- Split View
-
Views
-
Cite
Cite
T.-C. LIU, D. C. PRESNALL, Liquidus Phase Relations in the System CaO–MgO–Al2O3–SiO2 at 2·0 GPa: Applications to Basalt Fractionation, Eclogites, and Igneous Sapphirine, Journal of Petrology, Volume 41, Issue 1, January 2000, Pages 3–20, https://doi.org/10.1093/petrology/41.1.3
- Share Icon Share
Abstract
To model magmatic crystallization processes for mafic to intermediate compositions at high pressure, liquidus phase relations in the forsterite–anorthite–diopside–silica (FADS) tetrahedron within the CaO–MgO–Al2O3–SiO2 system have been determined at 2·0 GPa. Compositions of five liquidus invariant points have been determined and the approximate compositions of five others have been inferred. These involve primary phase volumes for forsterite (fo), enstatite (en), diopside (di), high quartz (qz), spinel (sp), sapphirine (sa), garnet (gt), anorthite (an), and corundum (cor). The determined (with wt % coefficients) and inferred reactions (without coefficients) that define each isobaric invariant point are as follows:
23 en + 68 di + 9 sp = 84 liq + 16 fo
37 di + 63 sa = 47 liq + 40 sp + 13 en
100 gt = 21 liq + 27 sa + 55 en + 18 di
1 di + 59 en + 41 an = 43 liq + 57 gt
18 di + 21 qz + 15 en + 47 an = 100 liq
di + an + gt = liq + sa
an + gt = liq + sa + en
sa + an + di = liq + sp
sa + an = liq + cor + sp
di + cor = liq + an + sp.
These phase relations provide a diverse range of constraints on igneous processes at pressures near 2 GPa. They show that fractional crystallization of a model basalt gives a residual liquid strongly enriched in SiO2, strongly depleted in MgO, and mildly enriched in Al2O3. Such a trend is consistent with the calc-alkaline fractionation trend observed at subduction zones, but is in disagreement with suggestions that fractionation of tholeiitic basalt in this pressure range yields an alkalic basalt. Both trends may occur for natural basalts depending on the Na2O content of the parental magma. Also, the data show that the minimum pressure for the formation of cumulate eclogites and garnet pyroxenites is about 1·8–1·9 GPa. The lower limit of pressure at which sapphirine can crystallize from a liquid in the FADS tetrahedron is estimated to be 1·1–1·5 GPa and the upper limit is >3 GPa. Sapphirine crystallizes from magmas intermediate in composition between basalt and andesite. Probable igneous sapphirine in mafic associations is rare, but it occurs as part of a pyroxenite xenolith from Delegate, Australia, that we suggest is a cumulate assemblage and in a sapphirine norite at Wilson Lake, Labrador, Canada.
INTRODUCTION
Liquidus phase relations in the system CaO–MgO–Al2O3–SiO2 (CMAS) have been used extensively to model the generation and crystallization of basaltic magmas and the crystallization behavior of magma oceans. The portion of this system most relevant to the petrogenesis of mafic and ultramafic magmas is the tetrahedron forsterite–Ca Tschermak’s molecule–diopside–silica, which is a simplified analog of the basalt tetrahedron of Yoder & Tilley (1962). The smaller tetrahedral volume, forsterite–anorthite–diopside–silica (FADS), is an approximation of the tholeiitic portion of the basalt tetrahedron and various parts of this tetrahedron have been the object of many experimental investigations at high pressures. These studies have led to a reasonably good understanding of the broad outline of liquidus phase relations in the interior of the FADS tetrahedron at 1 atm (Presnall et al., 1979; Longhi, 1987) and 3·0 GPa (Milholland & Presnall, 1998), but liquidus phase boundaries at 2·0 GPa have not been determined except for the liquid composition at the invariant point, forsterite + enstatite + diopside + spinel + liquid (Presnall et al., 1979; Walter & Presnall, 1994).
We have determined or inferred the locations of liquidus invariant points and univariant curves throughout the entire tetrahedron. The phase relations are complex, mainly because of the unexpected discovery of primary phase volumes for sapphirine and garnet. These data provide a basis for discussing in general terms the fractional crystallization of model basaltic magmas at 2·0 GPa. The discussion is necessarily limited to the four oxides present in the system, but these oxides make up about 85% of the composition of typical tholeiitic basalts. Sapphirine has been considered to be an almost exclusively metamorphic mineral, but we present evidence here that it would be expected to crystallize from ordinary magmas of intermediate composition between basalt and andesite at high pressures. Also, we use our data to place an approximate lower limit on the pressure at which eclogite and garnet pyroxenite cumulates can form.
EXPERIMENTAL METHODS
The starting mixtures (Table 1) are those used by Presnall (1976), Presnall et al. (1979),Sen & Presnall (1984) and Liu & Presnall (1990), plus several new mixtures prepared according to the procedures described by Presnall (1966) and Presnall et al. (1972). Experiments were performed with piston–cylinder presses (Boyd & England, 1960), and the experimental techniques are the same as described by Liu & Presnall (1990).
