Phase relations in the system K 2 O-FeO-Al 2 O 3 -SiO 2 at 1 atmosphere with special emphasis on low temperature liquid immiscibility

Visser, W.; Groos, A. F. Koster van

doi:10.2475/ajs.279.1.70

Cited by 41 publications

(18 citation statements)

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“…Walker et al (1972) reported rim-crystallization of MoO 2 at 0.1 MPa, the fO 2 of their run being then on the Mo-MoO 2 buffer. Visser and Koster van Groos (1979a) calculated that this buffer is in the wü stite stability field, producing fO 2 slightly above the IW buffer at temperatures similar to this study. In our experiments, we crystallized a stoichiometric phase FeMo 2 O 5 , to our knowledge not described in the literature.…”

Section: Methodssupporting

confidence: 79%

“…2a): a hightemperature field along the Fe 2 SiO 4 -SiO 2 join (above 1,695°C) and a low-temperature immiscibility field discovered by Roedder (1951). This latter immiscibility field has been well constrained by Roedder (1978), Visser and Koster van Groos (1979a) and Freestone and Powell (1983) at 0.1 MPa and by Visser and Koster van Groos (1979b) at higher pressures. It occurs along the fayalite-tridymite cotectic, separating a FeO-rich melt (corresponding to a simplified ferro-basalt) from a SiO 2 -rich melt (ferro-dacitic in composition, Fig.…”

Section: Generalmentioning

confidence: 75%

“…At 0.1 MPa, the critical temperature of the miscibility gap is near 1,235°C, while the lowest temperature where two melts coexist is near 1,110°C. The high and low-temperature immiscibility fields are considered to be the stable parts of a common two-melt field partially below the cristobalite-trydimite liquidus (Visser and Koster van Groos 1979a).…”

Section: Generalmentioning

confidence: 99%

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Experiments on silicate melt immiscibility in the system Fe2SiO4–KAlSi3O8–SiO2–CaO–MgO–TiO2–P2O5 and implications for natural magmas

Bogaerts

Schmidt

2006

Contrib Mineral Petrol

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The effect of CaO and MgO, with or without TiO 2 and P 2 O 5 , on the two-melt field in the simplified system Fe 2 SiO 4 -KAlSi 3 O 8 -SiO 2 has been experimentally determined at 1,050°-1,240°C, 400 MPa. Despite the suppressing effect of MgO, CaO, and pressure on silicate melt immiscibility, our experiments show that this process is still viable at mid-crustal pressures when small amounts (0.6-2.0 wt%) of P 2 O 5 and TiO 2 are present. Our data stress that the major element partition coefficients between the two melts are highly correlated with the degree of polymerisation (nbo/t) of the SiO 2 -rich melt, whatever temperature, pressure, or exact composition. Experimental immiscible melt compositions in natural systems at 0.1 MPa from the literature (lunar and tholeiitic basalts) plot on similar but distinct curves compared to the simplified system. These relations between melt polymerisation and partition coefficients, which hold for a large range of compositions and fO 2 , are extended to various volcanic and plutonic rocks. This analysis strengthens the proposal that silicate melt immiscibility can be important in volcanic rocks of various compositions (from tholeiitic basalts to lamprophyres). However, the majority of proposed immiscible compositions in plutonic rocks are at least not coexisting melts, but may have suffered accumulation of early crystallized minerals.

