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| Titel |
Extreme limestone weathering rates due to micron-scale grain detachment |
| VerfasserIn |
Simon Emmanuel, Yael Levenson |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250094619
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| Publikation (Nr.) |
 EGU/EGU2014-10041.pdf |
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| Zusammenfassung |
| Chemical dissolution is often assumed to control the weathering rates of carbonate
rocks, although some studies have indicated that mechanical erosion could also play
a significant role. Quantifying the rates of the different processes is challenging
due to the high degree of variability encountered in both field and lab settings. To
measure the rates and mechanisms controlling long-term limestone weathering,
we analyse a lidar scan of the Western Wall, a Roman period edifice located in
Jerusalem. Surface retreat rates in fine-grained micritic limestone blocks are found to
be as much as 2 orders of magnitude higher than the average rates estimated for
coarse-grained limestone blocks at the same site. In addition, in experiments that use
atomic force microscopy to image dissolving micritic limestone, we show that these
elevated reaction rates could be due to rapid dissolution along micron-scale grain
boundaries, followed by mechanical detachment of tiny particles from the surface. Our
analysis indicates that micron-scale grain detachment, rather than pure chemical
dissolution, could be the dominant erosional mode for fine-grained carbonate rocks. |
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