Mixture | Di | An | Fo | En | Qz |
60An40En | 60·00 | 40·00 | |||
80An20En | 80·00 | 20·00 | |||
AFQ-20 | 55·00 | 20·00 | 25·00 | ||
AFQ-21 | 53·00 | 38·00 | 9·00 | ||
AFQ-22 | 50·00 | 42·00 | 8·00 | ||
AFQ-23 | 65·00 | 8·00 | 27·00 | ||
AFQ-25 | 72·00 | 19·00 | 9·00 | ||
AFQ-26 | 70·00 | 4·00 | 26·00 | ||
AFQ-28 | 72·00 | 14·00 | 14·00 | ||
AED-52 | 15·00 | 65·00 | 20·00 | ||
AED-54 | 15·00 | 55·00 | 30·00 | ||
GS-0 | 55·00 | 35·00 | 10·00 | ||
GS-6 | 60·00 | 12·00 | 28·00 | ||
GS-8 | 62·00 | 22·00 | 16·00 | ||
GS-11 | 64·00 | 23·00 | 13·00 | ||
CMAS-4 | 16·56 | 52·44 | 22·83 | 8·17 | |
CMAS-5 | 14·86 | 49·82 | 28·19 | 7·13 | |
CMAS-7 | 21·00 | 48·00 | 31·00 | ||
CMAS-10 | 12·03 | 55·79 | 17·91 | 14·27 | |
CMAS-11 | 27·48 | 42·64 | 12·30 | 17·58 | |
CMAS-12 | 6·00 | 58·00 | 12·00 | 24·00 | |
CMAS-13 | 20·89 | 47·52 | 26·70 | 4·89 | |
CMAS-14 | 12·69 | 67·65 | 10·09 | 9·57 | |
CMAS-15 | 7·39 | 59·76 | 17·67 | 15·18 | |
CMAS-16 | 5·61 | 57·38 | 19·13 | 17·88 | |
CMAS-17 | 15·02 | 49·72 | 29·75 | 5·51 | |
CMAS-18 | 9·99 | 58·51 | 24·75 | 6·75 | |
CMAS-19 | 17·04 | 62·65 | 11·60 | 8·71 | |
CMAS-20 | 17·89 | 48·66 | 27·44 | 6·01 | |
CMAS-21 | 7·00 | 63·39 | 16·60 | 13·01 | |
CMAS-22 | 5·21 | 61·48 | 18·10 | 15·21 |
Mixture | Di | An | Fo | En | Qz |
60An40En | 60·00 | 40·00 | |||
80An20En | 80·00 | 20·00 | |||
AFQ-20 | 55·00 | 20·00 | 25·00 | ||
AFQ-21 | 53·00 | 38·00 | 9·00 | ||
AFQ-22 | 50·00 | 42·00 | 8·00 | ||
AFQ-23 | 65·00 | 8·00 | 27·00 | ||
AFQ-25 | 72·00 | 19·00 | 9·00 | ||
AFQ-26 | 70·00 | 4·00 | 26·00 | ||
AFQ-28 | 72·00 | 14·00 | 14·00 | ||
AED-52 | 15·00 | 65·00 | 20·00 | ||
AED-54 | 15·00 | 55·00 | 30·00 | ||
GS-0 | 55·00 | 35·00 | 10·00 | ||
GS-6 | 60·00 | 12·00 | 28·00 | ||
GS-8 | 62·00 | 22·00 | 16·00 | ||
GS-11 | 64·00 | 23·00 | 13·00 | ||
CMAS-4 | 16·56 | 52·44 | 22·83 | 8·17 | |
CMAS-5 | 14·86 | 49·82 | 28·19 | 7·13 | |
CMAS-7 | 21·00 | 48·00 | 31·00 | ||
CMAS-10 | 12·03 | 55·79 | 17·91 | 14·27 | |
CMAS-11 | 27·48 | 42·64 | 12·30 | 17·58 | |
CMAS-12 | 6·00 | 58·00 | 12·00 | 24·00 | |
CMAS-13 | 20·89 | 47·52 | 26·70 | 4·89 | |
CMAS-14 | 12·69 | 67·65 | 10·09 | 9·57 | |
CMAS-15 | 7·39 | 59·76 | 17·67 | 15·18 | |
CMAS-16 | 5·61 | 57·38 | 19·13 | 17·88 | |
CMAS-17 | 15·02 | 49·72 | 29·75 | 5·51 | |
CMAS-18 | 9·99 | 58·51 | 24·75 | 6·75 | |
CMAS-19 | 17·04 | 62·65 | 11·60 | 8·71 | |
CMAS-20 | 17·89 | 48·66 | 27·44 | 6·01 | |
CMAS-21 | 7·00 | 63·39 | 16·60 | 13·01 | |
CMAS-22 | 5·21 | 61·48 | 18·10 | 15·21 |
Abbreviations: Di, CaMgSi2O6; An, CaAl2Si2O8; Fo, Mg2SiO4; En, MgSiO3; Qz, SiO2.
