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Consideration is given to the nature of mafic–ultramafic bodies in the southeastern part of the Aldan-Stanovoi Shield using the Kun-Manie ore field as an example. These bodies played an important role in the formation of the Kun-Manie sulfide copper–nickel deposit as conduits of sulfide-bearing magmas. A detailed mineralogical and geochemical study with interval sampling was carried out on core samples from the drilling of two intrusive bodies, Treugolnik and Iken, using drill holes 21 and 25. The drill–core data present evidence for their origin from a single parent magma. The Treugolnik and Iken minor intrusions were emplaced in magmatic chambers at different depths during the cotectic crystallization of dark minerals from the primary picrite (Treugolnik body) and intermediate picrobasalt (Iken body) magmas. A comparative study of petrogeochemical and mineralogical data suggests that the Treugolnik intrusion formed as a closed system with magma emplaced in a single, relatively rapid injection and crystallized without losses; the Iken sill formed as an open system as a result of magma emplacement in several pulses with time intervals between injections. These magma bodies, together with the host metamorphic rocks, were involved in tectonic deformations after they crystallized.

The problems of large-scale contamination of the Shufan volcanic plateau (Primorye) basalts with selective melts from xenoliths are discussed. Silico-alkaline liquids that are selectively extracted from xenoliths mix only to a limited extent with the basalt melt, and form granophyre bands that give lavas a taxitic texture. The unique compositions of buchites (pelitic xenoliths chemically modified with a diffusion interaction with basaltic magma and selectively molten politic xenoliths) are characterized. The mineral associations of buchites are represented by highly ferriferous cordierite (sekaninaite), ultra-ferriferous hercynite, (Al, Zr) Fe-armalcolite, Zr-ilmenite, mullite, sillimanite, high-lanthanum monazite, and a barium–phosphate–aluminosilicate phase. The features of the chemical and mineral composition of buchites reflect the accumulation of refractory elements (Al, Fe, Ti, Zr, Ni, and Cr) in the restitic material of xenoliths, followed by the formation of ultra-aluminous, ultra-ferriferous, and initially immiscible metal-silicate composition. Low Pb isotopic ratios in the Shufan basalts indicate selective contamination with material of the ancient cratonic basement. A steady increase in these values is observed for basalts contaminated with the upper crustal material, which also reflects the isotopic composition of buchites.

The mineral and chemical compositions of the layered subvolcanic ultrabasic rocks formed through fluid–silicate (liquid) separation of the ultrabasic magma into high-potassium and low-potassium fractions are characterized by the example of the layered picritic sill from the Late Cretaceous ultrabasic volcanic complex of Eastern Kamchatka. It is determined that the main potassium concentrator in the picrites from the high-potassium layers is a residual volcanic glass containing up to 8–9 wt % K2O, which is unique for ultrabasic melts.

The Kirganik copper–porphyry deposit is situated in the central part of the Sredinnyi Mountain Range of Kamchatka and is confined to fields of development of potassic orthoclase metasomatite and hypabyssal intrusions of shonkinite. Platinum group metals (PGMs), such as merenskyite, kotulskite, keithconnite, and temagamite, were discovered in the chalcopyrite–bornite and chalcopyrite–bornite–chalcosine ore of the deposit for the first time.

