The protoliths of the Early Proterozoic metamorphic complex in the Batomga granite-greenstone terrane are proved to comprise two petrochemical series of volcanic rocks: calc-alkaline and komatiite-tholeiite. The metavolcanic rocks of the calc-alkaline series are metamorphosed basalts, andesites, dacites, and rhyolites. The topology of the trace-element patterns of the acid volcanics is similar to that of Archean gray gneisses in platform basements, and this suggests that the petrologic mechanisms that produced the protoliths could be similar. The metavolcanics of the komatiite-tholeiite series are determined to include komatiite and tholeiite basalts. Their chemical composition is consistent with the fractionation model of high-Mg basalts in intermediate chambers under low pressures. The Nb, Y, and Zr concentrations of the metatholeiites testify that their parental melts were derived from a plume source. The metamorphic culmination parameters of the rocks corresponded to the boundary between the amphibolite and granulite facies of elevated pressure.

В составе раннепротерозойского метаморфического комплекса Батомгской гранит-зеленокаменной области среди магматических протолитов выделены две петрохимические серии вулканитов: известково-щелочная и коматиит-толеитовая. Метавулканиты известково-щелочной серии представлены метабазальтами, метаандезитами, метадацитамии, метариолитами. Спектр распределения элементов-примесей в кислых метавулканитах имеет сходную топологию с архейскими серыми гнейсами фундамента платформ, что может свидетельствовать о близком петрологическом механизме формирования их протолитов. Среди метавулканитов коматиит-толеитовой серии выделены коматиитовые и толеитовые базальты. Их химизм согласуется с моделью фракционирования высокомагнезиальных базальтов в промежуточных камерах при низких давлениях. Содержание Nb, Y, Zr в метатолеитах свидетельствует о том, что их исходные расплавы имеют плюмовый источник. Кульминационные условия метаморфизма пород комплекса по температуре соответствуют граничной области амфиболитовой и гранулитовой фаций повышенных давлений.

The accumulations of massive sulfides, mostly pyrrhotite, and the accompanying Pt-Pd and gold mineralization in the more eroded Lantar part of the Dzhugdzhur massif-type anorthosite, Aldan Shield, Russia, are characterized in detail for the first time. The metamorphic basement host-rocks of the anorthosite massif are crosscut by interlayers and injections of pyroxenite and plagioclase peridotite, which have a different extent of pyrrhotite dissemination. Upward, they give way to olivine-bearing gabbronorites interlayered with bodies of sulfide-bearing pyroxenite and gabbro. Above is a zone 350 m thick of pegmatitic gabbroic anorthosites which hosts the main bulk of the sulfide ores of Nyandoma and Batomga areas. These areas differ from one another by intensity of occurrence of the massive and disseminated pyrrhotite, chalcopyrite nests, and late pyrite-bearing assemblages. Platinum-palladium mineralization is represented by moncheite, sperrylite and kotulskite. Copper-, silver-, and Pt-Pd-bearing gold is found in the pyrite concentrate.

New geochemical data are discussed on the magmatic complexes of the Koksharovka alkaline ultrabasic massif of Late Jurassic age obtained by the ICP-MS method. Based on the first results on rare earth geochemistry of carbonatites and associating pyroxenites and geological observations, the magmatic origin of the Koksharovka carbonatites was substantiated, and the problems of formation of accompanying igneous rocks were considered.

This paper reports the first U-Pb geochronological data on the Precambrian granitoids of the Batomga block (Aldan shield). It was established that the amphibole diorites of this block have an age of 2062 ± 14 Ma, while biotite granites are dated at 2055 ± 7 Ma. These granitoids were subjected to epidote-amphibolie facies metamorphism 1920 ± 8 Ma ago.

New geochemical data are presented on the magmatic rocks of the Late Jurassic Koksharovka alkaline-ultrabasic massif, which is associated with deposits of vermiculite, apatite, V-bearing titanomagnetite, and placer isoferroplatinum. The REE geochemistry and strontium, oxygen, and carbon isotopic composition of carbonatites and related ijolites and pyroxenites, together with geological observations, point to the magmatic origin of the Koksharovka carbonatites. The origin of associated magmatic rocks is discussed. Trace element modeling of partial melting of mantle sources was conducted to decipher the genesis of the melts of the Koksharovka carbonatites and host titanite-kaersutite pyroxenites.