Mixture | Di | An | Fo | En | Qz |
60An40En | 60·00 | 40·00 | |||
80An20En | 80·00 | 20·00 | |||
AFQ-20 | 55·00 | 20·00 | 25·00 | ||
AFQ-21 | 53·00 | 38·00 | 9·00 | ||
AFQ-22 | 50·00 | 42·00 | 8·00 | ||
AFQ-23 | 65·00 | 8·00 | 27·00 | ||
AFQ-25 | 72·00 | 19·00 | 9·00 | ||
AFQ-26 | 70·00 | 4·00 | 26·00 | ||
AFQ-28 | 72·00 | 14·00 | 14·00 | ||
AED-52 | 15·00 | 65·00 | 20·00 | ||
AED-54 | 15·00 | 55·00 | 30·00 | ||
GS-0 | 55·00 | 35·00 | 10·00 | ||
GS-6 | 60·00 | 12·00 | 28·00 | ||
GS-8 | 62·00 | 22·00 | 16·00 | ||
GS-11 | 64·00 | 23·00 | 13·00 | ||
CMAS-4 | 16·56 | 52·44 | 22·83 | 8·17 | |
CMAS-5 | 14·86 | 49·82 | 28·19 | 7·13 | |
CMAS-7 | 21·00 | 48·00 | 31·00 | ||
CMAS-10 | 12·03 | 55·79 | 17·91 | 14·27 | |
CMAS-11 | 27·48 | 42·64 | 12·30 | 17·58 | |
CMAS-12 | 6·00 | 58·00 | 12·00 | 24·00 | |
CMAS-13 | 20·89 | 47·52 | 26·70 | 4·89 | |
CMAS-14 | 12·69 | 67·65 | 10·09 | 9·57 | |
CMAS-15 | 7·39 | 59·76 | 17·67 | 15·18 | |
CMAS-16 | 5·61 | 57·38 | 19·13 | 17·88 | |
CMAS-17 | 15·02 | 49·72 | 29·75 | 5·51 | |
CMAS-18 | 9·99 | 58·51 | 24·75 | 6·75 | |
CMAS-19 | 17·04 | 62·65 | 11·60 | 8·71 | |
CMAS-20 | 17·89 | 48·66 | 27·44 | 6·01 | |
CMAS-21 | 7·00 | 63·39 | 16·60 | 13·01 | |
CMAS-22 | 5·21 | 61·48 | 18·10 | 15·21 |
Mixture | Di | An | Fo | En | Qz |
60An40En | 60·00 | 40·00 | |||
80An20En | 80·00 | 20·00 | |||
AFQ-20 | 55·00 | 20·00 | 25·00 | ||
AFQ-21 | 53·00 | 38·00 | 9·00 | ||
AFQ-22 | 50·00 | 42·00 | 8·00 | ||
AFQ-23 | 65·00 | 8·00 | 27·00 | ||
AFQ-25 | 72·00 | 19·00 | 9·00 | ||
AFQ-26 | 70·00 | 4·00 | 26·00 | ||
AFQ-28 | 72·00 | 14·00 | 14·00 | ||
AED-52 | 15·00 | 65·00 | 20·00 | ||
AED-54 | 15·00 | 55·00 | 30·00 | ||
GS-0 | 55·00 | 35·00 | 10·00 | ||
GS-6 | 60·00 | 12·00 | 28·00 | ||
GS-8 | 62·00 | 22·00 | 16·00 | ||
GS-11 | 64·00 | 23·00 | 13·00 | ||
CMAS-4 | 16·56 | 52·44 | 22·83 | 8·17 | |
CMAS-5 | 14·86 | 49·82 | 28·19 | 7·13 | |
CMAS-7 | 21·00 | 48·00 | 31·00 | ||
CMAS-10 | 12·03 | 55·79 | 17·91 | 14·27 | |
CMAS-11 | 27·48 | 42·64 | 12·30 | 17·58 | |
CMAS-12 | 6·00 | 58·00 | 12·00 | 24·00 | |
CMAS-13 | 20·89 | 47·52 | 26·70 | 4·89 | |
CMAS-14 | 12·69 | 67·65 | 10·09 | 9·57 | |
CMAS-15 | 7·39 | 59·76 | 17·67 | 15·18 | |
CMAS-16 | 5·61 | 57·38 | 19·13 | 17·88 | |
CMAS-17 | 15·02 | 49·72 | 29·75 | 5·51 | |
CMAS-18 | 9·99 | 58·51 | 24·75 | 6·75 | |
CMAS-19 | 17·04 | 62·65 | 11·60 | 8·71 | |
CMAS-20 | 17·89 | 48·66 | 27·44 | 6·01 | |
CMAS-21 | 7·00 | 63·39 | 16·60 | 13·01 | |
CMAS-22 | 5·21 | 61·48 | 18·10 | 15·21 |
Abbreviations: Di, CaMgSi2O6; An, CaAl2Si2O8; Fo, Mg2SiO4; En, MgSiO3; Qz, SiO2.
Phases in run products were identified microscopically in reflected light. Characteristic relief, reflectivity, and crystal habit were used for phase identification with verification by back-scattered electron imaging or microprobe analysis when necessary. Compositions of glass, enstatite, diopside, garnet, and sapphirine were determined using the JEOL JXA-733 electron microprobe at Southern Methodist University. Most grains chosen for analysis were larger than 10 µm. Glass regions or pools chosen for analysis have dimensions usually larger than 30 µm. Operating conditions and standards used for analysis are the same as described by Liu & Presnall (1990). We have accepted analyses of phases that have sums between 99 and 101 wt % and have structural formulae with 3·96–4·04 cations per six oxygens (pyroxenes), 7·94–8·06 cations per eight oxygens (garnet), or 13·95–14·05 cations per 20 oxygens (sapphirine).
