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Data indicating the important role of microorganisms in the redistribution of REEs in the weathering crust and the decisive role in the concentration of REEs during the formation of ores in the upper ore horizon of the Tomtor field are obtained. The uptake of REEs was carried out by the community of microorganisms, such as phototrophs, methanogens, methanotrophs, and proteobacteria, which form the basis of the microbiocenosis for this paleoecosystem. The isotopic composition of C carbonates in all samples studied with fossilized microorganisms corresponds to the biogenic one, and the isotopic composition δ18ОSMOW (from 7 to 20‰) indicates the endogenous (hydrothermal) and, to a lesser extent, exogenous nature of the solutions. The low (87Sr/86Sr)I values of carbonates (~0.7036–0.7042) exclude the participation of seawater.

Among the rich REE–Nb ores of the upper ore horizon of the Tomtor deposit, under the Jurassic deposits (borehole 324, interval 47–62 m), ultrapotassiс rocks (feldspar porphyrite), consisting of more than 90% potassium feldspar (K-feldspar), are found. The rocks contain titanium–niobium oxide and rare grains of fersmite, Ce-bastnaesite, Ce-monazite, calcite, barite, and strontianite. K-feldspar is unevenly replaced by muscovite. By the type of REE and element distribution on the multidiagrams, the rock correlates well with the rich REE–Nb ores from the Burannyi site at the lower levels of contents. The Ar–Ar age of K-feldspar corresponds to 323.4 Ma and is correlated with the geological time of the formation of the rich REE–Nb ores from the Tomtor deposit, as well as the time of occurrence of magmatic and hydrothermal activity in this part of the region during this period.

Carbonates of the Tomtor complex of ultramafic alkaline rocks and carbonatites (the northern part of the Republic of Sakha Yakutia) are distinguished by a wide range of carbon isotopic composition δ13C from +2 to –59.9‰. The geological position, localization patterns, mineral and chemical compositions and the relationship with REE mineralization of samples with values of δ13C carbonates from –25 to –59‰ are characterized. The formation of abnormally low δ13C in carbonates is determined by the biogenic oxidation of methane from δ13Cmet to –70‰.

In the northern part of the Siberian Platform, east of the Anabar Shield, several massifs of alkaline rocks with carbonatites identified (Tomtor, Bogdo, Promezhutochnyi) and projected according to geophysical data (Bualkalakh, Chuempe, Uele) form a large alkaline–carbonatite province. The first data on the composition of alkaline rocks of the Bogdo massif indicate that the latter belong to a group of feldspathoid rocks of basic composition: rischorrites, biotite–aegirine liebenerite syenites, carbonatized pseudo-leucite nepheline syenites with symplectites, and nepheline–feldspar aggregates. Sphene grains were extracted from various rocks of the Bogdo massif, and their U‒Pb age was determined using the SHRIMP-II secondary-ion microprobe. The calculated U‒Pb age is 394.4 ± 3.2 Ma, which is similar to the age of the Tomtor massif and the age of the rocks of the Kola alkaline province. One of the reasons for the manifestation of alkaline plume magmatism on this territory may be the effect of the peripheral zone of the African Large Low Shear Velocity Province (“Tuzo”) on the Baltic area and Siberia during the Devonian age.

Mineral processing wastes may be considered as a natural experimental laboratory for study of mineral� ogical and geochemical peculiarities of rocks and ores changes, forms of elements transport and precipita� tion. Wastes often contain significant amounts of valu� able components including precious metals, which are mobilized into solution, are removed beyond tailing pit, and are reprecipitated on different geochemical barriers in the exogenic process. Carbonaceous mate� rial is one of the most effective geochemical barriers accumulating many elements. Coal [1] and black shale [2] are often considered. Peat and peat bog deposits may be active concentrators of different elements as well, but direct estimation of their role in accumula� tion of precious metals is practically nonexistent. This study is aimed at investigation of gold redistribution and its speciation in peat contacting with acid mine drainage solutions formed by interaction of surface waters with mineral processing wastes of the Ursk ore field in the example of the Ursk tailing pit (Kemerovo region, Russia). The Ursk tailing pit, constructed for more than 80 years ago, is composed by the cyaniding wastes of primary auriferous polymetallic, pyrite ores, and that of the oxidation zone of the New Ursk deposit forming two piles with a height of 10–12 m [3, 4]. The average Au content in primary ores reached 4 ppm. During the whole period of tailing pit existence, the unfixed mate� rial of wastes has been washed out by rainfalls and flood waters. The natural creek draining waste piles has been evolving into acid [4]. Wetland with peat bog located downstream of the tailing pit is burned by acid mine drainage solutions and is covered by the trans� ported wastes layer up to 50 cm through to the Ur River (Fig. 1). Remains of swampy tussocks rise above wastes surface. Based on granulometric differentiation of the transported wastes material, three areas were distinguished in a dispersion trains of the tailing pit

