Details
| Original language | English |
|---|---|
| Pages (from-to) | 659-672 |
| Number of pages | 14 |
| Journal | Contributions to Mineralogy and Petrology |
| Volume | 145 |
| Issue number | 6 |
| Early online date | 5 Jul 2003 |
| Publication status | Published - Sept 2003 |
Abstract
Phase relations of a phonolite (K1) and a tephri-phonolite (K2) from the Upper Miocene lavas in the Southeast Province of the Kerguelen Archipelago have been investigated in the P/T range 100-500 MPa and 700 900 °C at two fO2 conditions (∼NNO and ∼NNO + 2.3 to clarify the differentiation and pre-eruptive conditions of these magmas. Crystallization experiments were performed in cold seal pressure vessels (CSPV) and internally heated pressure vessels (IHPV) at various XH2O, under reducing (log fO2 ∼ NNO) and oxidizing conditions (log fO2 ∼ NNO + 2.3). Under reducing conditions, the resulting phase assemblage for K1 was: titanomagnetite, nepheline, alkali feldspar, clinopyroxene and biotite; under oxidizing conditions, the assemblage was: magnetite, plagioclase, alkali feldspar, nepheline. titanite (minerals given in the order of appearance with decreasing T at 200 MPa for 4 wt% water in the melt). It is emphasized that an effect of fO2 on the phase stability of feldspars and feldspathoides was observed. Comparison of the natural and experimental phase assemblages shows that the pre-eruptive conditions for K1 must have been in the log fO2 range ΔNN0 + 1-ΔNN0 + 2, at pressures above 200-250 MPa. Assuming a temperature of 800 °C, the water content of the melt is constrained to be between 4 and 6 wt% H2O. The pre-eruptive fO2 conditions for the less evolved sample K2 are more oxidizing with log fO2 close to ΔNNO + 2.3. The experimental results show that the enrichment of alkalis in residual melts during differentiation of tephri-phonolites is enhanced at high fO2.
ASJC Scopus subject areas
- Earth and Planetary Sciences(all)
- Geophysics
- Earth and Planetary Sciences(all)
- Geochemistry and Petrology
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In: Contributions to Mineralogy and Petrology, Vol. 145, No. 6, 09.2003, p. 659-672.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Experimental constraints on the storage conditions of phonolites from the Kerguelen Archipelago
AU - Freise, Marcus
AU - Holtz, Francois
AU - Koepke, Jürgen
AU - Scoates, James
AU - Leyrit, Hervé
N1 - Funding Information: Acknowledgments This research was performed in the framework of the ODP ‘‘Schwerpunktprogramm’’ supported by the German Science Foundation (DFG). The ODP is sponsored by the US National Science Foundation (NSF) and participating countries under management of Joint Oceanographic Institutions (JOI), Inc. The samples LVLK 81, LVLK 90 and LVLK 93 were collected on the Kerguelen Archipelago during the austral summer of 1988 by H. Leyrit, O. Verdier and D. Weis and during the following winter by H. Leyrit. We thank Dominique Weis for help in selecting the appropriate samples for the experimental study. We thank O. Dietrich for preparing the samples and W. Hurkuck and B. Aichinger for technical assistance. Finally, many thanks are due to B. Scaillet and an anonymous reviewer for their careful reviews and helpful suggestions. Copyright: Copyright 2008 Elsevier B.V., All rights reserved.
PY - 2003/9
Y1 - 2003/9
N2 - Phase relations of a phonolite (K1) and a tephri-phonolite (K2) from the Upper Miocene lavas in the Southeast Province of the Kerguelen Archipelago have been investigated in the P/T range 100-500 MPa and 700 900 °C at two fO2 conditions (∼NNO and ∼NNO + 2.3 to clarify the differentiation and pre-eruptive conditions of these magmas. Crystallization experiments were performed in cold seal pressure vessels (CSPV) and internally heated pressure vessels (IHPV) at various XH2O, under reducing (log fO2 ∼ NNO) and oxidizing conditions (log fO2 ∼ NNO + 2.3). Under reducing conditions, the resulting phase assemblage for K1 was: titanomagnetite, nepheline, alkali feldspar, clinopyroxene and biotite; under oxidizing conditions, the assemblage was: magnetite, plagioclase, alkali feldspar, nepheline. titanite (minerals given in the order of appearance with decreasing T at 200 MPa for 4 wt% water in the melt). It is emphasized that an effect of fO2 on the phase stability of feldspars and feldspathoides was observed. Comparison of the natural and experimental phase assemblages shows that the pre-eruptive conditions for K1 must have been in the log fO2 range ΔNN0 + 1-ΔNN0 + 2, at pressures above 200-250 MPa. Assuming a temperature of 800 °C, the water content of the melt is constrained to be between 4 and 6 wt% H2O. The pre-eruptive fO2 conditions for the less evolved sample K2 are more oxidizing with log fO2 close to ΔNNO + 2.3. The experimental results show that the enrichment of alkalis in residual melts during differentiation of tephri-phonolites is enhanced at high fO2.
AB - Phase relations of a phonolite (K1) and a tephri-phonolite (K2) from the Upper Miocene lavas in the Southeast Province of the Kerguelen Archipelago have been investigated in the P/T range 100-500 MPa and 700 900 °C at two fO2 conditions (∼NNO and ∼NNO + 2.3 to clarify the differentiation and pre-eruptive conditions of these magmas. Crystallization experiments were performed in cold seal pressure vessels (CSPV) and internally heated pressure vessels (IHPV) at various XH2O, under reducing (log fO2 ∼ NNO) and oxidizing conditions (log fO2 ∼ NNO + 2.3). Under reducing conditions, the resulting phase assemblage for K1 was: titanomagnetite, nepheline, alkali feldspar, clinopyroxene and biotite; under oxidizing conditions, the assemblage was: magnetite, plagioclase, alkali feldspar, nepheline. titanite (minerals given in the order of appearance with decreasing T at 200 MPa for 4 wt% water in the melt). It is emphasized that an effect of fO2 on the phase stability of feldspars and feldspathoides was observed. Comparison of the natural and experimental phase assemblages shows that the pre-eruptive conditions for K1 must have been in the log fO2 range ΔNN0 + 1-ΔNN0 + 2, at pressures above 200-250 MPa. Assuming a temperature of 800 °C, the water content of the melt is constrained to be between 4 and 6 wt% H2O. The pre-eruptive fO2 conditions for the less evolved sample K2 are more oxidizing with log fO2 close to ΔNNO + 2.3. The experimental results show that the enrichment of alkalis in residual melts during differentiation of tephri-phonolites is enhanced at high fO2.
UR - http://www.scopus.com/inward/record.url?scp=0141888850&partnerID=8YFLogxK
U2 - 10.1007/s00410-003-0453-2
DO - 10.1007/s00410-003-0453-2
M3 - Article
AN - SCOPUS:0141888850
VL - 145
SP - 659
EP - 672
JO - Contributions to Mineralogy and Petrology
JF - Contributions to Mineralogy and Petrology
SN - 0010-7999
IS - 6
ER -