The problem of the geochemical classification of granitoid magmatism in the zone of interaction of oceanic and continental plates is considered in this paper by the example of Mesozoic granitoids of the Krutogorova and Kol’ intrusive complexes of the Sredinny Range, Kamchatka. Based on new geological, petrological, and geochemical data (including the Sr, Nd, and Pb isotope systematics of rocks), it was shown that the protoliths of the granitoids were volcanic-terrigenous sequences accumulated within a Cretaceous marginal basin in the eastern Asian continent. The granitoids crystallized at ∼80 Ma (SHRIMP U-Pb age) under the conditions of the andalusite-sillimanite depth facies corresponding to a pressure of approximately 2 kbar and induced contact metamorphism in the host sequences, which are made up of sediments with sheetlike bodies of mafic and ultramafic volcanics (Kikhchik Group and its metamorphic analogues of the Kolpakova, Kamchatka, and Malki groups). The lower age boundary of sedimentation of the host sequences and the time of basic volcanism coincide with the beginning of the formation of the Okhotsk-Chukotka volcanic belt. Such a correlation is not accidental and reflects a genetic connection between the processes of magmatic activation in the continental-margin sedimentary basin and the formation of the continental margin volcanic belt in eastern Asia. The development of basic volcanism in the sedimentary basin accompanied by the ascent of deep fluids resulted in the entrainment of crustal materials into magmatic processes and the formation of crustal magma chambers, the activity of which was manifested by the eruption of intermediate and silicic lavas and emplacement of shallow granitoid intrusions of considerable areal extent. These intrusions induced contact metamorphism in the enclosing volcanosedimentary complexes. The subsequent Eocene (60-50 Ma) collision processes related to the obduction of the oceanic segment of the crust of the transitional zone onto the Asian continental margin resulted in the tectonic piling of the rocks of Central Kamchatka and strong crustal thickening, which was favorable for its metamorphic alteration reaching the kyanite-sillimanite depth level of the amphibolite facies under the influence of a thermal front and deep fluids affecting lower crustal zones. The Eocene regional metamorphism caused not only metamorphic transformations, migmatization, and granitization in the sequences of the Sredinny Range, which underwent only contact hornfels formation during the first stage, but also metamorphism, migmatization, and extensive foliation in the igneous rocks of the Kol’ and Krutogorova complexes, which were transformed into gneissic metagranites.

Metabasites (amphibolites, garnet amphibolites, and basic crystalline schists) compose numerous sheeted bodies (often highly boudined) from a few to 100 meters thick in the plagiogneisses and migmatites of the Kolpakov Group. Chemically, they are reconstructed as basalts and picrites that were metamorphosed, as host terrigenous rocks, under the kyanite-sillimanite subfacies of the amphibolite facies (t = 620–650°C, P s = 5.9–6.9 kbar). Metabasites are dominated by amphibolites and basic crystalline schists distributed throughout the entire section of the Kolpakov Group, whereas garnet amphibolites are more typical of the upper parts of the group, where they are intercalated with amphibolites, basic crystalline schists, plagiogneisses, and quartzites. Metaultrabasites (plagioclase-free amphibolites) occur much more rarely as small boudins up to few meters in size. According to U-Pb SHRIMP zircon dating, the plagiogneiss protolith age corresponds to the end of the Early-Late Cretaceous (90–100 Ma), which is similar in age to the weakly metamorphosed terrigenous deposits of the Kikhchik Group of the Sredinny Range. This allows us to consider the terrigenous rocks of these groups as isofacial sedimentary rocks. The same age (Early-Late Cretaceous boundary) was taken for protoliths of metabasites forming interbeds among metaterrigenous deposits of the Kolpakov Group. The interval of 100−90 Ma coincides with the beginning of the formation of the Okhotsk-Chukotka volcanogenic marginal-continental belt in East Asia. It is shown that the Kolpakov Group possesses the geochemical features of tholeiitic basalts of different geodynamic settings and comprises both typically island arc (low-Ti) and oceanic (moderate to high-Ti) tholeiites associated with ultrabasic volcanic rocks—picrites. Such a chemical peculiarity of basic rocks is typical of the marginal-continental extension zones (pull-apart basin) that were initiated on the sialic crust. It is obvious that similar geodynamic setting of the basite magmatism existed for the Sredinny Range of Kamchatka. The ascent of the mantle matter beneath the extension zone of the continental crust of the sedimentary basin and its intersection by faults that formed simultaneously with the Okhotsk-Chukotka volcanogenic belt served as the beginning of the basite volcanism in the sedimentary basin. They provided an intense fluid effect and a temperature increase in the crust with subsequent granitization and metamorphism of volcanogenic-terrigenous deposits and, finally, the development of the modern structure of the Sredinny Kamchatka Massif. The intense Late Cretaceous basite volcanism and associated granitoid magmatism in Kamchatka were presumably caused by the ascent of mantle plumes bearing hydrogen fluids.