Several workers have pointed out that glass compositions can be significantly altered by the formation of quench crystals (Cawthorn et al., 1973; Green, 1973; Jaques & Green, 1979, 1980). In our experiments, we have found that this is a problem only when attempting to analyze a glass within a few microns of quench crystals. All of the glass compositions we report here are consistent with results of quenching experiments that bracket the univariant lines. Therefore, we believe these glass compositions are valid in helping to constrain the locations of univariant lines.
Run durations for each primary phase field except corundum were set according to the times established by reversal experiments of Chen & Presnall (1975), Presnall (1976), Presnall et al. (1978),Sen & Presnall (1984), Liu & Presnall (1990), and Milholland & Presnall (1998). Two experiments (Table 2) contain corundum, and as equilibria involving corundum have never been reversed in this laboratory, these runs must be considered as synthesis data.
Run | Mixture* | T (°C) | Time (h) | Phases† |
380-5 | 60An40En | 1460 | 24 | gl+sa+en |
378-7 | 60An40En | 1440 | 24 | gl+sa+en |
374-7 | 60An40En | 1420 | 57·5 | gl+sa+en+gt+di |
380-3 | 80An20En | 1470 | 8 | gl+cor |
380-4 | 80An20En | 1450 | 8 | gl+sa+sp+an |
380-6‡ | AFQ-20 | 1370 | 24 | gl+en+qz+an |
376-8 | AFQ-20 | 1350 | 48 | gl+en+qz+an+di |
380-7 | AFQ-21 | 1490 | 8 | gl+en+sp |
380-10 | AFQ-21 | 1450 | 8 | gl+en+sp+di |
377-18 | AFQ-22 | 1540 | 6 | gl+fo |
381-1 | AFQ-22 | 1520 | 6 | gl+fo |
378-17 | AFQ-22 | 1500 | 8 | gl+fo+en+sp |
378-18 | AFQ-22 | 1480 | 8 | gl+fo+en+sp+di |
379-2‡ | AFQ-23 | 1360 | 24 | gl+qz+an+en |
379-11 | AFQ-25 | 1430 | 10 | gl+sa |
380-12 | AFQ-25 | 1410 | 12 | gl+sa+di+an |
380-15 | AFQ-26 | 1450 | 24 | gl+an |
381-5 | AFQ-26 | 1410 | 24 | gl+an+qz |
380-16 | AFQ-26 | 1390 | 24 | gl+an+qz+en |
381-8 | AFQ-28 | 1420 | 6 | gl+cor+an+sa |
382-1 | AFQ-28 | 1400 | 12 | gl+cor+an+sa |
383-2 | AED-52 | 1490 | 8 | gl |
383-4 | AED-52 | 1470 | 23 | gl+sp |
381-9 | AED-52 | 1450 | 8 | gl+sp |
383-5 | AED-52 | 1430 | 17 | gl+sp+di |
381-10 | AED-54 | 1470 | 8 | gl |
381-12 | AED-54 | 1450 | 8 | gl+di+(px) |
382-4 | AED-54 | 1430 | 24 | gl+sa+di |
372-11 | GS-0 | 1510 | 8 | gl+en+sp+(px) |
373-1 | GS-0 | 1490 | 8 | gl+en+sp+(px) |
378-9 | GS-0 | 1475 | 24 | gl+en+sp+(px) |
375-1 | GS-0 | 1460 | 50 | gl+en+sa+di+(px) |
378-12‡ | GS-6 | 1360 | 24 | gl+qz+an+en |
378-13‡ | GS-8 | 1390 | 24 | gl+sa+en+an |
374-3 | GS-11 | 1430 | 50 | gl+sa |
375-16 | GS-11 | 1410 | 50 | gl+sa+gt+di |
375-17 | GS-11 | 1370 | 51 | gl+di+en+an |
381-14 | CMAS-4 | 1470 | 8 | gl |
381-15 | CMAS-4 | 1450 | 8 | gl+di+en |
379-12 | CMAS-5 | 1500 | 6 | gl |
379-13 | CMAS-5 | 1480 | 8 | gl+en+di |
376-13 | CMAS-5 | 1460 | 48 | gl+en+di |
376-15 | CMAS-5 | 1440 | 48 | gl+en+di+sa |
376-16 | CMAS-5 | 1420 | 48 | gl+en+di+sa |
376-17 | CMAS-5 | 1400 | 48 | en+di+sa |
381-16 | CMAS-7 | 1470 | 22 | gl |
