Although it has already been shown that calcareous stone can be consolidated by 9 using a bacterially-inoculated culture media, a more user-friendly method is the in situ 10 application of a sterile culture media that is able to activate, among the microbial 11 community of the stone, those bacteria with a potential for calcium carbonate 12 precipitation. In order to test this new method for stone consolidation, non-sterilized 13 decayed porous limestone was immersed in sterile nutritional media. Results were 14 compared to those of the runs in which stone sterilized prior to the treatment was used. 15The effects of the microbial community on stone consolidation were determined by 16 recording the evolution of the culture media chemistry. The treated stone was tested for 17 mechanical resistance and porosity. Results demonstrate that the tested media were able 18 to activate bacteria from the microbial community of the stone. As a consequence of the 19 growth of these bacteria, an alkalinization occurred that resulted in calcium carbonate 20 precipitation. The new precipitate was compatible with the substrate and consolidated 21 the stone without pore plugging. Therefore, a good candidate to in situ consolidate 22 decayed porous limestone is the application of a sterile culture media with the 23 characteristics specified in the present study. 24
24HRTEM textural evidence shows that clay minerals in the Tinguiririca geothermal 25 field (Andean Cordillera, central Chile) are the result of direct alteration of former 26 volcanic glass and minerals by hydrothermal fluids at similar temperatures to the 27 present day. They show the classical pattern of diagenetic transformation from 28 * Corresponding author. Tel.: +56-2-29784539; Fax: +56-2-26963050 E-mail address: mvazquez@ing.uchile.cl (M.Vázquez) 2 smectite at the top to illite at the bottom, with the progressive formation of 1 corrensite and chlorite. The high fluid/rock ratio, disposability of necessary 2 cations and absence of previous detrital phyllosilicates allow the consideration of 3 this area as a natural laboratory to establish the extreme ideal conditions for very 4 low-T reactions. Transformations from smectite to R1 illite-smectite (I-S) and from 5 these to R3 mixed-layers occur respectively at 80-120ºC and 125-180ºC. In spite 6 of ideal genetic conditions, the new-formed minerals show all the defective 7 character and lack of textural and chemical equilibrium previously described in 8 the literature for diagenetic and hydrothermal low-temperature assemblages. 9Chemistry of smectite-illite phases evolves basically through a diminution of the 10 pyrophyllitic component toward a theoretical muscovite (Si 4+ +☐ -> Al 3+ +K + ). 11However, a second chemical vector (Si 4+ +Mg 2+ -> Al 3+ +Al 3+ ), that is, decreasing 12 of the tschermack component, also contributes to the evolution toward the less 13Si-more Al rich muscovite in relation to the original smectite. Residual Mg (and 14 Fe) from the latter reaction is consumed in the genesis of chloritic phases.
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