The metavolcanic rocks of the Kvakhona Formation exposed on the western slopes of the Sredinnyi Range metamorphic massif are represented by two sequences. The lower sequence occupying the most part of the exposed formation is dominated by porphyric and aphyric clinopyroxene-plagioclase metabasalts and their tuffs with subordinate metapicritic basalts, metaandesites and their tuffs, and metadacites. The latter form isolated bodies in the northern part of the Kvakhona exposures. The upper sequence is composed of metaandesites, metabasalts, and their tuffs intercalated with terrigenous rocks (siltstones, sandstones, and carbonate graywacke) and metadacite bodies. The rocks were subjected to intense metamorphism under the greenschist facies conditions (t = 250–420°C, P s around 1 kbar) with the replacement of clinopyroxene phenocrysts (or their clasts in the tuff varieties) by actinolite, chlorite, and epidote, while plagioclase phenocrysts are replaced by albite, muscovite, chlorite, and epidote. In the metabasalts enriched in ore minerals, clinopyroxene is replaced by very thin veinlets and the finest grains (about 20–30 μm) of Ca-Na and Na amphiboles (winchite, ferrowinchite, glaucophane, and ferroglaucophane). The groundmass of the rocks (or tuff cement) consists of variable combinations of titanite, magnetite, chlorite, epidote, silpnomelane, and albite. The metabasalts of the formation belong to the high-Fe and often high-Ti rocks, which makes them similar to the tholeiitic basalts of mid-ocean ridges or rifting zones. The metaandesites and metadacites also preserved an elevated Fe content and belong to calc-alkaline series rocks typical of island arcs and active continental margins. It is suggested that the primary rocks of the Kvakhona Formation were formed within volcanic centers on the floor of a vast Cretaceous epicontinental marginal basin, which accumulated thick sequences of terrigenous rocks. The detrital material for these rocks was supplied from the northeastern Asian continent. The geological and geochemical data testify to the similarity of the Kvakhona metavolcanic rocks and the greenstone altered volcanic rocks of the Pensantain Range of Western Kamchatka, which are dated by the U-Pb SHRIMP method at 90–100 Ma. The protolith of the metavolcanic rocks of the Kvakhona Formation was presumably formed within the same age interval.

The Dukuk intrusive massif is considered as petrotype of the Ni-bearing gabbro-norite-cortlandite complex of Kamchatka. This paper advances a new concept of the structure of the Dukuk Massif and relations between its gabbroid and ultrabasic rocks. The study of the trace element distribution sheds light on the origin of the parental melt of the norite-cortlandite complex and on the prospects for the discovery of economic sulfide mineralization in it. New U-Pb data on the Dukuk intrusion specified the age of this massif and the entire complex.

Chances for estimating the FeO/Fe2O 3 tot ratio in rocks by the K and L series of X-ray fluorescence spectra are studied. The errors in the determination of FeO/Fe2O 3 tot by the intensity ratio of the Kβ2,5/Kβ1,3 and Lβ/Lα1,2 lines are compared. The relative standard deviation of determining FeO using a set of 49 standard samples of eruptive rocks varies in the range 5–16%, depending on the ratio FeO/Fe2O 3 tot and the concentration of FeO. The better precision is attainable for a ratio above 0.45 at a FeO concentration in the range 5–15%. For samples of andesites and basalts, the relative standard deviation is better than 4%, for rocks of the granite family it is 23% at FeO concentrations below 3%. For samples of metamorphic and sedimentary rocks, the error of FeO determination is higher than that for the eruptive ones. For samples with the ratio FeO/Fe/Fe2O 3 tot < 0.25, the deviation may exceed 30 rel %. In contrast to chemical analysis, the X-ray fluorescence method appears advantageous in time and cost of sample preparation and can be used for routine analysis in geochemical research.

It is shown that formation of high-temperature granulite-like rocks in the contact aureole of the Yurchik gabbronorite intrusion of the Ganal Ridge in East Kamchatka was caused by contact metamorphism, metasomatism, and local melting of the primary sedimentary-volcanogenic rocks of the Vakhtalkinskaya Sequence of the Ganal Group. The temperature in the inner part of the aureole reached 700–800°C and caused transformation of basic rocks into two-pyroxene-plagioclase, clinopyroxene-amphibole-plagioclase, and amphibole-plagioclase rocks, while sedimentary rocks were replaced by garnet-biotite and garnet-cordierite-biotite hornfelses. Locally, basic volcanic hornfelses were subjected to metasomatic alteration with the formation of bodies of biotite-orthopyroxene-plagioclase metasomatites. In the zones of the most intense fluid filtration, the metasomatites experienced local magmatic replacement resulting in the formation of biotite-orthopyroxene-plagioclase ± garnet migmatite veinlets and patches. Bodies of garnet enderbites were formed after sedimentary interlayers at temperatures of 700–800°C and a lithostatic pressure of 3.2–4.8 kbar. The comparison of the chemical composition of the Vakhtalkinskaya basic volcanics and the products of their transformation indicates that, in terms of chemistry, the metasomatic alterations and magmatic replacement correspond to siliceous-alkaline metasomatism (granitization) causing a subsequent and uneven influx of Si, Al, Na, K, Rb, Ba, Zr, Nb, and Cl and removal of Fe, Mg, Mn, Ca, and some trace elements (Cr, Co, Ti, Y, and S). The processes of metamorphism and metasomatism were presumably provoked by highly mineralized mantle fluids that were filtered through magmatic channels that served as pathways for gabbroid magma.

