ENDOGENOUS METALLOGENY IN THE AREA OF ANGARO-VITIMSKI BATHOLITH

Ripp G.S.

Geological Institute SB RAS, Ulan-Ude, Russia, ripp@gin.bscnet.ru

There are manifestations of iron, lead, zinc, molybdenum, tungsten, tin and other treasures of the soil in the area of Angaro-Vitimski batholit. There are not any geochronological studies most of them. We can suppose that these manifestations are in connection with magmatism of Angaro-Vitimski batholit, because we don’t have any other magmatism. At the same time it is not inconceivable connection of some manifestations with Early Paleozoic and Rithean.

All types of mineralization in the area of batholit present by two group. The first group included manifestations of iron and lead-zinc ores, other group included granitic elements (Mo, W, Sn, Be, Ta-Nb). The first group connections with adjoining rocks and can be earlier than granites. We know about presences of ore’s xenoliths in granites, and this granites cross them. Ores of some manifestations are regenerate. Skarn formation connections with granitic intrusion. Leads of ore are present B-type, and leads with higher radioactive isotopes are typical. Sulfur of this group has crust source. It is heterogeneous and heavy (to 10-23‰ δ ³⁴S), and in some minerals isotope nonequilibrium is notes.

Some deposits of iron-ore are known in Kurbinski, (Mildilgen, Muhor-Gorhon), Eravninski (Solongo, Ukir, Sobolka, Gurvunur) and Kondinski (Souhusan, Ursa-Nur) ores districts. They are magnetite ores, which are associating with skarns and hydrosilicas paragenesis. Some skarn deposits are accompanied by high concentration of boron.

Polymetallic mineralization is presented by hydrothermal type (Mungut, Nahoi-Dosho, Hudak), sometimes it is accompanied by skarns (Hakusi). Sometimes it is associated with magnetite (Dovlatka), enriched by tin, barite (Namaminskoe, Ioko, Ribache), gold (Troickoe). These minaralisations form just small deposits.

Molybdenic and tungsten mineralization is widespread among granitic elements and tin, beryllium, tantal-niobium is less. Concentration of these mineralisation is not big and forms small deposits.

Molybdenic mineralization is founding in granitic pegmatites, greisens, skarns, hydrothermal veins and microveins. Skarns are situated in exoconact with granites, diorites, syenites (Hakusinskoe, Kotorokonskoe, Hutaga, Fuglovskoe, Semenovskoe). Sometimes they contain magnetite (Alanga-IV) ores enriched by scheelite (Nizhne-Ikatskoe).

Hydrotermal mineralization is widespread. They are stockworks or microveins, consisting of quartz-molybdenite (Altan, Zum-Buruki, Gongota, Harasan, Dilimdikskoe, Malo-Kurbinskoe). There are some concentrations of sulphide (mainly pyrite), muscovite, fluorite. Scheelite, magnetite, sulphides of lead, zinc, copper in this bodies.

Manifestations of molybdenum greisens (Verhne-Amandakskoe, Tarasovskoe, Solongo, Altan, Sivokon) is accompanied by coarse muscovitezation, sometimes by line zones with sharp contact (Kuitun, Gindzhigenskoe, Galinskoe, Dolinnoe, Aro-Borhen). Molybdenite in it concerned with quartz veins and microveins.

Tungsten mineralization often concerned with scheelite. This mineral accompanies skarns. (Harasan, Amolskoe, Olan, Muhor-Gorhon, Veseli) and hydrothermal quartz veins, microveins (Scalistoe, Kazacha Polyana, Granitnoe, Pravo-Asiktinskoe, Baisinskoe). Skarns consist of garnets, pyroxene, vesuvianite, epidote, amphibole and sometimes include molybdenite (Amolskoe, Marektanskoe). Hydrothermal and skarn deposits are characterized by light concentration, which accompanied sulfide mineralization. Mostly it is pyrite, rarely – sulfides of lead, zinc, copper, sulphosalt. Silicification, some muscovitezation, tremolitezation are widespread in bearing strata. Also isolated quartz- wolframitic manifestations are known.

Tin mineralization presented by granitic pegmatite (Udinskoe) which contains tinstone, skarns (Levo-Kidzhimitskoe, Visotnoe, Ara-Zazinskoe) and hydrotermolites. Tinstone-sulfide (Amalatskoe, Saizhekonskoe, Sivokonskoe, Parenga), quartz-tinstone (Imskoe, Butinskoe, Varvarinskoe), tinstone-silicate-sulfidic (Kidzhimitskoe, Epidotovoe, Hakusinskoe, Sredne-Altanskoe) and tin-polymetallic (Kidzhimitskoe area, China-Amalatskoe country between two rivers) formations are spread in hydrothermalites. Some portion of tin concerned with stannite, and dispersions in ore (blende, magnetite) and silicate (garnet, episode) minerals as isomorphous dirt.

There are pyrite, pyrrhotite, fluorite in manifestations of tinstone-sulfide formations. Tinstone-silicate-sulfide formation is accompanied by quartz-tourmaline, diopside- plagioclase-actinolite-quartz metasomatites. This mineralization concerned with quartz, quartz-tourmaline, quartz-arsenopyrite microveins. There are some sections of greisenization in manifestations, which contain impregnation of wolframite, scheelite, bismuthine.

Isotopic composition of sulfide sulfur in molybdenic, tungsten and tin manifestations is heterogeneous and weighted; vary from 4.4 to +11.9 ‰ δ ³⁴S.

Tantal-niobium mineralization. Segments of albitization in apical part of some granitic massifs (Amnynninski, Oimurski, Muiski, Bezimyanski, Saivoninski) concerned with dissipated tantal-niobium (columbite, pyrochlor, fergusonite, samarskite) mineralization, tinstone, zircon, muscovite, fluorite, topaz, TR-minerals (fluocerite, yttrofluorite, allanite).

Granitic mineralization of Angaro-Vitimski batholite differs from mineralization of riftogenic intraplate magmatism:

- high concentration of volatiles (F, S), potassium, is characteristic feature of Mesozoic mineralization. This mineralization accompanied by high concentration of fluorite, sulphides, muscovite, potash feldspar;

- there is addition of mantel substance in region of ore formation. The composition of sulfide sulfur, oxygen, carbon in deposits and manifestations is intimate with composition of mantel source;

- most of ores are characterized by complicated composition. Minerals of beryllium, molybdenum, tungsten, sulphides of lead, zinc, copper, bismuth and minerals with fluorine (fluorite, topaz, micas) are associating.