Details
| Originalsprache | Englisch |
|---|---|
| Aufsatznummer | egs035 |
| Seiten (von - bis) | 1837-1866 |
| Seitenumfang | 30 |
| Fachzeitschrift | Journal of Petrology |
| Jahrgang | 53 |
| Ausgabenummer | 9 |
| Publikationsstatus | Veröffentlicht - 3 Juli 2012 |
Abstract
The phase relations have been investigated experimentally at 200 and 500 MPa as a function of water activity for one of the least evolved (Indian Batt Rhyolite) and of a more evolved rhyolite composition (Cougar Point Tuff XV) from the 12·8-8·1 Ma Bruneau-Jarbidge eruptive center of the Yellowstone hotspot. Particular priority was given to accurate determination of the water content of the quenched glasses using infrared spectroscopic techniques. Comparison of the composition of natural and experimentally synthesized phases confirms that high temperatures (>900°C) and extremely low melt water contents (<1·5 wt % H. 2O) are required to reproduce the natural mineral assemblages. In melts containing ∼0·5-1·5 wt % H. 2O, the liquidus phase is clinopyroxene (excluding Fe-Ti oxides, which are strongly dependent on fO. 2), and the liquidus temperature of the more evolved Cougar Point Tuff sample (BJR; ∼940-1000°C) is at least 30°C lower than that of the Indian Batt Rhyolite lava sample (IBR2; 970-1030°C). For the composition BJR, the comparison of the compositions of the natural and experimental glasses indicates a pre-eruptive temperature of at least 900°C. The composition of clinopyroxene and pigeonite pairs can be reproduced only for water contents below 1·5 wt % H. 2O at 900°C, or lower water contents if the temperature is higher. For the composition IBR2, a minimum temperature of 920°C is necessary to reproduce the main phases at 200 and 500 MPa. At 200 MPa, the pre-eruptive water content of the melt is constrained in the range 0·7-1·3 wt % at 950°C and 0·3-1·0 wt % at 1000°C. At 500 MPa, the pre-eruptive temperatures are slightly higher (by ∼30-50°C) for the same ranges of water concentration. The experimental results are used to explore possible proxies to constrain the depth of magma storage. The crystallization sequence of tectosilicates is strongly dependent on pressure between 200 and 500 MPa. In addition, the normative Qtz-Ab-Or contents of glasses quenched from melts coexisting with quartz, sanidine and plagioclase depend on pressure and melt water content, assuming that the normative Qtz and Ab/Or content of such melts is mainly dependent on pressure and water activity, respectively. The combination of results from the phase equilibria and from the composition of glasses indicates that the depth of magma storage for the IBR2 and BJR compositions may be in the range 300-400 MPa (∼≤13 km) and 200-300 MPa (∼≤10 km), respectively.
ASJC Scopus Sachgebiete
- Erdkunde und Planetologie (insg.)
- Geophysik
- Erdkunde und Planetologie (insg.)
- Geochemie und Petrologie
Zitieren
- Standard
- Harvard
- Apa
- Vancouver
- BibTex
- RIS
in: Journal of Petrology, Jahrgang 53, Nr. 9, egs035, 03.07.2012, S. 1837-1866.
Publikation: Beitrag in Fachzeitschrift › Artikel › Forschung › Peer-Review
}
TY - JOUR
T1 - High-temperature, low-H 2O silicic magmas of the yellowstone hotspot
T2 - An experimental study of rhyolite from the Bruneau-Jarbidge eruptive center, Central Snake River Plain, USA
AU - Almeev, Renat R.
AU - Bolte, Torsten
AU - Nash, Barbara P.
AU - Holtz, François
AU - Erdmann, Martin
AU - Cathey, Henrietta E.
N1 - Funding Information: This study was funded by the German Research Foundation (DFG, project Ho 1337/17 and Ho 1337/22). B. Nash very much appreciates the award of a Mercator Professorship and support from the German Research Foundation during her sabbatical at the Leibniz University of Hannover, as well as partial support from the National Science Foundation, grant EAR0510327. Copyright: Copyright 2012 Elsevier B.V., All rights reserved.