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Section: Methodssupporting

confidence: 79%

Section: Generalmentioning

confidence: 75%

Section: Generalmentioning

confidence: 99%

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Experiments on silicate melt immiscibility in the system Fe2SiO4–KAlSi3O8–SiO2–CaO–MgO–TiO2–P2O5 and implications for natural magmas

Bogaerts

Schmidt

2006

Contrib Mineral Petrol

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“…This observation provides further evidence in favor of the idea that the immiscibility fi eld closes at low temperature, behavior perfectly consistent with phase relations in the system K 2 O-FeO-Al 2 O 3 -SiO 2 (Visser and Koster van Groos, 1979), although we know of no data to assess whether this is true in complex natural systems. Closing of the miscibility gap at low temperature would have the consequence that liquid unmixing would have no bearing on the geochemical signature of residual granitic compositions, but would nevertheless be responsible for the absence of intermediate liquid compositions, i.e., the Daly gap.…”

Section: Discussionmentioning

confidence: 70%

Large-scale silicate liquid immiscibility during differentiation of tholeiitic basalt to granite and the origin of the Daly gap

Charlier

Namur

Toplis

et al. 2011

Geology

153

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“…Experiments on liquid immiscibility have mainly been performed on simplified systems (e.g., Roedder 1978;Bogaerts and Schmidt 2006). Consequently, even though phase relations in the system K 2 O-FeO-Al 2 O 3 -SiO 2 are well known (Roedder 1978;Visser and Koster van Groos 1979a;Freestone and Powell 1983) and the effects of other elements such as P 2 O 5 , TiO 2 , CaO, and MgO in reducing or expanding the immiscibility field have been experimentally identified (Watson 1976;Visser and Koster van Groos 1979b;Naslund 1983;Bogaerts and Schmidt 2006), direct application of these results to complex natural basaltic systems is not straightforward. In this study, we define the compositional space for the development of immiscibility during tholeiitic basalt differentiation.…”

Section: Introductionmentioning

confidence: 99%

Experiments on liquid immiscibility along tholeiitic liquid lines of descent

Charlier

Grove

2012

Contrib Mineral Petrol

204

165

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Crystallization experiments have been conducted on compositions along tholeiitic liquid lines of descent to define the compositional space for the development of silicate liquid immiscibility. Starting materials have 46-56 wt% SiO 2 , 11.7-17.7 wt% FeO tot , and Mgnumber between 0.29 and 0.36. These melts fall on the basaltic trends relevant for Mull, Iceland, Snake River Plain lavas and for the Sept Iles layered intrusion, where large-scale liquid immiscibility has been recognized. At one atmosphere under anhydrous conditions, immiscibility develops below 1,000-1,020°C in all of these compositionally diverse lavas. Extreme iron enrichment is not necessary; immiscibility also develops during iron depletion and silica enrichment. Variations in melt composition control the development of silicate liquid immiscibility along the tholeiitic trend. Elevation of Na 2 O ? K 2 O ? P 2 O 5 ? TiO 2 promotes the development of two immiscible liquids. Increasing melt CaO and Al 2 O 3 stabilizes a singleliquid field. New data and published phase equilibria show that anhydrous, low-pressure fractional crystallization is the most favorable condition for unmixing during differentiation. Pressure inhibits immiscibility because it expands the stability field of high-Ca clinopyroxene, which reduces the proportion of plagioclase in the crystallizing assemblage, thus enhancing early iron depletion. Magma mixing between primitive basalt and Fe-Ti-P-rich ferrobasalts can serve to elevate phosphorous and alkali contents and thereby promote unmixing. Water might decrease the temperature and size of the two-liquid field, potentially shifting the binodal (solvus) below the liquidus, leading the system to evolve as a single-melt phase.

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Phase relations in the system K 2 O-FeO-Al 2 O 3 -SiO 2 at 1 atmosphere with special emphasis on low temperature liquid immiscibility

Cited by 41 publications

References 0 publications

Experiments on silicate melt immiscibility in the system Fe2SiO4–KAlSi3O8–SiO2–CaO–MgO–TiO2–P2O5 and implications for natural magmas

Experiments on silicate melt immiscibility in the system Fe2SiO4–KAlSi3O8–SiO2–CaO–MgO–TiO2–P2O5 and implications for natural magmas

Large-scale silicate liquid immiscibility during differentiation of tholeiitic basalt to granite and the origin of the Daly gap

Experiments on liquid immiscibility along tholeiitic liquid lines of descent

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