381-17 | CMAS-7 | 1450 | 24 | gl+di |
381-18 | CMAS-7 | 1430 | 24 | gl+di+en |
382-7 | CMAS-9 | 1470 | 24 | gl+qz+di |
382-8 | CMAS-9 | 1430 | 24 | gl+qz+di |
382-10 | CMAS-10 | 1440 | 24 | gl |
382-11 | CMAS-10 | 1420 | 24 | gl+di |
382-12 | CMAS-10 | 1400 | 24 | gl+di+en |
382-14 | CMAS-11 | 1470 | 6 | gl |
382-15 | CMAS-11 | 1450 | 7 | gl+di |
379-15 | CMAS-12 | 1380 | 26 | gl |
379-16 | CMAS-12 | 1360 | 48 | gl+qz+en+di+an |
379-17 | CMAS-12 | 1350 | 48 | gl+qz+en+di+an |
379-18 | CMAS-12 | 1340 | 50 | qz+en+di+an |
383-9 | CMAS-13 | 1500 | 8 | gl |
383-11 | CMAS-13 | 1480 | 21 | gl+di |
383-12 | CMAS-13 | 1460 | 9 | gl+di+sp |
382-16 | CMAS-14 | 1450 | 8 | gl |
383-13 | CMAS-14 | 1430 | 7 | gl+an |
382-17 | CMAS-14 | 1410 | 8 | gl+an+di |
383-14 | CMAS-14 | 1390 | 8 | gl+an+di |
383-15 | CMAS-15 | 1420 | 24 | gl |
383-16 | CMAS-15 | 1400 | 27 | gl+gt+di+en |
383-17 | CMAS-15 | 1380 | 24 | gl+di+en+an |
384-1 | CMAS-16 | 1430 | 7 | gl |
384-2 | CMAS-16 | 1410 | 8 | gl+en |
384-3 | CMAS-16 | 1390 | 23 | gl+en |
384-4 | CMAS-16 | 1370 | 24 | gl+en+di+an |
384-5 | CMAS-17 | 1500 | 8 | gl |
384-6 | CMAS-17 | 1480 | 8 | gl+fo |
384-7 | CMAS-17 | 1460 | 12 | gl+sp+di+en |
388-7 | CMAS-18 | 1500 | 8 | gl |
384-8 | CMAS-18 | 1480 | 17 | gl+sp |
384-9 | CMAS-18 | 1460 | 16 | gl+sp+di |
384-10 | CMAS-18 | 1440 | 8 | gl+sp+di+sa |
384-11 | CMAS-19 | 1460 | 8 | gl |
384-12 | CMAS-19 | 1440 | 19 | gl+di |
384-13 | CMAS-19 | 1400 | 15 | gl+di+an |
Run | Mixture* | T (°C) | Time (h) | Phases† |
380-5 | 60An40En | 1460 | 24 | gl+sa+en |
378-7 | 60An40En | 1440 | 24 | gl+sa+en |
374-7 | 60An40En | 1420 | 57·5 | gl+sa+en+gt+di |
380-3 | 80An20En | 1470 | 8 | gl+cor |
380-4 | 80An20En | 1450 | 8 | gl+sa+sp+an |
380-6‡ | AFQ-20 | 1370 | 24 | gl+en+qz+an |
376-8 | AFQ-20 | 1350 | 48 | gl+en+qz+an+di |
380-7 | AFQ-21 | 1490 | 8 | gl+en+sp |
380-10 | AFQ-21 | 1450 | 8 | gl+en+sp+di |
377-18 | AFQ-22 | 1540 | 6 | gl+fo |
381-1 | AFQ-22 | 1520 | 6 | gl+fo |
378-17 | AFQ-22 | 1500 | 8 | gl+fo+en+sp |
378-18 | AFQ-22 | 1480 | 8 | gl+fo+en+sp+di |
379-2‡ | AFQ-23 | 1360 | 24 | gl+qz+an+en |
379-11 | AFQ-25 | 1430 | 10 | gl+sa |
380-12 | AFQ-25 | 1410 | 12 | gl+sa+di+an |
380-15 | AFQ-26 | 1450 | 24 | gl+an |
381-5 | AFQ-26 | 1410 | 24 | gl+an+qz |
380-16 | AFQ-26 | 1390 | 24 | gl+an+qz+en |
381-8 | AFQ-28 | 1420 | 6 | gl+cor+an+sa |
382-1 | AFQ-28 | 1400 | 12 | gl+cor+an+sa |
383-2 | AED-52 | 1490 | 8 | gl |
383-4 | AED-52 | 1470 | 23 | gl+sp |
381-9 | AED-52 | 1450 | 8 | gl+sp |
383-5 | AED-52 | 1430 | 17 | gl+sp+di |
381-10 | AED-54 | 1470 | 8 | gl |
381-12 | AED-54 | 1450 | 8 | gl+di+(px) |
382-4 | AED-54 | 1430 | 24 | gl+sa+di |
372-11 | GS-0 | 1510 | 8 | gl+en+sp+(px) |
373-1 | GS-0 | 1490 | 8 | gl+en+sp+(px) |
378-9 | GS-0 | 1475 | 24 | gl+en+sp+(px) |
375-1 | GS-0 | 1460 | 50 | gl+en+sa+di+(px) |
378-12‡ | GS-6 | 1360 | 24 | gl+qz+an+en |
378-13‡ | GS-8 | 1390 | 24 | gl+sa+en+an |
374-3 | GS-11 | 1430 | 50 | gl+sa |