The features of present deposits that form in the vicinity of hot springs can provide clues to the parameters of paleowaters in places of past hydrothermal activity marked by remnant carbonate and/or siliceous sinter. We investigated a large carbonate body at the Garga hot spring developing in the Baikal zone of nitric hydrotherms in the Barguzin Rift Zone valley. The main focus was on the structure of the carbonate mound, as well as on the partitioning of radioactive elements between the cyanobacterial mat and the inorganic component of the body (the issue that has never been explored before). The cyanobacterial community of the Garga spring is an active biosorbent of 226Ra, 228Ra, 210Pb. The radionuclides accumulated by biosorption become preserved in minerals that form within the bacterial community. The reported data of mineral formation in the cyanobacterial mat along with the mineralogy and structure of the carbonate mound of the Garga spring have implications for the complex history of the Garga body. It has been produced jointly by precipitation from the venting thermal water (opal-calcite-fluorite-barite-celestine assemblage) and microbial metabolic activity (coarse calcite and thin black encrustation rich in Mn minerals).

The waste is not fixed; during the entire period of the tailing’s existence it is regularly diluted by rainwa� ter and flood water. The ravine’s swampy territory below the tailings down to the Ur river (a confluent of the Inya river) is covered with the derived waste matter (Fig. 2); the area’s vegetation has been destroyed due to the acid mine drainage influence. The derived mat� ter lays over the peat, with swamp hassocks still present. Down in the ravine, in the valley of the river Ur, the waste covers the splinters of limestone.

The oldest lithified cyanobacteria found in sedi� ments date back to 3.6 Ga, and largescale formation of stromatolitic structures associated with copious cyanobacterial mats is known at 2 and 1 Ga (1, 2). Today's cyanobacteria have been expelled to extreme habitats, such as hot springs where thermophilic com� munities can live. Many hot springs vent in the Bar� gusin basin of the Baikal Rift Zone (3-5).They are alkaline waters with high silica concentrations and a nitrogendominated gas phase. The waterbearing rocks are sheared outsized granites or granodiorites. Microbial populations have been recognized at all venting sites (6) (more than ten within the Barguzin basin), but travertine occurs at three sites only (Alla, Garga, and Gusikha) (7).The thickest carbonate (trav� ertine) framework at the Garga spring has been attrib� uted to the microbial activity (8). Yet, minerals depos� ited immediately in the hotspring environments of the basin have never been described. We investigated microbial populations of five springs (Alla, Kuchiger, and Umkhei on the right side of the Barguzin valley, and Garga and Uro on its left side) and discovered bacteriamediated precipitation of amorphous silica and calcite in the Alla and Garga springs, just where travertine is formed. Our objective was to study the morphology of minerals and the laws of their forma� tion in microbial communities. Water samples collected in 2007 and 2008 from the emergent sources and down the stream were filtered through (0.45 µm) membrane filters. Eh and pH, as well as O2 and HS - concentrations, were measured at the site by an Anion 4100 meter and MERCK tests (Germany), respectively. The water chemistry was analyzed by several methods to provide cross valida� tion: atomemission spectrometry, ICPMS, capillary electrophoresis, and atomic absorption. For transpor� tation, the microbial mat samples were packed with caution to preserve their structure, and were split into layers and dried in the laboratory. The element abun� dances in the organic and mineral components of the mats were determined by SRXRF method. The com� munity composition of the mats, and the mineral mor� phology and phase composition were studied on "Carl Zeiss" light microscopes (Axiolab 40 Pol and Axio Imager, Germany) and on a Leo Oxford 1430VP scan� ning electron microscope (SEM) (Germany), analysts S.V. Letov and A.T. Titov. The predominant ions in the water of the Alla springs are bicarbonate, silica and sodium. The emer