| Autor: |
Preuss, Oliver, Marxer, Holger, Ulmer, Sarah, Johannes, Wolf, Nowak, Marcus |
| Zdroj: |
American Mineralogist (De Gruyter); April 2016, Vol. 101 Issue: 4 p859-875, 17p |
| Abstrakt: |
Melt degassing by bubble nucleation and growth is a driving mechanism of magma ascent. Therefore, decompression experiments with hydrous silicate melts were used to investigate the onset and the dynamics of H2O degassing. Nominally H2O undersaturated trachytic Campi Flegrei and phonolitic Vesuvius melts representative for the magma compositions of the Campi Flegrei volcanic system were decompressed at a super-liquidus temperature of 1050 °C from 200 MPa to final pressures (Pfinal) of 100, 75, and 60 MPa using continuous decompression rates of 0.024 and 0.17 MPa/s. Experiments started from either massive glass cylinders or glass powder to demonstrate the infl of the starting material on melt degassing. Glass powder can be used to shorten the equilibration time (teq) prior to decompression for dissolution of H2O in the melt. The decompressed samples were quenched and compared in terms of bubble number density (NV), porosity, and residual H2O content in the melt. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
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