375-16 | GS-11 | 1410 | 50 | gl+sa+gt+di |
375-17 | GS-11 | 1370 | 51 | gl+di+en+an |
381-14 | CMAS-4 | 1470 | 8 | gl |
381-15 | CMAS-4 | 1450 | 8 | gl+di+en |
379-12 | CMAS-5 | 1500 | 6 | gl |
379-13 | CMAS-5 | 1480 | 8 | gl+en+di |
376-13 | CMAS-5 | 1460 | 48 | gl+en+di |
376-15 | CMAS-5 | 1440 | 48 | gl+en+di+sa |
376-16 | CMAS-5 | 1420 | 48 | gl+en+di+sa |
376-17 | CMAS-5 | 1400 | 48 | en+di+sa |
381-16 | CMAS-7 | 1470 | 22 | gl |
381-17 | CMAS-7 | 1450 | 24 | gl+di |
381-18 | CMAS-7 | 1430 | 24 | gl+di+en |
382-7 | CMAS-9 | 1470 | 24 | gl+qz+di |
382-8 | CMAS-9 | 1430 | 24 | gl+qz+di |
382-10 | CMAS-10 | 1440 | 24 | gl |
382-11 | CMAS-10 | 1420 | 24 | gl+di |
382-12 | CMAS-10 | 1400 | 24 | gl+di+en |
382-14 | CMAS-11 | 1470 | 6 | gl |
382-15 | CMAS-11 | 1450 | 7 | gl+di |
379-15 | CMAS-12 | 1380 | 26 | gl |
379-16 | CMAS-12 | 1360 | 48 | gl+qz+en+di+an |
379-17 | CMAS-12 | 1350 | 48 | gl+qz+en+di+an |
379-18 | CMAS-12 | 1340 | 50 | qz+en+di+an |
383-9 | CMAS-13 | 1500 | 8 | gl |
383-11 | CMAS-13 | 1480 | 21 | gl+di |
383-12 | CMAS-13 | 1460 | 9 | gl+di+sp |
382-16 | CMAS-14 | 1450 | 8 | gl |
383-13 | CMAS-14 | 1430 | 7 | gl+an |
382-17 | CMAS-14 | 1410 | 8 | gl+an+di |
383-14 | CMAS-14 | 1390 | 8 | gl+an+di |
383-15 | CMAS-15 | 1420 | 24 | gl |
383-16 | CMAS-15 | 1400 | 27 | gl+gt+di+en |
383-17 | CMAS-15 | 1380 | 24 | gl+di+en+an |
384-1 | CMAS-16 | 1430 | 7 | gl |
384-2 | CMAS-16 | 1410 | 8 | gl+en |
384-3 | CMAS-16 | 1390 | 23 | gl+en |
384-4 | CMAS-16 | 1370 | 24 | gl+en+di+an |
384-5 | CMAS-17 | 1500 | 8 | gl |
384-6 | CMAS-17 | 1480 | 8 | gl+fo |
384-7 | CMAS-17 | 1460 | 12 | gl+sp+di+en |
388-7 | CMAS-18 | 1500 | 8 | gl |
384-8 | CMAS-18 | 1480 | 17 | gl+sp |
384-9 | CMAS-18 | 1460 | 16 | gl+sp+di |
384-10 | CMAS-18 | 1440 | 8 | gl+sp+di+sa |
384-11 | CMAS-19 | 1460 | 8 | gl |
384-12 | CMAS-19 | 1440 | 19 | gl+di |
384-13 | CMAS-19 | 1400 | 15 | gl+di+an |
* For example, the designation 60An40En indicates the composition 60% CaAl2Si2O8, 40% MgSiO3, in wt %. (See Table 1 for compositions of mixtures labeled differently.)
† Phase abbreviations: an, anorthite; cor, corundum; di, diopside; en, enstatite; fo, forsterite; gl, glass; gt, garnet; qz, quartz; sa, sapphirine; sp, spinel; (px), pyroxene quench crystals.
‡ Run results from Liu & Presnall (1990).
Run | Mixture* | T (°C) | Time (h) | Phases† |
380-5 | 60An40En | 1460 | 24 | gl+sa+en |
378-7 | 60An40En | 1440 | 24 | gl+sa+en |
374-7 | 60An40En | 1420 | 57·5 | gl+sa+en+gt+di |
380-3 | 80An20En | 1470 | 8 | gl+cor |
380-4 | 80An20En | 1450 | 8 | gl+sa+sp+an |
380-6‡ | AFQ-20 | 1370 | 24 | gl+en+qz+an |
376-8 | AFQ-20 | 1350 | 48 | gl+en+qz+an+di |
380-7 | AFQ-21 | 1490 | 8 | gl+en+sp |
380-10 | AFQ-21 | 1450 | 8 | gl+en+sp+di |
377-18 | AFQ-22 | 1540 | 6 | gl+fo |
381-1 | AFQ-22 | 1520 | 6 | gl+fo |
378-17 | AFQ-22 | 1500 | 8 | gl+fo+en+sp |
378-18 | AFQ-22 | 1480 | 8 | gl+fo+en+sp+di |
379-2‡ | AFQ-23 | 1360 | 24 | gl+qz+an+en |
