| Title | Transport and Concentration of Ore Chemical Compounds in the Geothermal Environments |
|---|---|
| Authors | Sergei N. Rychagov, Galina P. Koroleva, Galina P. Sandimirova, Nikolai S. Zhatnuev |
| Year | 2006 |
| Conference | International Mineral Extraction Conference |
| Keywords | geothermal, ore chemical elements, geochemical barriers, concentration, geological blocks, hydrothermal-magmatic system |
| Abstract | Behavior of ore chemical elements at deep-seated, subsurface and aquatic geochemical barriers in hydrothermal systems is discussed. Intense water-rock interaction processes occur within the confines of thick (. 100-300 m) zones of boiling hydrotherms: here, within the interstitial-breccia interior, quartz-adularia (quartz-adularia-prehnite-wairakite) metasomatites are enriched with alkaline, ore and rare chemical elements, or contrariwise (when physical-chemical parameters of the system are altered). the leaching and concentration of these elements occur in hydrothermal fluid. Hydro- and lithochemical anomalies of ore and alkaline elements are formed within the confines of moving tectonic structures, which bring the hydrothermal fluid to near-surface levels. Structure of metal-bearing fluid localization areas is demonstrated. Hypergenesis zones of geothermal deposits (at aquatic and subaquatic barriers) produce geochemical anomalies in kaolinite-montmorillonite clays and siliceous sinters. Structurally, the anomalies are confined to the boundaries or axial zones of elevated blocks. Peculiarities of metal-bearing fluid composition within different geological blocks of deposits are indicated. The most probable forms of transport and concentration of Au, Ag, As etc. by water fluids in the near-surface environment of high-temperature hydrothermal systems are established. Evolution of steam dominant zones within hydrothermal systems is discussed in detail by example of Pauzhetsky geothermal deposit (the South Kamchatka). Thermodynamic and geological-structural conditions of the emergence of steam zones within the confines of cooling magmatic bodies and above-intrusive areas at different depths are shown. A numerical model study for zonesf evolution in space and time at various starting and boundary temperature and host rocks permeability parameters is conducted. The influence of geochemical fluid-steam barrier on processes of mass transfer, namely, on deposition or leaching of gold and silver from the siliceous matrix, and on alteration of composition and properties of hydrothermal fluid and steam is experimentally studied. It is also demonstrated that composition and properties of a liquid phase are profoundly changed during the boiling of saline solutions and repeated expansion and compression of a steam phase. Factual thermodynamic and physical-chemical parameters of the gsteam hydrotherm. rockh system are the base for the development of extraction technologies applied to take useful chemical components from saline solutions, siliceous deposits or other mineral media. The work has been done with a financial support of the Russian Fund of Fundamental Research (project 06-05-64689a) and Russian Association of Geothermal Energy Society. |