Details
| Original language | English |
|---|---|
| Pages (from-to) | 327-341 |
| Number of pages | 15 |
| Journal | Precambrian research |
| Volume | 124 |
| Issue number | 2-4 |
| Early online date | 6 May 2003 |
| Publication status | Published - 1 Jul 2003 |
Abstract
Crystallisation experiments were performed on two metaluminous A-type granite compositions (AB412 and AB422) from the Wangrah Suite, a representative A-type granite suite from the Lachlan Fold Belt, south eastern Australia. AB412 is more mafic than AB422 and zircon saturation temperatures are 897 and 843°C, respectively. Experiments were performed at 200 MPa, fO2 between NNO and NNO - 1.05 in a temperature range between 700 and 900°C, for various melt H2O contents. Experimental results were compared to the natural phase compositions to constrain the water content of the melt and the phases involved in fractionation processes in the Wangrah Suite. With decreasing temperature, Fe-Ti oxide, orthopyroxene and plagioclase are the first phases to crystallise, followed by biotite. The orthopyroxene stability is mainly restricted to temperatures above 750°C. Hornblende is only stable in the less evolved composition if the water content of the melt is at least 4-5 wt.% H2O. The initial water content in the more mafic melt AB412 was between 2 and 3 wt.% H2O. Although orthopyroxene is not observed in the natural assemblages of the Wangrah Suite, it has influenced the early fractionation of the Wangrah Suite granites. Mass balance calculations show that composition AB422 can be obtained after the crystallisation of 4.7 wt.% iron-rich orthopyroxene plus 8.5 wt.% plagioclase from AB412.
Keywords
- A-type granite, Australia, Crystal fractionation, Experiments, Oxygen fugacity, Water content
ASJC Scopus subject areas
- Earth and Planetary Sciences(all)
- Geology
- Earth and Planetary Sciences(all)
- Geochemistry and Petrology
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In: Precambrian research, Vol. 124, No. 2-4, 01.07.2003, p. 327-341.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Fractionation of metaluminous A-type granites
T2 - An experimental study of the Wangrah Suite, Lachlan Fold Belt, Australia
AU - Klimm, Kevin
AU - Holtz, Francois
AU - Johannes, Wilhelm
AU - King, Penelope L.
N1 - Funding Information: We thank B.W. Chappell for providing the natural samples from the Wangrah Suite and scientific discussion. The technical assistance of O. Dietrich, M. Hahn and J. Koepke as well as the constructive reviews of A.E. Patiño Douce and T.W. Sisson are greatly appreciated. This study was supported by the Deutsche Forschungsgemeinschaft (project no.: Jo64/34-1). Copyright: Copyright 2017 Elsevier B.V., All rights reserved.
PY - 2003/7/1
Y1 - 2003/7/1
N2 - Crystallisation experiments were performed on two metaluminous A-type granite compositions (AB412 and AB422) from the Wangrah Suite, a representative A-type granite suite from the Lachlan Fold Belt, south eastern Australia. AB412 is more mafic than AB422 and zircon saturation temperatures are 897 and 843°C, respectively. Experiments were performed at 200 MPa, fO2 between NNO and NNO - 1.05 in a temperature range between 700 and 900°C, for various melt H2O contents. Experimental results were compared to the natural phase compositions to constrain the water content of the melt and the phases involved in fractionation processes in the Wangrah Suite. With decreasing temperature, Fe-Ti oxide, orthopyroxene and plagioclase are the first phases to crystallise, followed by biotite. The orthopyroxene stability is mainly restricted to temperatures above 750°C. Hornblende is only stable in the less evolved composition if the water content of the melt is at least 4-5 wt.% H2O. The initial water content in the more mafic melt AB412 was between 2 and 3 wt.% H2O. Although orthopyroxene is not observed in the natural assemblages of the Wangrah Suite, it has influenced the early fractionation of the Wangrah Suite granites. Mass balance calculations show that composition AB422 can be obtained after the crystallisation of 4.7 wt.% iron-rich orthopyroxene plus 8.5 wt.% plagioclase from AB412.
AB - Crystallisation experiments were performed on two metaluminous A-type granite compositions (AB412 and AB422) from the Wangrah Suite, a representative A-type granite suite from the Lachlan Fold Belt, south eastern Australia. AB412 is more mafic than AB422 and zircon saturation temperatures are 897 and 843°C, respectively. Experiments were performed at 200 MPa, fO2 between NNO and NNO - 1.05 in a temperature range between 700 and 900°C, for various melt H2O contents. Experimental results were compared to the natural phase compositions to constrain the water content of the melt and the phases involved in fractionation processes in the Wangrah Suite. With decreasing temperature, Fe-Ti oxide, orthopyroxene and plagioclase are the first phases to crystallise, followed by biotite. The orthopyroxene stability is mainly restricted to temperatures above 750°C. Hornblende is only stable in the less evolved composition if the water content of the melt is at least 4-5 wt.% H2O. The initial water content in the more mafic melt AB412 was between 2 and 3 wt.% H2O. Although orthopyroxene is not observed in the natural assemblages of the Wangrah Suite, it has influenced the early fractionation of the Wangrah Suite granites. Mass balance calculations show that composition AB422 can be obtained after the crystallisation of 4.7 wt.% iron-rich orthopyroxene plus 8.5 wt.% plagioclase from AB412.
KW - A-type granite
KW - Australia
KW - Crystal fractionation
KW - Experiments
KW - Oxygen fugacity
KW - Water content
UR - http://www.scopus.com/inward/record.url?scp=0038810243&partnerID=8YFLogxK
U2 - 10.1016/S0301-9268(03)00092-5
DO - 10.1016/S0301-9268(03)00092-5
M3 - Article
AN - SCOPUS:0038810243
VL - 124
SP - 327
EP - 341
JO - Precambrian research
JF - Precambrian research
SN - 0301-9268
IS - 2-4
ER -