The results of the mass change calculations of major, minor and trace elements suggest that the secondary mineral associations and their zonal arrangement at Gossendorf have been formed by a strongly acidic hydrothermal solution rich in SO42−, which underwent chemical variations by reaction with the latite. H2O could have been of exogenous and/or endogenous origin. The chemical species added to the rock during alteration, SO3, V2O3, and SrO, probably originated from a volcanic source. The mass exchange was accompanied by a moderate average decrease in volume of 6.6%. the difference of elemental gains and losses, shows a net mass loss of about 14.60 g. For one altered rock characterizing theoretically the alteration processes in Gossendorf, mass grains were calculated for SO3, H2O, V and Sr, and mass losses for SiO2, Al2O3, Fe2O3, MnO, Mg0, CaO, Na2O, K2O, P2O5, Cr, Co, Ni, Cu, Zn, Rb, Y, Zr, Nb and Ba with respect to an unaltered latite. The gains depend on the newly formed minerals, the losses, however, on the increase of the porosity in the altered rocks. Drastic differences in gains and losses of certain elements which refer to the different alteration conditions were found to exist not only between different alteration zones but also within such zones. All elements investigated were mobilized during the hydrothermal acid-sulphate alteration process, except Ti, which was selected as the immobile monitor element to calculate mass changes. The associations occur in a zonal arrangement and correspond to the characteristics of the silicic, advanced argillic and argillic alteration terminology. more ABSTRACT The Tertiary latitic rock from Gossendorf, in the Gleichenberg Volcanic Area, Styria, Austria, has in places been completely altered to various associations of the secondary minerals opal-C/-CT, alunite, kaolinite, and montmorillonite. Some of the mineral associations, however, may not be explained by a single alteration process, but must be regarded as the result of multi-stage alteration in which alteration products from weak leaching are super-imposed on alteration products from intense leaching.ĪBSTRACT The Tertiary latitic rock from Gossendorf, in the Gleichenberg Volcanic Area, Styria, Au. The results of experimental alteration tests on the latitic rock in open hydrological systems suggest that these secondary minerals and some of the associations observed in the field as well as their zonal distribution, may have been formed by an originally strongly acid solution rich in SO42- which, undergoing progressive chemical variation by reaction with the rock, exhibits a chemical gradient. These associations occur in a zonal arrangement, in which the innermost part has been totally altered to opal and moreover has retained its original latitic structure. more Summary The latitic rock mined at the Gossendorf open pit in the Gleichenberg Volcanic Area of Styria, Austria, has in places been completely altered to various associations of the secondary minerals opal-C/-CT, alunite, kaolinite and montmorillonite. Abstract reprinted with permission from Elsevier.Summary The latitic rock mined at the Gossendorf open pit in the Gleichenberg Volcanic Area of St.Find a library where document is available.In this contribution, the reaction mechanisms and environmental controls of de-dolomitization are discussed in relation to the durability of concrete under sulfate attack. Infiltration of Ca–SO₄–type ground water into the de-dolomitization zone facilitated calcite and brucite neo-formations at 13 > pH > 10.5 during advanced states of concrete deterioration and subsequently resulted in thaumasite precipitation at pH ~ 8.7. Leaching of hydrated cement phases resulted in IS with a pH ~ 12-13, which promoted incongruent dolomite dissolution. During the initial stage of sulfate attack, ettringite and gypsum formation weakened the concrete's microstructure and initiated ACR. A conceptual reaction model for the portlandite–calcium silicate hydrate (CSH) phases–dolomite–calcium sulfate–calcite–brucite–thaumasite system was developed based on experimental data, hydrochemical modelling, IS chemistry and apparent concrete compositions. Environmental controls and reaction pathways of coupled de-dolomitization and thaumasite formationĭeteriorated concrete and interstitial solutions (IS) were collected from Austrian tunnels to elucidate potential connections between de-dolomitization caused by coupled alkali carbonate reactions (ACR) and thaumasite form of sulfate attack (TSA).
0 Comments
Leave a Reply. |