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Polona Kralj - One of the best experts on this subject based on the ideXlab platform.
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Hydrothermal zeolitisation controlled by host-rock lithofacies in the Periadriatic (Oligocene) Smrekovec submarine composite stratovolcano, Slovenia
Journal of Volcanology and Geothermal Research, 2016Co-Authors: Polona KraljAbstract:Abstract Hydrothermal zeolites (Laumontite, yugawaralite, analcime, heulandite, clinoptilolite), prehnite and pumpellyite have been recognised in a succession of volcanic, autoclastic, pyroclastic, resedimented volcaniclastic and mixed siliciclastic–volcaniclastic deposits. In cone-building lithofacies association attaining 310 m, the alteration minerals commonly change within a single normally graded depositional unit or alternate in the section on a dm- to m-scale, according to the host-rock lithofacies. Fine-grained deposits rich in juvenile glassy pyroclasts are altered to heulandite and clinoptilolite or analcime, and Laumontite widely occurs in coarse-grained host-rocks (lapilli tuff, hyaloclastite breccia, volcaniclastic breccia, hyaloclastites) and fracture systems. In near-vent lithofacies association attaining 420 m, prehnite–Laumontite, Laumontite–analcime, and Laumontite–heulandite–clinoptilolite zones developed as a result of superimposed thermal regime generated by the emplacement of an over 200 m thick sill. The recognised dependence of alteration on porosity, permeability and fracturing of the host-rock is closely related to hydrological conditions in the stratovolcano-hosted hydrothermal system with convective–advective flow regime. After separation of steam and gases from convecting hydrothermal fluids, denser liquids outflowed intermittently, preferentially through steeply inclined (20–30°) high-permeability layers in the stratovolcano edifice. In low-permeability layers the flow was slow and thermal conditions were mainly attained by conduction. Zeolites developed only in coarse- and fine-grained vitroclastic tuffs, presumably by the dissolution of volcanic glass. The interstratified siliciclastic siltstones, tuffites and resedimented deposits with low content of glassy particles are devoid of zeolites and indicate compositional constraint on zeolitisation. Lava flows, cooling in a submarine environment and undergoing disintegration and mingling with the enclosing water-saturated sediment were individual, ephemeral and spatially localised high-temperature hydrothermal systems favourable for the formation of pumpellyite, prehnite and Laumontite.
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Hydrothermal alteration of chlorite to randomly interstratified corrensite-chlorite: Geological evidence from the Oligocene Smrekovec Volcanic Complex, Slovenia
Applied Clay Science, 2016Co-Authors: Polona KraljAbstract:Abstract Chlorite, ordered mixed-layer chlorite-smectites, Laumontite, quartz and albite are the most widespread alteration assemblage in cone-building and near-vent successions of lavas, autoclastic, pyroclastic and resedimented volcaniclastic deposits of the Oligocene Smrekovec Volcanic Complex, Slovenia. Randomly interstratified corrensite-chlorite with ~ 70–80% of corrensite layers (R0 Cr-Ch) is less common in occurrence and associated either with clinoptilolite and heulandite in fine-grained vitric tuffs, or with prehnite, Laumontite, actinolite, analcime and albite in extensively altered and/or fractured host-rocks. The assemblage with clinoptilolite and heulandite indicates the temperatures of formation of
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Zeolites in volcanic-igneous hydrothermal systems: a case study of Pauzhetka geothermal field (Kamchatka) and Oligocene Smrekovec volcanic complex (Slovenia)
Environmental Earth Sciences, 2010Co-Authors: Polona Kralj, Sergei Rychagov, Peter KraljAbstract: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 sites—Pauzhetka 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.
Bradley R. Hacker - One of the best experts on this subject based on the ideXlab platform.