379-11 | AFQ-25 | 1430 | 10 | gl+sa |
380-12 | AFQ-25 | 1410 | 12 | gl+sa+di+an |
380-15 | AFQ-26 | 1450 | 24 | gl+an |
381-5 | AFQ-26 | 1410 | 24 | gl+an+qz |
380-16 | AFQ-26 | 1390 | 24 | gl+an+qz+en |
381-8 | AFQ-28 | 1420 | 6 | gl+cor+an+sa |
382-1 | AFQ-28 | 1400 | 12 | gl+cor+an+sa |
383-2 | AED-52 | 1490 | 8 | gl |
383-4 | AED-52 | 1470 | 23 | gl+sp |
381-9 | AED-52 | 1450 | 8 | gl+sp |
383-5 | AED-52 | 1430 | 17 | gl+sp+di |
381-10 | AED-54 | 1470 | 8 | gl |
381-12 | AED-54 | 1450 | 8 | gl+di+(px) |
382-4 | AED-54 | 1430 | 24 | gl+sa+di |
372-11 | GS-0 | 1510 | 8 | gl+en+sp+(px) |
373-1 | GS-0 | 1490 | 8 | gl+en+sp+(px) |
378-9 | GS-0 | 1475 | 24 | gl+en+sp+(px) |
375-1 | GS-0 | 1460 | 50 | gl+en+sa+di+(px) |
378-12‡ | GS-6 | 1360 | 24 | gl+qz+an+en |
378-13‡ | GS-8 | 1390 | 24 | gl+sa+en+an |
374-3 | GS-11 | 1430 | 50 | gl+sa |
375-16 | GS-11 | 1410 | 50 | gl+sa+gt+di |
375-17 | GS-11 | 1370 | 51 | gl+di+en+an |
381-14 | CMAS-4 | 1470 | 8 | gl |
381-15 | CMAS-4 | 1450 | 8 | gl+di+en |
379-12 | CMAS-5 | 1500 | 6 | gl |
379-13 | CMAS-5 | 1480 | 8 | gl+en+di |
376-13 | CMAS-5 | 1460 | 48 | gl+en+di |
376-15 | CMAS-5 | 1440 | 48 | gl+en+di+sa |
376-16 | CMAS-5 | 1420 | 48 | gl+en+di+sa |
376-17 | CMAS-5 | 1400 | 48 | en+di+sa |
381-16 | CMAS-7 | 1470 | 22 | gl |
381-17 | CMAS-7 | 1450 | 24 | gl+di |
381-18 | CMAS-7 | 1430 | 24 | gl+di+en |
382-7 | CMAS-9 | 1470 | 24 | gl+qz+di |
382-8 | CMAS-9 | 1430 | 24 | gl+qz+di |
382-10 | CMAS-10 | 1440 | 24 | gl |
382-11 | CMAS-10 | 1420 | 24 | gl+di |
382-12 | CMAS-10 | 1400 | 24 | gl+di+en |
382-14 | CMAS-11 | 1470 | 6 | gl |
382-15 | CMAS-11 | 1450 | 7 | gl+di |
379-15 | CMAS-12 | 1380 | 26 | gl |
379-16 | CMAS-12 | 1360 | 48 | gl+qz+en+di+an |
379-17 | CMAS-12 | 1350 | 48 | gl+qz+en+di+an |
379-18 | CMAS-12 | 1340 | 50 | qz+en+di+an |
383-9 | CMAS-13 | 1500 | 8 | gl |
383-11 | CMAS-13 | 1480 | 21 | gl+di |
383-12 | CMAS-13 | 1460 | 9 | gl+di+sp |
382-16 | CMAS-14 | 1450 | 8 | gl |
383-13 | CMAS-14 | 1430 | 7 | gl+an |
382-17 | CMAS-14 | 1410 | 8 | gl+an+di |
383-14 | CMAS-14 | 1390 | 8 | gl+an+di |
383-15 | CMAS-15 | 1420 | 24 | gl |
383-16 | CMAS-15 | 1400 | 27 | gl+gt+di+en |
383-17 | CMAS-15 | 1380 | 24 | gl+di+en+an |
384-1 | CMAS-16 | 1430 | 7 | gl |
384-2 | CMAS-16 | 1410 | 8 | gl+en |
384-3 | CMAS-16 | 1390 | 23 | gl+en |
384-4 | CMAS-16 | 1370 | 24 | gl+en+di+an |
384-5 | CMAS-17 | 1500 | 8 | gl |
384-6 | CMAS-17 | 1480 | 8 | gl+fo |
384-7 | CMAS-17 | 1460 | 12 | gl+sp+di+en |
388-7 | CMAS-18 | 1500 | 8 | gl |
384-8 | CMAS-18 | 1480 | 17 | gl+sp |
384-9 | CMAS-18 | 1460 | 16 | gl+sp+di |
384-10 | CMAS-18 | 1440 | 8 | gl+sp+di+sa |
384-11 | CMAS-19 | 1460 | 8 | gl |
384-12 | CMAS-19 | 1440 | 19 | gl+di |
384-13 | CMAS-19 | 1400 | 15 | gl+di+an |
Run | Mixture* | T (°C) | Time (h) | Phases† |
380-5 | 60An40En | 1460 | 24 | gl+sa+en |
378-7 | 60An40En | 1440 | 24 | gl+sa+en |
374-7 | 60An40En | 1420 | 57·5 | gl+sa+en+gt+di |