PY - 2012/7/3
Y1 - 2012/7/3
N2 - The phase relations have been investigated experimentally at 200 and 500 MPa as a function of water activity for one of the least evolved (Indian Batt Rhyolite) and of a more evolved rhyolite composition (Cougar Point Tuff XV) from the 12·8-8·1 Ma Bruneau-Jarbidge eruptive center of the Yellowstone hotspot. Particular priority was given to accurate determination of the water content of the quenched glasses using infrared spectroscopic techniques. Comparison of the composition of natural and experimentally synthesized phases confirms that high temperatures (>900°C) and extremely low melt water contents (<1·5 wt % H. 2O) are required to reproduce the natural mineral assemblages. In melts containing ∼0·5-1·5 wt % H. 2O, the liquidus phase is clinopyroxene (excluding Fe-Ti oxides, which are strongly dependent on fO. 2), and the liquidus temperature of the more evolved Cougar Point Tuff sample (BJR; ∼940-1000°C) is at least 30°C lower than that of the Indian Batt Rhyolite lava sample (IBR2; 970-1030°C). For the composition BJR, the comparison of the compositions of the natural and experimental glasses indicates a pre-eruptive temperature of at least 900°C. The composition of clinopyroxene and pigeonite pairs can be reproduced only for water contents below 1·5 wt % H. 2O at 900°C, or lower water contents if the temperature is higher. For the composition IBR2, a minimum temperature of 920°C is necessary to reproduce the main phases at 200 and 500 MPa. At 200 MPa, the pre-eruptive water content of the melt is constrained in the range 0·7-1·3 wt % at 950°C and 0·3-1·0 wt % at 1000°C. At 500 MPa, the pre-eruptive temperatures are slightly higher (by ∼30-50°C) for the same ranges of water concentration. The experimental results are used to explore possible proxies to constrain the depth of magma storage. The crystallization sequence of tectosilicates is strongly dependent on pressure between 200 and 500 MPa. In addition, the normative Qtz-Ab-Or contents of glasses quenched from melts coexisting with quartz, sanidine and plagioclase depend on pressure and melt water content, assuming that the normative Qtz and Ab/Or content of such melts is mainly dependent on pressure and water activity, respectively. The combination of results from the phase equilibria and from the composition of glasses indicates that the depth of magma storage for the IBR2 and BJR compositions may be in the range 300-400 MPa (∼≤13 km) and 200-300 MPa (∼≤10 km), respectively.
AB - The phase relations have been investigated experimentally at 200 and 500 MPa as a function of water activity for one of the least evolved (Indian Batt Rhyolite) and of a more evolved rhyolite composition (Cougar Point Tuff XV) from the 12·8-8·1 Ma Bruneau-Jarbidge eruptive center of the Yellowstone hotspot. Particular priority was given to accurate determination of the water content of the quenched glasses using infrared spectroscopic techniques. Comparison of the composition of natural and experimentally synthesized phases confirms that high temperatures (>900°C) and extremely low melt water contents (<1·5 wt % H. 2O) are required to reproduce the natural mineral assemblages. In melts containing ∼0·5-1·5 wt % H. 2O, the liquidus phase is clinopyroxene (excluding Fe-Ti oxides, which are strongly dependent on fO. 2), and the liquidus temperature of the more evolved Cougar Point Tuff sample (BJR; ∼940-1000°C) is at least 30°C lower than that of the Indian Batt Rhyolite lava sample (IBR2; 970-1030°C). For the composition BJR, the comparison of the compositions of the natural and experimental glasses indicates a pre-eruptive temperature of at least 900°C. The composition of clinopyroxene and pigeonite pairs can be reproduced only for water contents below 1·5 wt % H. 2O at 900°C, or lower water contents if the temperature is higher. For the composition IBR2, a minimum temperature of 920°C is necessary to reproduce the main phases at 200 and 500 MPa. At 200 MPa, the pre-eruptive water content of the melt is constrained in the range 0·7-1·3 wt % at 950°C and 0·3-1·0 wt % at 1000°C. At 500 MPa, the pre-eruptive temperatures are slightly higher (by ∼30-50°C) for the same ranges of water concentration. The experimental results are used to explore possible proxies to constrain the depth of magma storage. The crystallization sequence of tectosilicates is strongly dependent on pressure between 200 and 500 MPa. In addition, the normative Qtz-Ab-Or contents of glasses quenched from melts coexisting with quartz, sanidine and plagioclase depend on pressure and melt water content, assuming that the normative Qtz and Ab/Or content of such melts is mainly dependent on pressure and water activity, respectively. The combination of results from the phase equilibria and from the composition of glasses indicates that the depth of magma storage for the IBR2 and BJR compositions may be in the range 300-400 MPa (∼≤13 km) and 200-300 MPa (∼≤10 km), respectively.
KW - Bruneau-Jarbidge
KW - Crystallization experiments
KW - Phase equilibria
KW - Rhyolite
KW - Snake River Plain
KW - Yellowstone hotspot
UR - http://www.scopus.com/inward/record.url?scp=84865577284&partnerID=8YFLogxK
U2 - 10.1093/petrology/egs035
DO - 10.1093/petrology/egs035
M3 - Article
AN - SCOPUS:84865577284
VL - 53
SP - 1837
EP - 1866
JO - Journal of Petrology
JF - Journal of Petrology
SN - 0022-3530
IS - 9
M1 - egs035
ER -