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Experimental investigation of kinetics and rheology during diagenesis
1998Co-Authors: J.g. Liou, Bradley R. HackerAbstract:Two processes of enormous economic consequence occur within the upper to middle crust: the formation, migration, entrapment, and degradation of hydrocarbons, and hazardous seismicity. Substantial scientific evidence suggests that both these processes are influenced by devolatilization reactions during diagenesis. However, surprisingly few laboratory studies have been conducted on materials actively undergoing low-grade metamorphism or diagenesis. Because of this, there exists no suitable basis for understanding the rates at which devolatilization occurs, and what effects this process has on deformation at shallow to moderate depths in the crust. The authors are conducting a coordinated deformation and kinetic study of an important devolatilization reaction: the breakdown of Laumontite. Laumontite is a common zeolite whose equilibrium phase relations and room-temperature frictional behavior are well understood. Besides serving as a model system for more complicated rocks, Laumontite is an important mineral in its own right, particularly for hydrocarbon fields in sandstones and for fault zones in the crust. Hydrostatic experiments are being conducted to investigate the kinetics and mechanism of Laumontite dehydration, and triaxial deformation experiments will enable characterization of the effect of differential stress on the reaction and the effect of synkinematic dehydration on the mechanical behavior of rock. The authors anticipate results of significant import for hydrocarbon exploration and recovery and for understanding the strength and seismic potential of crustal fault zones.
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Experimental investigation of Laumontite → wairakite+H2O; a model diagenetic reaction
American Mineralogist, 1997Co-Authors: Carlos Jove, Bradley R. HackerAbstract:The rate and mechanism of a key diagenetic reaction, Laumontite → wairakite 1 H2O, have been determined in experiments with durations as long as three months at 5 P HO 2 100 MPa and temperatures of 350‐450 8C. In the lower temperature range, 350‐400 8C, nucleation of wairakite occurred on the smallest Laumontite fragments in the starting material. Growth then proceeded by the dissolution of large Laumontite grains, transport within the fluid, and precipitation of euhedral to subhedral wairakite. At higher temperatures, 425 and 450 8C, each sample contains two product phases: wairakite and an unidentified plagioclase-like phase. The plagioclase-like silicate was stabilized by the uptake of Na and formed early as ;10 mm wide skeletal grains along Laumontite grain boundaries. The wairakite grains subsequently nucleated on and grew into the interiors of large Laumontite grains. Nucleation rates at 425‐450 8C were 10‐100 wairakite grains per square meter of Laumontite surface per second. Growth rates varied from 1.5 3 10 211 m/s at 350 8 Ct o 2.1 3 10 210 m/s at 450 8C; the low-temperature data can be fit with an apparent activation energy of 72 6 13 kJ/mol and a pre-exponential ‘‘interface jump distance’’ of ;1 3 10 218 m. This activation energy and these growth rates are comparable to those calculated by Walther and Wood (1984) to characterize interface-controlled reactions in silicates under H 2Osaturated conditions. Our data predict transformation rates for geologic conditions that are too fast to account for the commonly observed incomplete natural reaction of Laumontite → wairakite, indicating that transformation in nature must be limited by slower nucleation rates or by slower intergranular diffusion—perhaps as a result of lower H 2O activity or slower heating rates.
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experimental investigation of Laumontite wairakite h2o a model diagenetic reaction
American Mineralogist, 1997Co-Authors: Carlos Jove, Bradley R. HackerAbstract:The rate and mechanism of a key diagenetic reaction, Laumontite → wairakite 1 H2O, have been determined in experiments with durations as long as three months at 5 P HO 2 100 MPa and temperatures of 350‐450 8C. In the lower temperature range, 350‐400 8C, nucleation of wairakite occurred on the smallest Laumontite fragments in the starting material. Growth then proceeded by the dissolution of large Laumontite grains, transport within the fluid, and precipitation of euhedral to subhedral wairakite. At higher temperatures, 425 and 450 8C, each sample contains two product phases: wairakite and an unidentified plagioclase-like phase. The plagioclase-like silicate was stabilized by the uptake of Na and formed early as ;10 mm wide skeletal grains along Laumontite grain boundaries. The wairakite grains subsequently nucleated on and grew into the interiors of large Laumontite grains. Nucleation rates at 425‐450 8C were 10‐100 wairakite grains per square meter of Laumontite surface per second. Growth rates varied from 1.5 3 10 211 m/s at 350 8 Ct o 2.1 3 10 210 m/s at 450 8C; the low-temperature data can be fit with an apparent activation energy of 72 6 13 kJ/mol and a pre-exponential ‘‘interface jump distance’’ of ;1 3 10 218 m. This activation energy and these growth rates are comparable to those calculated by Walther and Wood (1984) to characterize interface-controlled reactions in silicates under H 2Osaturated conditions. Our data predict transformation rates for geologic conditions that are too fast to account for the commonly observed incomplete natural reaction of Laumontite → wairakite, indicating that transformation in nature must be limited by slower nucleation rates or by slower intergranular diffusion—perhaps as a result of lower H 2O activity or slower heating rates.
