| Abstract |
Ore and silicate mineral formations in the shape of globules and other shapes identified within central parts of modern high temperature hydrothermal-magmatic systems (in geothermal deposits) of the Kuril-Kamchatka island arc were described in detail. Native iron, magnetite globules and zonal ones with iron center and magnetite-iozite rim, as well as more complex ones were identified by means of mineralogical, spectral, microprobe, x-ray phase and other analyses. Globules have traces of Ni, Mn, Ti, Cu etc.. up to 5%, and mark 1.5 km deep opened heat-conducting zones of tectonic faults within horst structures, located above heat (ore) feeding sources of geothermal deposits. It is assumed that these minerals are formed by means of injection of gdryh recovered fluid having a temperature not less than 500-6000„R into metasomatites from a depth. 1.5. 2.0 km. It was established that pyrite disseminated in altered rocks contains traces of numerous ore and non-ore elements in an amount of 3.2%. The fluid injects traces of Fe, Mg, Mn, Ti, Cr, Cu, Pb, Au, Ag, As, Al, Si, K, Na, Ca and others into host rocks. On the whole, these and other element concentrations sustainably increase from early geothermal deposit development phases to the later. Silica, contained in hydrothermae in the form of silica gel, acts as a selective sorbing agent which impacts the ore-bearing properties of hydrothermal solutions, differentiates sorbed metals and transports them. Consideration of geological-geochemical aspects of ore mineral formation and metal-bearing fluids in modern hydrothermal-magmatic systems and geothermal deposits is of principal importance for the development of valuable chemical component extraction technologies to be used in a conductive geothermal environment. The study was supported by the Russian Foundation for Basic Research (project 06-05-64689„p), Presidium of Far East Division RAS (projects 06-III-A-08-332 and 06-III-B-08-371), Russian Association of Geothermal Energy Society and International Geothermal Association. |