North-Mutnovskoe fumarolic field is the compact group of thermal springs. It locates in the volcano-tectonic zone of the Mutnovsky volcano in an oval deepening with low borders and flat bottom. About 20 strong vapor jets with the charge more than 0.03 kg/sec and temperature 96 – 110 °Ñ are situated there. Hot small lake and tens of mud pots locate on the lowered sites. The thermal field area is 5.5•103 m2.

Whole variety of mud pots was sampled in 2006-2007. In situ pH, Eh, T, and anions Cl-, F-, NO3-, NO2- were measured after some sedimentation of suspension. The samples were filtered using a 0.45 µm membrane filter. Humid solids from mud pot sides were sampled by special sampler on the long handle in thermal proof plastic containers. In laboratory pore waters were pressed out from the samples at 100 atm pressure. Cations and trace elements were measured by an ICP-AES method using IRIS Advantage instrument at the Analytical Center, IGM SB RAS. Content of REE and some other elements were derived using ICP-MS.

The electromagnetic frequency induction soundings were effected at this site at 2007 with NEMFIS (Near surface EM Frequency Induction Sounding) technique, developed in IPGG SB RAS. The geoelectric cross-sections are made along the 5 observation lines. Each cross-section reflects apparent resistivity distribution in the ground.
The compositions of mud pot solutions are various. All solutions correspond to acid and semi-acid waters. Prevailing cations in different pots are Fe2+, Fe3+, Al3+, NH4+, in one of the pots – Ca. In the majority of pots concentration of Fe(II) more than Fe(III). High level of Fe(II) in combination with low redox conditions indicates reducing media in the underground reservoir. Among trace elements the main quota is made with Mn, then Zn, V, Sr, Ba, Ti, Cu, B, Co, Cr, Ni, Li, Be. The main features of solutions are the elevated concentrations V, Ti, Co, Cr, Ni in comparison with other volcanic areas. High concentrations of these elements were determined in mud pots of the Donnoe fumarolic field (Mutnovsky volcano). Uniform geochemical association specifies to uniform deep source of the whole volcanic system. Difference in element concentration can be consequence of structural features.

By geophysical prospection vertical shape of subsurface thermal water springs is recognized. Hydrogeochemical zoning of thermal field interior determines variety of mud pots and springs composition.

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