J. R. Boles - One of the best experts on this subject based on the ideXlab platform.
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OXYGEN ISOTOPE MEASUREMENTS OF ALBITE-QUARTZ-ZEOLITE MINERAL ASSEMBLAGES, HOKONUI HILLS, SOUTHLAND, NEW ZEALAND
2015Co-Authors: Mary L. Stallard, J. R. BolesAbstract:Abstract--The oxygen isotopes of albite, quartz, and zeolites from the Hokonui Hills, New Zealand, constrain crystallization temperatures and the type of pore fluids present during diagenesis. A section of altered vitric tufts in this region contains an extremely sharp reaction boundary between a heulandite-chlorite assemblage containing fresh detrital plagiodase and a Laumontite-albite-quartz ssemblage. A Laumontite vein follows the local joint pattern and forms the reaction boundary, suggesting that lau-montitization occurred as a result of fracturing and increased fluid flow during uplift. The albite (~80 = + 15.0)-quartz (6~80 = + 19.9 to + 20.5) geothermometer constrains the temperature of alteration between 145 ~ and 170"(2 with a pore water 6isO of + 1.8 to + 3.5. The tuff was buried to an estimated maximum temperature ofabout 225*(2, indicating that alteration occurred after maximum burial. Framework oxygen was extracted from zeolites by reaction with CIF3 after the zeolites were thermally dehydrated in a vacuum. Laumontite was dehydrated at300"C, and stilbite at 150"C. The precision of the method is typically about + 0.45 ~ Fractionation curves for dehydrated zeolites are based on a general expression from the literature for feldspars, which depends only on the Si/A1 ratio of the mineral. Measured 51sO values for Laumontite in the groundmass of the altered tuff were + 14.4~/~. The Laumontite-quartz pair constrains the temperature to between 139 " and 162"C, in excellent agreement with the albite-quart
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Diagenesis during folding and uplift of the Southland Syncline, new Zealand
New Zealand Journal of Geology and Geophysics, 1991Co-Authors: J. R. BolesAbstract:Post-Jurassic folding and uplift of the Southland Syncline has fractured and faulted a thick sequence of relatively impermeable marine rocks. Laumontite and stilbite crystallised contemporaneous with the deformation from fluids migrating along permeable fractures and faults. Published isotopic analyses of framework oxygen in these zeolites indicate that the veins near the stratigraphic top of the section, relative to those near the base. crystallised in either isotopically light (meteoric) water or at a relatively constant temperature when the section was subvertical. Regardless, the reactions are relatively late and are related to folding and uplift, rather than maximum burial conditions. Laumontite crystals in the veins are nucleation sites for replacement of adjacent country rock ; thus, veins influenced a greater volume of the rock than they occupy
O. Schäf - One of the best experts on this subject based on the ideXlab platform.
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Hydrothermal synthesis of Laumontite, a zeolite
Microporous and Mesoporous Materials, 1998Co-Authors: H. Ghobarkar, O. SchäfAbstract:Abstract Laumontite was synthesized in a wide temperature range (between 30°C and 450°C) by hydrothermal treatment of artificial glasses of composition 1CaO–1Al 2 O 3 –4SiO 2 at 1 kbar H 2 O pressure. The zeolite was always formed with monoclinic symmetry ( C 2/ m , a =15.02 A, b =13.15 A and c =7.71 A, β =113°). A systematic change of crystal shape with temperature was observed, while other different phases coexisted with Laumontite dependent on the temperature range of synthesis. Comparison of the crystal shapes of natural Laumontites with the crystal shapes of synthesized Laumontites allows predictions regarding the formation temperature of the phase.
