Details
| Original language | English |
|---|---|
| Pages (from-to) | 1444-1454 |
| Number of pages | 11 |
| Journal | American Mineralogist |
| Volume | 104 |
| Issue number | 10 |
| Early online date | 27 Sept 2019 |
| Publication status | Published - 25 Oct 2019 |
Abstract
The diffusive mass exchange of eight major elements (Si, Ti, Al, Fe, Mg, Ca, Na, and K) between natural, nominally dry shoshonitic and rhyolitic melts was studied at atmospheric pressure and temperatures between 1230 and 1413 °C using the diffusion couple method. For six elements, effective binary diffusion coefficients were calculated by means of a concentration-dependent method to obtain an internally consistent data set. Among these components, the range in diffusivities is restricted, pointing to a coupling of their diffusive fluxes. We find that the calculated diffusivities fit well into the Arrhenius relation, with activation energies (Ea) ranging from 258 to 399 kJ/mol in rhyolitic (70 wt% SiO2) melt and from 294 to 426 kJ/mol in the latitic melt (58 wt% SiO2). Ti shows the lowest Ea, while Si, Fe, Mg, Ca, and K have a similar value. A strong linear correlation is observed between logD0 and Ea, confirming the validity of the compensation law for this system. Uphill diffusion is observed in Al in the form of a concentration minimum in the rhyolitic side of the couple, (at ca. 69 wt% SiO2), and in Na indicated by a maximum in the shoshonitic side (ca. 59 wt% SiO2). Fe shows weak signs of uphill diffusion, possibly due to the contribution of ferric iron. The data presented here extend the database of previously published diffusivities in the shoshonite-rhyolite system (González-García et al. 2017) toward the water-free end and allows us to better constrain the water-dependence of major element diffusion at very low water concentrations. Combining both data sets, we find that logD is proportional to the square root of water concentration for a range between 0 and 2 wt% H2O. These results are of particular interest in the study of mass transfer phenomena in alkaline volcanic systems.
Keywords
- alkaline melts, Chemical diffusion, magma mixing, major elements, Vulcano Island
ASJC Scopus subject areas
- Earth and Planetary Sciences(all)
- Geophysics
- Earth and Planetary Sciences(all)
- Geochemistry and Petrology
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In: American Mineralogist, Vol. 104, No. 10, 25.10.2019, p. 1444-1454.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Interdiffusion of major elements at 1 atmosphere between natural shoshonitic and rhyolitic melts
AU - González-García, Diego
AU - Vetere, Francesco
AU - Behrens, Harald
AU - Petrelli, Maurizio
AU - Morgavi, Daniele
AU - Perugini, Diego
N1 - Funding Information: This research was funded by the European Research Council (ERC) Consolidator Grant ERC-2013-CoG No. 612776—CHRONOS to D. Perugini and by the MIUR-DAAD Joint Mobility Project (grant number 57262582) to F. Vetere and H. Behrens. An Alexander von Humboldt Foundation Senior Research Grant to F. Vetere is also acknowledged.
PY - 2019/10/25
Y1 - 2019/10/25
N2 - The diffusive mass exchange of eight major elements (Si, Ti, Al, Fe, Mg, Ca, Na, and K) between natural, nominally dry shoshonitic and rhyolitic melts was studied at atmospheric pressure and temperatures between 1230 and 1413 °C using the diffusion couple method. For six elements, effective binary diffusion coefficients were calculated by means of a concentration-dependent method to obtain an internally consistent data set. Among these components, the range in diffusivities is restricted, pointing to a coupling of their diffusive fluxes. We find that the calculated diffusivities fit well into the Arrhenius relation, with activation energies (Ea) ranging from 258 to 399 kJ/mol in rhyolitic (70 wt% SiO2) melt and from 294 to 426 kJ/mol in the latitic melt (58 wt% SiO2). Ti shows the lowest Ea, while Si, Fe, Mg, Ca, and K have a similar value. A strong linear correlation is observed between logD0 and Ea, confirming the validity of the compensation law for this system. Uphill diffusion is observed in Al in the form of a concentration minimum in the rhyolitic side of the couple, (at ca. 69 wt% SiO2), and in Na indicated by a maximum in the shoshonitic side (ca. 59 wt% SiO2). Fe shows weak signs of uphill diffusion, possibly due to the contribution of ferric iron. The data presented here extend the database of previously published diffusivities in the shoshonite-rhyolite system (González-García et al. 2017) toward the water-free end and allows us to better constrain the water-dependence of major element diffusion at very low water concentrations. Combining both data sets, we find that logD is proportional to the square root of water concentration for a range between 0 and 2 wt% H2O. These results are of particular interest in the study of mass transfer phenomena in alkaline volcanic systems.
AB - The diffusive mass exchange of eight major elements (Si, Ti, Al, Fe, Mg, Ca, Na, and K) between natural, nominally dry shoshonitic and rhyolitic melts was studied at atmospheric pressure and temperatures between 1230 and 1413 °C using the diffusion couple method. For six elements, effective binary diffusion coefficients were calculated by means of a concentration-dependent method to obtain an internally consistent data set. Among these components, the range in diffusivities is restricted, pointing to a coupling of their diffusive fluxes. We find that the calculated diffusivities fit well into the Arrhenius relation, with activation energies (Ea) ranging from 258 to 399 kJ/mol in rhyolitic (70 wt% SiO2) melt and from 294 to 426 kJ/mol in the latitic melt (58 wt% SiO2). Ti shows the lowest Ea, while Si, Fe, Mg, Ca, and K have a similar value. A strong linear correlation is observed between logD0 and Ea, confirming the validity of the compensation law for this system. Uphill diffusion is observed in Al in the form of a concentration minimum in the rhyolitic side of the couple, (at ca. 69 wt% SiO2), and in Na indicated by a maximum in the shoshonitic side (ca. 59 wt% SiO2). Fe shows weak signs of uphill diffusion, possibly due to the contribution of ferric iron. The data presented here extend the database of previously published diffusivities in the shoshonite-rhyolite system (González-García et al. 2017) toward the water-free end and allows us to better constrain the water-dependence of major element diffusion at very low water concentrations. Combining both data sets, we find that logD is proportional to the square root of water concentration for a range between 0 and 2 wt% H2O. These results are of particular interest in the study of mass transfer phenomena in alkaline volcanic systems.
KW - alkaline melts
KW - Chemical diffusion
KW - magma mixing
KW - major elements
KW - Vulcano Island
UR - http://www.scopus.com/inward/record.url?scp=85073255542&partnerID=8YFLogxK
U2 - 10.2138/am-2019-6997
DO - 10.2138/am-2019-6997
M3 - Article
AN - SCOPUS:85073255542
VL - 104
SP - 1444
EP - 1454
JO - American Mineralogist
JF - American Mineralogist
SN - 0003-004X
IS - 10
ER -