Zeolites in volcanic-igneous hydrothermal systems: a case study of Pauzhetka geothermal field (Kamchatka) and Oligocene Smrekovec volcanic complex (Slovenia)

Abstract

Production from geothermal reservoirs in volcanic-igneous hydrothermal systems may be disturbed owing to the formation of authigenic minerals that reduce primary porosity and infill fissure systems. Crystallization may be induced by natural processes or human activity related to the reservoir exploitation. In volcanic and volcaniclastic rocks, zeolites and related authigenic silicate minerals commonly develop. Two selected study sitesPauzhetka geothermal field in Russia and Smrekovec volcanic complex in Slovenia are characterized by extensive development of progressive stage medium-and low-temperature propylitization and zeolitization with similar mineral assemblages that reduced original reservoir rock porosity and permeability. Retrograde and overprinting reactions of argillitization commonly enhance porosity and permeability of rocks, but some other reactions, like from prehnite to laumontite, from laumontite to heulandite, and from laumontite to analcime, encountered in the Smrekovec volcanic complex reduced it appreciably. Retrograde reactions recognized in the study sites were not induced by the temperature drop only, but were accompanied by the change in chemical composition of reacting fluids. Chemical composition of interstitial waters produced from exploitation wells in the Pauzhetka geothermal field indicate that propylitic and zeolite facies alteration is related to Na-Cl, slightly alkaline waters, while argillitization involved acidic thermal waters with more complex ion composition.

Dioctahedral Phyllosilicates Versus Zeolites and Carbonates Versus Zeolites Competitions as Constraints to Understanding Early Mars Alteration Conditions

“…They can sorb and protect organic compounds and act as a catalyst for organic-based reactions (Ming & Gooding, 1988;van Bekkum & Kouwenhoven, 1989;Venuto, 1994). Although, zeolite formation in Martian environments has not been widely studied, links between carbonation and clay formation (mainly smectite) from basaltic rocks has already been observed in hydrothermal (natural and laboratory simulated) systems on Earth (Dyer, 2002;Gysi & Stefánsson, 2012a, 2012cKralj, Rychagov, & Kralj, 2010;Stefánsson & Gíslason, 2001;Utada, 1988).…”

Facies architecture of the Upper Oligocene submarine Smrekovec stratovolcano, Northern Slovenia

“…Krnes, Veliki Travnik, Mt. Smrekovec and Roma, consist of lava and coarser volcaniclastic rocks that underwent extensive alteration (Kralj, 1998) under medium-temperature propilitisation conditions (Giggenbach, 1997;Reyes, 1998;Kralj et al, 2010), which locally could have exceeded 280°C.…”

“…16, subsection Ramšak), and hydrothermal alteration is pervasive. Laumontite and prehnite are the most common hydrothermal minerals, and occur as pore and fissure fillings and as replacements of the primary constituents, particularly plagioclases (Kralj, 1998;Kralj et al, 2010).…”

Ways to Minimize Water Usage in Engineered Geothermal Systems

“…As the water cools, minerals will precipitate and must be removed from a closed cycle system. Mineral formation can also occur underground, changing the characteristics of the reservoir (Kralj & Rychagov 2010). If hydraulic fracturing is used to increase porosity, the water returning to the surface will have different flow characteristics and chemical composition than native subsurface water.…”