Carlos Jove - One of the best experts on this subject based on the ideXlab platform.
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Experimental investigation of Laumontite → wairakite+H2O; a model diagenetic reaction
American Mineralogist, 1997Co-Authors: Carlos Jove, Bradley R. HackerAbstract:The rate and mechanism of a key diagenetic reaction, Laumontite → wairakite 1 H2O, have been determined in experiments with durations as long as three months at 5 P HO 2 100 MPa and temperatures of 350‐450 8C. In the lower temperature range, 350‐400 8C, nucleation of wairakite occurred on the smallest Laumontite fragments in the starting material. Growth then proceeded by the dissolution of large Laumontite grains, transport within the fluid, and precipitation of euhedral to subhedral wairakite. At higher temperatures, 425 and 450 8C, each sample contains two product phases: wairakite and an unidentified plagioclase-like phase. The plagioclase-like silicate was stabilized by the uptake of Na and formed early as ;10 mm wide skeletal grains along Laumontite grain boundaries. The wairakite grains subsequently nucleated on and grew into the interiors of large Laumontite grains. Nucleation rates at 425‐450 8C were 10‐100 wairakite grains per square meter of Laumontite surface per second. Growth rates varied from 1.5 3 10 211 m/s at 350 8 Ct o 2.1 3 10 210 m/s at 450 8C; the low-temperature data can be fit with an apparent activation energy of 72 6 13 kJ/mol and a pre-exponential ‘‘interface jump distance’’ of ;1 3 10 218 m. This activation energy and these growth rates are comparable to those calculated by Walther and Wood (1984) to characterize interface-controlled reactions in silicates under H 2Osaturated conditions. Our data predict transformation rates for geologic conditions that are too fast to account for the commonly observed incomplete natural reaction of Laumontite → wairakite, indicating that transformation in nature must be limited by slower nucleation rates or by slower intergranular diffusion—perhaps as a result of lower H 2O activity or slower heating rates.
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experimental investigation of Laumontite wairakite h2o a model diagenetic reaction
American Mineralogist, 1997Co-Authors: Carlos Jove, Bradley R. HackerAbstract:The rate and mechanism of a key diagenetic reaction, Laumontite → wairakite 1 H2O, have been determined in experiments with durations as long as three months at 5 P HO 2 100 MPa and temperatures of 350‐450 8C. In the lower temperature range, 350‐400 8C, nucleation of wairakite occurred on the smallest Laumontite fragments in the starting material. Growth then proceeded by the dissolution of large Laumontite grains, transport within the fluid, and precipitation of euhedral to subhedral wairakite. At higher temperatures, 425 and 450 8C, each sample contains two product phases: wairakite and an unidentified plagioclase-like phase. The plagioclase-like silicate was stabilized by the uptake of Na and formed early as ;10 mm wide skeletal grains along Laumontite grain boundaries. The wairakite grains subsequently nucleated on and grew into the interiors of large Laumontite grains. Nucleation rates at 425‐450 8C were 10‐100 wairakite grains per square meter of Laumontite surface per second. Growth rates varied from 1.5 3 10 211 m/s at 350 8 Ct o 2.1 3 10 210 m/s at 450 8C; the low-temperature data can be fit with an apparent activation energy of 72 6 13 kJ/mol and a pre-exponential ‘‘interface jump distance’’ of ;1 3 10 218 m. This activation energy and these growth rates are comparable to those calculated by Walther and Wood (1984) to characterize interface-controlled reactions in silicates under H 2Osaturated conditions. Our data predict transformation rates for geologic conditions that are too fast to account for the commonly observed incomplete natural reaction of Laumontite → wairakite, indicating that transformation in nature must be limited by slower nucleation rates or by slower intergranular diffusion—perhaps as a result of lower H 2O activity or slower heating rates.