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| Titel |
Transport processes at quartz–water interfaces: constraints from hydrothermal grooving experiments |
| VerfasserIn |
K. Klevakina, J. Renner, N. Doltsinis, W. Adeagbo |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1869-9510
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| Digitales Dokument |
URL |
| Erschienen |
In: Solid Earth ; 5, no. 2 ; Nr. 5, no. 2 (2014-08-27), S.883-899 |
| Datensatznummer |
250115333
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| Publikation (Nr.) |
 copernicus.org/se-5-883-2014.pdf |
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| Zusammenfassung |
| We performed hydrothermal annealing experiments on quartzite samples at
temperatures of 392 to 568 °C and fluid pressures of 63 to 399 MPa
for up to 120 h, during which hydrothermal grooves developed on the free
surfaces of the samples. An analysis of surface topology and groove
characteristics with an atomic force microscope revealed a range of surface
features associated with the simultaneous and successive operation of several
processes partly depending on crystal orientation during the various stages
of an experiment. Initially, dissolution at the quartzite-sample surface
occurs to saturate the fluid in the capsule with SiO2. Subsequently,
grooving controlled by diffusion processes takes place parallel to
dissolution and precipitation due to local differences in solubility.
Finally, quench products develop on grain surfaces during the termination of
experiments. The average groove-root angle amounts to about 160°, varying
systematically with misorientation between neighboring grains and depending
slightly on temperature and run duration. The grooving is thermally
activated, i.e., groove depth ranging from 5 nm to several micrometers for
the entire suite of experiments generally increases with temperature and/or
run time. We use Mullins' classical theories to constrain kinetic parameters
for the transport processes controlling the grooving. In the light of
previous measurements of various diffusion coefficients in the system
SiO2–H2O, interface diffusion of Si is identified as the most
plausible rate-controlling process. Grooving could potentially proceed faster
by diffusion through the liquid if the fluid were not convecting in the
capsule. Characteristic times of healing of microfractures in hydrous
environments constrained from these kinetic parameters are consistent with
the order of magnitude of timescales over which postseismic healing occurs in
situ according to geophysical surveys and recurrence intervals of
earthquakes. |
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