and biological hazard”; Stage C is “the dormant volcanic activity and the development of Jehol biota”; Stage D is “the volcanic exhalation and the catastrophe of Jehol biota”; Stage E is “tuff sediment”; and Stage F is “the end”, respectively.

А.М. Korotkiy
Eocene-Pleistocene deposits of the river terraces of Southern Primorye

On the basis of complex analyses (sporo-pollen and diatom analysis, paleomagnetic and termoluminescence analyses) of deposits of the Khasanskaya (mouth of Tumannaya River), Perevoznenskaya (Amur Bay), and Telyakovskaya high terraces (Ussuri Bay), the deposits of Eo-Pleistocene (eQ) have been distinguished and divided into two links. The lower link is suggested to comprise the stratigraphic subdivisions: the Telyakovskiy (termochrone– eQ¹tl) and the Tumanganskiy (cryochron - eQ²tm) horizon; and in the upper link, the Talminskiy (termochrone – eQ_II¹tlm) and Perevoznenskiy (cryochron – eQ_II²prs) horizons have been discriminated. For each distinguished horizon, the features of spore-and-pollen assemblages and their conformity to paleolandscapes have been determined. The directional disappearance from the fossil composition of exotic forms, characteristic of Neogene deposits, has been established for the pollen and diatom assemblages. Apart from the referred stratotype sections, the distribution of Eo-Pleistocene deposits in the fluvial valleys of the Sikhote-Alin (Kishinevskaya and Misusinskaya terraces) has been established in the territory of Southern Primorye.

A.A. Svitoch
Marine Pleistocene of the Russian Far Eastern coasts (stratigraphy and paleogeography

Stratigraphical subdivision of marine Pleistocene deposits of the Russian Far Eastern coasts is described, and paleoenvironmental conditions are reconstructed. Marine Pleistocene beds differ in stratigraphical range, paleontological findings, and spatial distribution, thus considerably hampering their correlation and stratification. In the most complete sections of Chukotka and Eastern Kamchatka, fossiliferous marine deposits occur throughout the whole Quaternary sequence. Stratified marine deposits are also present on the coasts of the Kuril Islands (Golovnin Suite) and Sakhalin (Ust-Bachinsk Suite). On the coasts of the Sea of Okhotsk, especially of western Kamchatka and Primorye, reliable marine deposits are represented only by Holocene beds, while the origin of the older ones is primarily established on the basis of geomorphological criteria. Among facially diverse marine deposits, sediments of dynamically active coasts and also transitional ones (lagoonal, deltaic, etc.) are the most widely distributed. Glacial marine beds occur on the Bering Sea coasts. Paleoenvironmental conditions of the coastal areas during the Pleistocene epoch were diverse due to considerable meridional extent of the Russian Pacific coasts and complicated geological structure and evolution of the continental margin. In the marginal Far Eastern seas, transgressive-regressive cyclicity was governed by glacial eustatic sea-level oscillations, although glacial isostasy, tectonic movements, and volcanic activity were also locally important.

S.G. Kislyakov, L.P. Eikhvald
New evidence of the age of the Korelskaya and Lamskaya suites, Western Priokhotye

New evidence of the composition, geographic distribution, faunal remains, and age of the Korelskaya and Lamskaya suites and Prokhotyeis offered. The conodonts detected for the first time suggest Late Devonian age of the Korelskaya suite and Early Carboniferous age of the Lamskaya suite.

D.A. Lopatina
Vegetation and climate of the Eocene-Miocene, Eastern Sikhote-Alin (from paleobotanical analysis data

Based on the complex study of plant imprints and palynological assemblages from seven localities of the Pribrezhnyi basalt belt, Eastern Sikhote-Alin, a reconstruction was made of vegetation and climate for the late Middle Eocene – Late Miocene. The method of analogy (comparing vegetation groups with modern forests), ecological-floristic analysis, and the method of climatogramms were used. The climate at the end of the Middle Eocene–Early Oligocene (Sonye, Bui and Svetlovodnaya floras) was warm-temperate, close to subtropical. The vegetation cover was characterized by domination of broad-leaved and evergreen genera with substantial admixture of Pinaceae and Taxodiaceae. Warm-temperate climate is reconstructed for the end of the Late Oligocene–beginning of the Early Miocene (Amgu flora). Coniferous forests dominated. Flora-bearing deposits of Dembi and Velikaya Kema can be referred to the late Early Miocene – the earliest Middle Miocene (the Miocene climatic optimum). The mixed deciduous broad-leaved forests with prevailing Fagaceae, Juglandaceae, Taxodiaceae and various evergreen genera grew. The climate of the latest Middle Miocene – Late Miocene (Botchi flora) was warm-temperate, but cooler than that of the Late Oligocene –Early Miocene.