Details
| Original language | English |
|---|---|
| Pages (from-to) | 50-59 |
| Number of pages | 10 |
| Journal | Chemical geology |
| Volume | 290 |
| Issue number | 1-2 |
| Early online date | 9 Sept 2011 |
| Publication status | Published - 7 Nov 2011 |
Abstract
Viscosities of shoshonitic and latitic melts, relevant to the Campi Flegrei caldera magmas, have been experimentally determined at atmospheric pressure and 0.5GPa, temperatures between 840K and 1870K, and H2O contents from 0.02 to 3.30wt.%.The concentric cylinder technique was employed at atmospheric pressure to determine viscosity of nominally anhydrous melts in the viscosity range of 101.5-103Pas. The micropenetration technique was used to determine the viscosity of hydrous and anhydrous melts at atmospheric pressure in the high viscosity range (1010Pas). Falling sphere experiments were performed at 0.5GPa in the low viscosity range (from 100.35 to 102.79Pas) in order to obtain viscosity data of anhydrous and hydrous melts. The combination of data obtained from the three different techniques adopted permits a general description of viscosity as a function of temperature and water content using the following modified VFT equation:logη=-a+bT-c+dT-e·expg·wTwhere η is the viscosity in Pa·s, T the temperature in K, w the H2O content in wt.%, and a, b, c, d, e, and g are the VFT parameters. This model reproduces the experimental data (95 measurements) with a 1σ standard deviation of 0.19 and 0.22 log units for shoshonite and latite, respectively. The proposed model has been applied also to a more evolved composition (trachyte) from the same area in order to create a general model applicable to the whole compositional range of Campi Flegrei products.Moreover, speed data have been used to constrain the ascent velocity of latitic, shoshonitic, and trachytic melts within dikes. Using petrological data and volcanological information (geometrical parameters of the eruptive fissure and depth of magma storage), we estimate a time scale for the ascent of melt from 9. km to 4. km depth (where deep and shallow reservoirs, respectively, are located) in the order of few minutes. Such a rapid ascent should be taken into account for the hazard assessment in the Campi Flegrei area.
Keywords
- Campi Flegrei, Concentric cylinder, Falling sphere, Latites, Micropenetration, Shoshonites
ASJC Scopus subject areas
- Earth and Planetary Sciences(all)
- Geology
- Earth and Planetary Sciences(all)
- Geochemistry and Petrology
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In: Chemical geology, Vol. 290, No. 1-2, 07.11.2011, p. 50-59.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - A general viscosity model of Campi Flegrei (Italy) melts
AU - Misiti, V.
AU - Vetere, F.
AU - Freda, C.
AU - Scarlato, P.
AU - Behrens, H.
AU - Mangiacapra, A.
AU - Dingwell, D. B.
N1 - Funding Information: This work has been supported by the INGV-DPC Project V1-UNREST , by the EU Volcanic Dynamics Research and Training Network , and by the German Science Foundation (funding came from a project related to the drilling in the Campi Flegrei). We would like also to thank O. Diedrich for FTIR sample preparations.
PY - 2011/11/7
Y1 - 2011/11/7
N2 - Viscosities of shoshonitic and latitic melts, relevant to the Campi Flegrei caldera magmas, have been experimentally determined at atmospheric pressure and 0.5GPa, temperatures between 840K and 1870K, and H2O contents from 0.02 to 3.30wt.%.The concentric cylinder technique was employed at atmospheric pressure to determine viscosity of nominally anhydrous melts in the viscosity range of 101.5-103Pas. The micropenetration technique was used to determine the viscosity of hydrous and anhydrous melts at atmospheric pressure in the high viscosity range (1010Pas). Falling sphere experiments were performed at 0.5GPa in the low viscosity range (from 100.35 to 102.79Pas) in order to obtain viscosity data of anhydrous and hydrous melts. The combination of data obtained from the three different techniques adopted permits a general description of viscosity as a function of temperature and water content using the following modified VFT equation:logη=-a+bT-c+dT-e·expg·wTwhere η is the viscosity in Pa·s, T the temperature in K, w the H2O content in wt.%, and a, b, c, d, e, and g are the VFT parameters. This model reproduces the experimental data (95 measurements) with a 1σ standard deviation of 0.19 and 0.22 log units for shoshonite and latite, respectively. The proposed model has been applied also to a more evolved composition (trachyte) from the same area in order to create a general model applicable to the whole compositional range of Campi Flegrei products.Moreover, speed data have been used to constrain the ascent velocity of latitic, shoshonitic, and trachytic melts within dikes. Using petrological data and volcanological information (geometrical parameters of the eruptive fissure and depth of magma storage), we estimate a time scale for the ascent of melt from 9. km to 4. km depth (where deep and shallow reservoirs, respectively, are located) in the order of few minutes. Such a rapid ascent should be taken into account for the hazard assessment in the Campi Flegrei area.
AB - Viscosities of shoshonitic and latitic melts, relevant to the Campi Flegrei caldera magmas, have been experimentally determined at atmospheric pressure and 0.5GPa, temperatures between 840K and 1870K, and H2O contents from 0.02 to 3.30wt.%.The concentric cylinder technique was employed at atmospheric pressure to determine viscosity of nominally anhydrous melts in the viscosity range of 101.5-103Pas. The micropenetration technique was used to determine the viscosity of hydrous and anhydrous melts at atmospheric pressure in the high viscosity range (1010Pas). Falling sphere experiments were performed at 0.5GPa in the low viscosity range (from 100.35 to 102.79Pas) in order to obtain viscosity data of anhydrous and hydrous melts. The combination of data obtained from the three different techniques adopted permits a general description of viscosity as a function of temperature and water content using the following modified VFT equation:logη=-a+bT-c+dT-e·expg·wTwhere η is the viscosity in Pa·s, T the temperature in K, w the H2O content in wt.%, and a, b, c, d, e, and g are the VFT parameters. This model reproduces the experimental data (95 measurements) with a 1σ standard deviation of 0.19 and 0.22 log units for shoshonite and latite, respectively. The proposed model has been applied also to a more evolved composition (trachyte) from the same area in order to create a general model applicable to the whole compositional range of Campi Flegrei products.Moreover, speed data have been used to constrain the ascent velocity of latitic, shoshonitic, and trachytic melts within dikes. Using petrological data and volcanological information (geometrical parameters of the eruptive fissure and depth of magma storage), we estimate a time scale for the ascent of melt from 9. km to 4. km depth (where deep and shallow reservoirs, respectively, are located) in the order of few minutes. Such a rapid ascent should be taken into account for the hazard assessment in the Campi Flegrei area.
KW - Campi Flegrei
KW - Concentric cylinder
KW - Falling sphere
KW - Latites
KW - Micropenetration
KW - Shoshonites
UR - http://www.scopus.com/inward/record.url?scp=80054917604&partnerID=8YFLogxK
U2 - 10.1016/j.chemgeo.2011.08.010
DO - 10.1016/j.chemgeo.2011.08.010
M3 - Article
AN - SCOPUS:80054917604
VL - 290
SP - 50
EP - 59
JO - Chemical geology
JF - Chemical geology
SN - 0009-2541
IS - 1-2
ER -