The meteoritic-material-normalized REE patterns of rare-metal granite intrusions of the ore-bearing Kukul’bei complex (J2–J3), eastern Transbaikalia, were studied. It is shown that the intrusions were initially enriched in granitophile volatiles and trace elements (rare metals), i.e., this phenomenon is not related to the differentiation of their parental magma chambers. On the differentiation of the Kukul’bei rare-metal intrusions, the REE contents decrease in passing from granites of the main intrusive phase (MP) to late leucocratic differentiates (muscovite and amazonite granites), the differentiates become more enriched in granitophile elements, and their rare-metal contents drastically increase as compared with the MP granites. The ore-bearing bodies of muscovite and amazonite granites have extremely low REE contents and the highest contents of granitophile (including ore-forming) elements. The REE patterns of the Kukul’bei intrusive differentiates are not universal among rare-metal intrusions. By the example of highly ore-bearing rare-metal granite intrusions of the Erzgebirge, Central Europe, it has been established that their late deep-seated differentiates (ultrarare-metal lithionite-zinnwaldite Li-F-granites) accompanied by highly productive Sn-W mineralization concentrate both granitophile elements and REE (particularly HREE). Among the studied Transbaikalian rare-metal intrusions of the Kukul’bei complex, only the differentiates of the most ore-bearing Sherlovaya Gora intrusive system belong to the above type. The analysis of the REE patterns of the Kukul’bei granites confirmed the earlier conclusions on the low ore potential of the rare-metal mineralization of the studied intrusive complex.

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The distribution of gold in rocks from some igneous complexes of the central and southwestern areas of eastern Transbaikalia (Daurian, Aga, and Argun structure-formational zones) was studied by quantitative extraction–atomic-absorption analysis and mass spectrometry with inductively coupled plasma (Element-2 mass spectrometer). High gold concentrations (on average, 0.0043 ppm) are typical of the most widespread hornblende-biotite granodiorites and granites of the main phases of batholith intrusions in the Upper Paleozoic Unda complex in the east of the study area and in the Triassic–Middle Jurassic Kyra complex in the west. The rocks of the Early–Middle Jurassic (Sokhondo) and Middle–Upper Jurassic (Shakhtama, Kharalga, and Kukul’bei) complexes have much lower Au concentrations (mainly 0.0014–0.0030 ppm), with the minimum ones established in the Shakhtama complex. During the magmatic differentiation of granitoid intrusions, the concentrations of gold in the late leucogranite differentiates decreased. The Au concentrations in the studied complexes do not depend on the composition of the host terrigenous rocks of different ages, which evidences the endogenous nature of the revealed differences in Au concentrations in the regional granitoids. Abnormally high concentrations of gold in some studied samples are observed mainly in the regional hydrothermal mineralization occurrences. The classification R-type cluster analysis showed that all variables of the studied igneous rocks are subdivided into three groups by the degree of correlation. Gold shows a distinct tendency to the correlation with siderophile oxy- and sulfurophile groups of metals. The Q-type analysis generally confirmed the correctness of the known formational classification of the regional granitoids.

The paper gives major-element and extended trace-element descriptions of plutons from the Shakhtama complex in the Aga tectonic zone (Transbaikalia). They are composed of hornblende–biotite gabbrodiorites, monzonites, diorites, and granodiorites. It has been found that they were initially enriched in granitophile (including ore-forming) trace elements. This suggests consanguinity between the intrusions of the Shakhtama complex (J2–J3) and the ore-bearing Kukul’bei rare-metal complex of granites and leucogranites (J3) (Aga zone, Transbaikalia). Since granitophile elements are incompatible, their content in granitoids with an elevated mafic content from the Shakhtama complex is substantially less above the clarke than that in the rare-metal granites and leucogranites from the Kukul’bei complex, which ended postcollisional magmatism in the Aga zone. Analysis of normalized REE patterns for the granitoids from both complexes has revealed their magmatic heterogeneity. It has been demonstrated that the Kukul’bei granite and leucogranite intrusions in the western Aga zone are granitic differentiates of granitoid magma chambers associated with the Shakhtama complex, which were initially enriched in granitophile trace elements. The granites from the rare-metal intrusions of the Kukul’bei complex (in the eastern periphery of the Aga zone) are not directly related to the magma chambers of the Shakhtama complex. They are magmatic melts, which might result from the deep-level selective melting of metamorphosed rocks enriched in volatile trace elements. It has been confirmed that there is no direct genetic relation between the majorand trace-element compositions of the granitoids and their metallogeny and ore content. The granitophile rare-metal specialization of the intrusions in Mesozoic Transbaikalian gabbrodiorite–monzonite–granodiorite and leucogranite complexes is the major evidence supporting the theory of the formation of late- and postcollisional magma chambers associated with deep faults, which were initially enriched in volatile and incompatible trace elements.

Analysis of the genetic relationship of Sn-bearing granitoids with ultrapotassic basic magmatism showed that their metallogeny was determined by the geochemistry of a specific reservoir localized in the continental lithosphere mantle (metasomatized mantle). The granitoid formation is well explained by the binary model of mixing of primary melts (products of the metasomatized mantle) with the continental crustal material. Geochemical studies of basic magmatism of different ages showed that the specific lithosphere reservoir formed in the Middle-Late Jurassic and existed at least till the late Late Cretaceous, i.e., during both tin metallogenic epochs of the Chukchi region.