Details
| Originalsprache | Englisch |
|---|---|
| Seiten (von - bis) | 581-590 |
| Seitenumfang | 10 |
| Fachzeitschrift | Australian Journal of Earth Sciences |
| Jahrgang | 48 |
| Ausgabenummer | 4 |
| Publikationsstatus | Veröffentlicht - 2001 |
Abstract
Dehydration melting of a hornblende-plagiociase mixture of amphibolitic composition was investigated at 1000°C and and at 800 MPa and 1200 MPa. At 1200 MPa the reaction products are garnet, clinopyroxene, melt and relatively Ab-rich plagioclase (An47). At 800 MPa the products are orthopyroxene, clinopyroxene, magnetite, amphibole (pargasite) and An-rich plagioclase (An75). The melts are rich in plagioclase components (especially in Ab) and, when compared to tonalites, relatively poor in silica. The grainsize of the starting materials was ≤5 μm in the 800 MPa and ≤10 μm in the 1200 MPa runs. All run products show unchanged plagloclase cores, which are the remnants of a very sluggish reaction assumed to be controlled by dissolution/precipitation processes at the plagloclase grain boundaries. The results indicate that only local equilibrium could have been obtained in recent investigations on dehydration melting experiments in plagloclase-bearing systems. The results also suggest that plagioclase compositions once formed may persist for a very long time, even in hot magma chambers, if the prevailling water activity is low.
ASJC Scopus Sachgebiete
- Erdkunde und Planetologie (insg.)
- Erdkunde und Planetologie (sonstige)
- Erdkunde und Planetologie (insg.)
- Allgemeine Erdkunde und Planetologie
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in: Australian Journal of Earth Sciences, Jahrgang 48, Nr. 4, 2001, S. 581-590.
Publikation: Beitrag in Fachzeitschrift › Artikel › Forschung › Peer-Review
}
TY - JOUR
T1 - Incomplete reaction of plagioclase in experimental dehydration melting of amphibolite
AU - Johannes, W.
AU - Koepke, J.
PY - 2001
Y1 - 2001
N2 - Dehydration melting of a hornblende-plagiociase mixture of amphibolitic composition was investigated at 1000°C and and at 800 MPa and 1200 MPa. At 1200 MPa the reaction products are garnet, clinopyroxene, melt and relatively Ab-rich plagioclase (An47). At 800 MPa the products are orthopyroxene, clinopyroxene, magnetite, amphibole (pargasite) and An-rich plagioclase (An75). The melts are rich in plagioclase components (especially in Ab) and, when compared to tonalites, relatively poor in silica. The grainsize of the starting materials was ≤5 μm in the 800 MPa and ≤10 μm in the 1200 MPa runs. All run products show unchanged plagloclase cores, which are the remnants of a very sluggish reaction assumed to be controlled by dissolution/precipitation processes at the plagloclase grain boundaries. The results indicate that only local equilibrium could have been obtained in recent investigations on dehydration melting experiments in plagloclase-bearing systems. The results also suggest that plagioclase compositions once formed may persist for a very long time, even in hot magma chambers, if the prevailling water activity is low.
AB - Dehydration melting of a hornblende-plagiociase mixture of amphibolitic composition was investigated at 1000°C and and at 800 MPa and 1200 MPa. At 1200 MPa the reaction products are garnet, clinopyroxene, melt and relatively Ab-rich plagioclase (An47). At 800 MPa the products are orthopyroxene, clinopyroxene, magnetite, amphibole (pargasite) and An-rich plagioclase (An75). The melts are rich in plagioclase components (especially in Ab) and, when compared to tonalites, relatively poor in silica. The grainsize of the starting materials was ≤5 μm in the 800 MPa and ≤10 μm in the 1200 MPa runs. All run products show unchanged plagloclase cores, which are the remnants of a very sluggish reaction assumed to be controlled by dissolution/precipitation processes at the plagloclase grain boundaries. The results indicate that only local equilibrium could have been obtained in recent investigations on dehydration melting experiments in plagloclase-bearing systems. The results also suggest that plagioclase compositions once formed may persist for a very long time, even in hot magma chambers, if the prevailling water activity is low.
KW - Amphibolite
KW - Dehydration melting
KW - Partial melting
KW - Plagioclase
KW - Reaction kinetics
UR - http://www.scopus.com/inward/record.url?scp=0034896130&partnerID=8YFLogxK
U2 - 10.1046/j.1440-0952.2001.00876.x
DO - 10.1046/j.1440-0952.2001.00876.x
M3 - Article
AN - SCOPUS:0034896130
VL - 48
SP - 581
EP - 590
JO - Australian Journal of Earth Sciences
JF - Australian Journal of Earth Sciences
SN - 0812-0099
IS - 4
ER -