Isoferroplatinum of two generations (early high-temperature and late) dominantly represent the platinum group mineralogy of the Kondyor zonal alkali-ultrabasic massif. The minor PGM are the Os-Ir-Rh-Pt solid solutions (including native Pt, Os, Ir and Ru) of the magmatic stage as well as the post-magmatic minerals: tetraferroplatinum, tulameenite, hongshiite, minerals of the erlichmanite-laurite and irarsite-hollingworthite series, sperrylite, and others. The latter minerals form rims around isoferroplatinum and inclusions at its edge. Gold is closely associated with bismuthides, antimonides, and tellurides of Pt and Pd and occurs as a pure metal or alloys with Ag (up to aurum silver), copper-platinum and copper-palladium, ranging in composition from Au(3)Cu to AuCu(3).

The bottom of the stratigraphic sequence of the Dzhugdzhur deep-seated granulite complex was determined to consist of a stratified metabasite-enderbite association. The distributions of major and trace elements indicate that the protoliths of the association were volcanic rocks of the calc-alkaline, komatiite-tholeiite, and picrite series. The model assumed for the genesis of the protolithic volcanics of the metabasite-enderbite association includes two stages. The first of them was responsible for the decompression-induced partial melting of the material of an ascending mantle plume with the derivation of melts of the komatiite-tholeiite series. During the second stage, the volcanics of the calc-alkaline series were produced by the partial melting of the metabasite crust under the effect of the heat of the ascending mantle plume. The protoliths of the metabasite-enderbite association were formed in the Early Proterozoic.

Les mineraux du groupe du platine provenant du complexe de Konder, ultrabasique, alcalin et zone, situe a l'est du bouclier d'Aldan, en Russie orientale, sont surtout representes par l'isoferroplatine, formeen deux generations, les deux ayant des teneurs en fer allant de 7.5 a 11.5% (poids). Une generation de haute temperature est saturee avec les autres elements du groupe du platine sous forme d'impuretes: jusqu'a 5.3% Ir, 2.9% Os, et 1.8% Rh (base ponderale). En revanche, l'isoferroplatine tardif contient moins de 1.9% Ir, 1.0% Os, et 0.6% Rh. Parmi les mineraux accessoires du groupe du platine, on trouve une grande variete de solutions solides faisant partie du systeme Os-Ir-Rh-Pt, tetraferroplatine, tulameenite, hongshiite, mineraux des series erlichmanite-laurite et irarsite-hollingworthite, sperrylite, bismuthures, antimoniures, tellurures, stannures, et hydroxydes. Les assemblages contiennent possiblement de nouvelles especes minerales: ruthenium natif, l'analogue palladifere de la hongshiite, Pt 2 As 3 , et l'analogue platinifere de la konderite et de l'inaglyite, entre autres, qui forment des liseres autour des grains d'isoferroplatine et des inclusions dans cette phase. Nous observons pour l'or une morphologie et une distribution semblables a celles de l'isoferroplatine; l'or est lie a de rares lentilles de sulfures et des impregnations dans la dunite (or de haute temperature, porteur de Cu, Pt, et Pd), et des venues de monzodiorite recoupant la dunite (or en moyenne ou faible teneurs, a faible contenu en impuretes).

Gold occurring in the platinum placer of the Konder alkaline-ultrabasic massif is represented by the following varieties: copper gold (6.9-25.0 wt % Cu; single grain with 44.3 wt % Cu)-Au3Cu (cuproauride), AuCu (tetraauricupride), and rare AuCu3 (auricupride); copper-platinum (up to 11.8 wt % Pt)-(Au, Pt)Cu; and copper-palladium (up to 10.3 wt % Pd)-(Au, Pd)Cu; as well as silver alloys (up to 62.7 wt % Ag and 4.8 wt % Cu)-from Au, Au-3(Ag, Cu) to electrum and kustelite. Together with individual grains, gold also forms rims and microinclusions at the margins of cubic crystals of low-impurity high-Fe isoferroplatinum (9.5-11.5 wt % Fe) derived from phlogopite-magnetite clinopyroxenites (Nekrasov et al., 1994). This gold variety was not found in association with other types of the Konder nuggets genetically related to dunites, i.e., with those (a) of irregular shape with a significant admixture of chromite crystals and (b) rounded with rare chromite inclusions. The gold minerals and alloys are accompanied by various minerals of platinum-group elements (PGE), e.g., tetraferroplatinum, tulameenite, Pd-hongshiite, complex sulfides and arsenides of Pd and Pt, as well as antimonides, bismuthides, tellurides, stannides, plumbides, palladium germanide, ctc. According to experimental and geochemical data (Nekrasov et al., 1994; this paper), the Ag-Cu-Ag alloys of the Konder massif were formed at 200-450'C and low f(O2) (10(-15) to 10(-25)) and f(S2) (Up to 10(-25)). According to X-ray diffraction data, the silver gold is disordered and has a face-centered cubic lattice. The copper cold has a tetragonal cell with the degree of ordering decreasing from CuAu to CuAu3 and Au.