卷 60, 编号 8 (2018)

The evolution of rock-forming minerals (orthopyroxene, garnet, biotite, and amphibole) is studied in successive generations of granites and leucosomes. It is shown that the trace element partition coefficients between solid phases and melt are governed by an exponential dependence on the ionic radii (Brice, 1975), which is manifested especially clearly for REE. The influence of the composition of an anatectic melt and acidity/alkalinity of the mineral environment on the partition coefficients is high enough to erase the effect of temperature and pressure. The garnet–orthopyroxene assemblage in the melt generation zone results in accumulation of LREE and lithophile elements (Rb, Sr, and Ba), while HREE, Cr, and V are retained in the residue together with Cr and V. HFS elements (Nb, Zr) can accumulate in granitoid melts. In contrast, an amphibole-bearing residue causes the melt to be depleted in REE, Y, Nb, and enriched in Rb, Sr, Ba, and Zr. Special attention is given to the behavior of Nb, Cr, V, and Ti in biotite. Their D_i is always significantly greater than unity. The migmatite leucosome is often enriched in biotite, which causes the melt to be depleted in these elements. A similar behavior is also found for lithophile elements (Rb, Ba), which are concentrated in biotite residue. Zr, Y, and Sr show different distributions with very low D_i^Bt/melt values. Therefore, they are concentrated in the melt during migmatization and formation of crustal magma. It is interesting to note the behavior of Sr, which accumulates in the anatectic melt in equilibrium with garnet–biotite residue. Ba-rich melts can be generated only in the garnet stability field, because biotite-bearing residue concentrates Ba.

The Taukha terrane of the Sikhote-Alin hosts outcrops of rocks with unusual structural and textural features, the compositions of which vary from ultrabasic to intermediate and from subalkaline to alkaline. These are hornblendites, mica–feldspar, amphibole–feldspar, and carbonatite-like rocks of vent facies, a dike of phlogopite–olivine rocks, and a small intrusion of melanocratic amphibole gabbro. The magmatic rocks, together with fluidolites and rodingites, compose explosive structures of Paleocene age. Rodingites were formed via the development of explosive structures resulting from metasomatic replacement of basic vent-facies rocks and small intrusive bodies in sedimentary rocks. The Paleocene explosive structures of the Mokrushinskaya and Shirokopadninskaya areas of the Olginsky ore district and breaking of Triassic carbonaceous silicites are genetically related to Au–Pd–Pt mineralization, the specific features of which are “cupriferous gold” (including the Zn- and Ni-bearing varieties of cuproauride and auricupride), native elements, and intermetallic compounds.

The paper discusses new SHRIMP II data on the absolute age of riebeckite granite of the Elinovskii massif, Gorny Altai, and presents comparative characteristics of the morphology and chemical composition of magmatic and hydrothermal zircon obtained by LA-ICP-MS. It is shown that the revealed differences between the two types of zircon are related to the peculiarities of the fluid regime of granitoid melts. Both types of zircon manifest the tetrad effect of M-type REE fractionation.

The chemical composition, crystal structure, and infrared (IR) spectrum of a hydrated CO₃-bearing analog of manganoeudialyte from alkali pegmatites of the Konder pluton (Khabarovsk krai) are studied. The chemical composition of the mineral corresponds to the formula ^N[Na_6.94H₂O_5.13(Y,REE)_0.58. Pb_0.31K_0.28Ba_0.08]_13.32^M1[Ca_5.09Sr_0.89]_5.98^M2[Mn_1.52³⁺Ti_0.21Mg_0.04Fe^0.033+Al_0.02]_1.82^M3(Si_1.16Nb_0.47)_1.63 M₄(Si)_0.50. ^Z[Zr_3.04Hf_0.03]_3.07(Si₃O₉)₂(Si₉O₂₇)2(CO₃)_0.28 X[(H₂O)_4.45OH_0.04Cl_0.03]_4.52. The IR spectrum contains the following lines (s, strong; sh, shoulder): 455s, 475s, 655, 740s, 925s, 977s, 1010s, 1145, 1420sh, 1504, 1650, 2970sh, 3240sh, 3480 cm^–1. The crystal structure is refined in the \(R\bar 3m\) spatial group, a = 14.243(3), c = 30.371(6) Å, and V = 5336(2) Å for 1393 independent reflections (|F_o| > 4σF with a similarity factor R¹ of 6.5%. The deficit in Na and Cl, the presence of Pb and Ba, and the high degree of hydration of the mineral indicates postcrystallization ion-exchange processes typical of hydrothermal alteration of aegirine–albite rocks of the Konder pluton.