Geological-petrological data were first obtained on the Early Miocene basaltoids and spinel-fassaite carbonatite tuffs of the Ambinsky volcanic structure in southwestern Primorye. The geological study of Ambinsky volcano allowed the reconstruction of stratigraphic sections across lava and pyroclastic basaltic rocks and stratified carbonatite tuffs. The chemical compositions of rocks and mineral phenocrysts from basalts and carbonatite tuffs are reported. The basaltoids are classed with undifferentiated moderately alkaline within-plate basalts. Evidence of carbonate-silicate immiscibility was found in the basaltoids and carbonatite tuffs. It was suggested that the formation of the carbonatite melt associated with simultaneous basification and abundant crystallization of spinel, fassaite, as well as oversaturation of the silicate system in Ca was caused by limestone assimilation, subsequent transformation of the melt, and liquid immiscibility. Thermal decomposition of carbonates with dissolution of released CaO in magma and accumulation of CO2 in a closed magmatic chamber gave rise to the autoclave gas effect and, correspondingly, heavy explosive eruptions atypical of such volcanic rocks. The genesis of carbonatite tuffs of Ambinsky volcano can serve as a model example of exsolution of carbonate melt in the moderately alkaline nonagpaitic basaltic system.

This paper reports specific mineralogical and geochemical characteristics of deposits from the local depressions of the Derugin Basin. They were formed in an environment with periodic changes from oxic to anoxic conditions and show evidence for the presence of hydrogen sulfide in bottom waters. The deposits of this type can be considered as a modern model for ancient ore-bearing black shale associations. Compared with typical metalliferous black shale sequences, which are characterized by high contents of organic matter, the sediments described here are depleted in the elements of the organophilic association (Mo, Ni, Cu, Zn, V, and U) but have higher Mn contents.

The geology and mineralogy of host metamorphic rocks, the mineralogy of sulfide ores, and the distribution of PGE mineralization were studied in detail for the Kvinum-1 and Kvinum-2 copper-nickel occurrences of the Kvinum ore field, which are the most promising targets for the copper-nickel-PGE mineralization of the Sredinny Range of Kamchatka. It was established that stringer-disseminated and massive copper-nickel ores are localized in amphibole peridotites, cortlandites, and form ore bodies varying from tens of centimeters to 5–20 m thick among the layered cortlandite-gabbroid massifs. The massive sulfide ores were found only at the bottom of cortlandite bodies and upsection grade into stringer-disseminated and disseminated ores. Pyrrhotite, chalcopyrite, and pentlandite are the major ore minerals with a sharply subordinate amount of pyrite, sphalerite, galena, arsenopyrite, and lollingite. Besides pentlandite, the Ni-bearing minerals include sulforasenides (gersdorffite), arsenides (nickeline), and tellurides (melonite) of nickel. It was found that PGE mineralization represented by antimonides (sudburyite) and tellurobismuthides (michenerite) of Pd with sharply subordinate platinum arsenide (sperrylite) is confined to the apical parts of massive sulfide zones and the transition zone to the stringer-disseminated ores. Ore intervals enriched in arsenides and tellurides of Ni, Pd, and Bi contain high-purity gold. In the central parts of the orebodies, the contents of PGE and native gold are insignificant. It is suggested that the contents of major sulfide minerals and the productivity of PGE mineralization in the cortlandites are defined by combined differentiation and sulfurization of ultramafic derivatives under the effect of fluids, which are accumulated at the crystallization front and cause layering of parental magmas with different sulfur contents. The fluid-assisted layering of mafic-ultramafic massifs resulted in the contrasting distribution of PGM in response to uneven distribution of sulfur (as well as As, Te, and Bi) during liquid immiscibility. The productivity of PGE mineralization significantly increases with increasing contents of S, As, Te, and Bi (elements to which Pt and, especially, Pd have high affinity) in fluids.