Abstract
Using an approach combining high-resolution and energy-filtered transmission electron microscopy (HRTEM and EFTEM), we have studied with Å to nm-spatial resolution the interfacial region that delimits the near-surface altered zone and non-altered labradorite feldspar after dissolution under acid pH conditions. The interface is characterized by extremely sharp and spatially coincident changes in structure and chemistry. The 500-nm-thick altered zone is depleted in interstitial cations (Ca, Na, K) and Al, a framework element, whereas it is enriched in H, O, and Si. Modeling H+ -alkali interdiffusion within a 500-nm-thick altered zone shows that volume interdiffusion cannot reproduce the sharp chemical interfaces measured by EFTEM. Based on these new data, we propose that the near-surface altered zone is a result of interfacial dissolution-reprecipitation, and not of preferential leaching of cations and interdiffusion with H+. This implies an intrinsic dissolution process that is stoichiometric, where the breaking of bonds and release of interstitial cations and framework elements (Al, Si, and O) to solution occur contemporaneously at equal relative rates from the original fluidmineral interface.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 192-197 |
| Number of pages | 6 |
| Journal | Physics and Chemistry of Minerals |
| Volume | 30 |
| Issue number | 4 |
| DOIs | |
| State | Published - May 2003 |
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Keywords
- EFTEM and HRTEM
- Feldspar dissolution
- Interfacial dissolution-reprecipitation mechanism
- Leached layers and preferential cation release
ASJC Scopus subject areas
- Geochemistry and Petrology
- Materials Science(all)
Cite this
An EFTEM/HRTEM high-resolution study of the near surface of labradorite feldspar altered at acid pH : Evidence for interfacial dissolution-reprecipitation. / Hellmann, R.; Penisson, J. M.; Hervig, Richard; Thomassin, J. H.; Abrioux, M. F.
In: Physics and Chemistry of Minerals, Vol. 30, No. 4, 05.2003, p. 192-197.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - An EFTEM/HRTEM high-resolution study of the near surface of labradorite feldspar altered at acid pH
T2 - Evidence for interfacial dissolution-reprecipitation
AU - Hellmann, R.
AU - Penisson, J. M.
AU - Hervig, Richard
AU - Thomassin, J. H.
AU - Abrioux, M. F.
PY - 2003/5
Y1 - 2003/5
N2 - Using an approach combining high-resolution and energy-filtered transmission electron microscopy (HRTEM and EFTEM), we have studied with Å to nm-spatial resolution the interfacial region that delimits the near-surface altered zone and non-altered labradorite feldspar after dissolution under acid pH conditions. The interface is characterized by extremely sharp and spatially coincident changes in structure and chemistry. The 500-nm-thick altered zone is depleted in interstitial cations (Ca, Na, K) and Al, a framework element, whereas it is enriched in H, O, and Si. Modeling H+ -alkali interdiffusion within a 500-nm-thick altered zone shows that volume interdiffusion cannot reproduce the sharp chemical interfaces measured by EFTEM. Based on these new data, we propose that the near-surface altered zone is a result of interfacial dissolution-reprecipitation, and not of preferential leaching of cations and interdiffusion with H+. This implies an intrinsic dissolution process that is stoichiometric, where the breaking of bonds and release of interstitial cations and framework elements (Al, Si, and O) to solution occur contemporaneously at equal relative rates from the original fluidmineral interface.
AB - Using an approach combining high-resolution and energy-filtered transmission electron microscopy (HRTEM and EFTEM), we have studied with Å to nm-spatial resolution the interfacial region that delimits the near-surface altered zone and non-altered labradorite feldspar after dissolution under acid pH conditions. The interface is characterized by extremely sharp and spatially coincident changes in structure and chemistry. The 500-nm-thick altered zone is depleted in interstitial cations (Ca, Na, K) and Al, a framework element, whereas it is enriched in H, O, and Si. Modeling H+ -alkali interdiffusion within a 500-nm-thick altered zone shows that volume interdiffusion cannot reproduce the sharp chemical interfaces measured by EFTEM. Based on these new data, we propose that the near-surface altered zone is a result of interfacial dissolution-reprecipitation, and not of preferential leaching of cations and interdiffusion with H+. This implies an intrinsic dissolution process that is stoichiometric, where the breaking of bonds and release of interstitial cations and framework elements (Al, Si, and O) to solution occur contemporaneously at equal relative rates from the original fluidmineral interface.
KW - EFTEM and HRTEM
KW - Feldspar dissolution
KW - Interfacial dissolution-reprecipitation mechanism
KW - Leached layers and preferential cation release
UR - http://www.scopus.com/inward/record.url?scp=0037789503&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0037789503&partnerID=8YFLogxK
U2 - 10.1007/s00269-003-0308-4
DO - 10.1007/s00269-003-0308-4
M3 - Article
AN - SCOPUS:0037789503
VL - 30
SP - 192
EP - 197
JO - Physics and Chemistry of Minerals
JF - Physics and Chemistry of Minerals
SN - 0342-1791
IS - 4
ER -