380-3 | 80An20En | 1470 | 8 | gl+cor |
380-4 | 80An20En | 1450 | 8 | gl+sa+sp+an |
380-6‡ | AFQ-20 | 1370 | 24 | gl+en+qz+an |
376-8 | AFQ-20 | 1350 | 48 | gl+en+qz+an+di |
380-7 | AFQ-21 | 1490 | 8 | gl+en+sp |
380-10 | AFQ-21 | 1450 | 8 | gl+en+sp+di |
377-18 | AFQ-22 | 1540 | 6 | gl+fo |
381-1 | AFQ-22 | 1520 | 6 | gl+fo |
378-17 | AFQ-22 | 1500 | 8 | gl+fo+en+sp |
378-18 | AFQ-22 | 1480 | 8 | gl+fo+en+sp+di |
379-2‡ | AFQ-23 | 1360 | 24 | gl+qz+an+en |
379-11 | AFQ-25 | 1430 | 10 | gl+sa |
380-12 | AFQ-25 | 1410 | 12 | gl+sa+di+an |
380-15 | AFQ-26 | 1450 | 24 | gl+an |
381-5 | AFQ-26 | 1410 | 24 | gl+an+qz |
380-16 | AFQ-26 | 1390 | 24 | gl+an+qz+en |
381-8 | AFQ-28 | 1420 | 6 | gl+cor+an+sa |
382-1 | AFQ-28 | 1400 | 12 | gl+cor+an+sa |
383-2 | AED-52 | 1490 | 8 | gl |
383-4 | AED-52 | 1470 | 23 | gl+sp |
381-9 | AED-52 | 1450 | 8 | gl+sp |
383-5 | AED-52 | 1430 | 17 | gl+sp+di |
381-10 | AED-54 | 1470 | 8 | gl |
381-12 | AED-54 | 1450 | 8 | gl+di+(px) |
382-4 | AED-54 | 1430 | 24 | gl+sa+di |
372-11 | GS-0 | 1510 | 8 | gl+en+sp+(px) |
373-1 | GS-0 | 1490 | 8 | gl+en+sp+(px) |
378-9 | GS-0 | 1475 | 24 | gl+en+sp+(px) |
375-1 | GS-0 | 1460 | 50 | gl+en+sa+di+(px) |
378-12‡ | GS-6 | 1360 | 24 | gl+qz+an+en |
378-13‡ | GS-8 | 1390 | 24 | gl+sa+en+an |
374-3 | GS-11 | 1430 | 50 | gl+sa |
375-16 | GS-11 | 1410 | 50 | gl+sa+gt+di |
375-17 | GS-11 | 1370 | 51 | gl+di+en+an |
381-14 | CMAS-4 | 1470 | 8 | gl |
381-15 | CMAS-4 | 1450 | 8 | gl+di+en |
379-12 | CMAS-5 | 1500 | 6 | gl |
379-13 | CMAS-5 | 1480 | 8 | gl+en+di |
376-13 | CMAS-5 | 1460 | 48 | gl+en+di |
376-15 | CMAS-5 | 1440 | 48 | gl+en+di+sa |
376-16 | CMAS-5 | 1420 | 48 | gl+en+di+sa |
376-17 | CMAS-5 | 1400 | 48 | en+di+sa |
381-16 | CMAS-7 | 1470 | 22 | gl |
381-17 | CMAS-7 | 1450 | 24 | gl+di |
381-18 | CMAS-7 | 1430 | 24 | gl+di+en |
382-7 | CMAS-9 | 1470 | 24 | gl+qz+di |
382-8 | CMAS-9 | 1430 | 24 | gl+qz+di |
382-10 | CMAS-10 | 1440 | 24 | gl |
382-11 | CMAS-10 | 1420 | 24 | gl+di |
382-12 | CMAS-10 | 1400 | 24 | gl+di+en |
382-14 | CMAS-11 | 1470 | 6 | gl |
382-15 | CMAS-11 | 1450 | 7 | gl+di |
379-15 | CMAS-12 | 1380 | 26 | gl |
379-16 | CMAS-12 | 1360 | 48 | gl+qz+en+di+an |
379-17 | CMAS-12 | 1350 | 48 | gl+qz+en+di+an |
379-18 | CMAS-12 | 1340 | 50 | qz+en+di+an |
383-9 | CMAS-13 | 1500 | 8 | gl |
383-11 | CMAS-13 | 1480 | 21 | gl+di |
383-12 | CMAS-13 | 1460 | 9 | gl+di+sp |
382-16 | CMAS-14 | 1450 | 8 | gl |
383-13 | CMAS-14 | 1430 | 7 | gl+an |
382-17 | CMAS-14 | 1410 | 8 | gl+an+di |
383-14 | CMAS-14 | 1390 | 8 | gl+an+di |
383-15 | CMAS-15 | 1420 | 24 | gl |
383-16 | CMAS-15 | 1400 | 27 | gl+gt+di+en |
383-17 | CMAS-15 | 1380 | 24 | gl+di+en+an |
384-1 | CMAS-16 | 1430 | 7 | gl |
384-2 | CMAS-16 | 1410 | 8 | gl+en |
384-3 | CMAS-16 | 1390 | 23 | gl+en |
384-4 | CMAS-16 | 1370 | 24 | gl+en+di+an |
384-5 | CMAS-17 | 1500 | 8 | gl |
384-6 | CMAS-17 | 1480 | 8 | gl+fo |
384-7 | CMAS-17 | 1460 | 12 | gl+sp+di+en |
388-7 | CMAS-18 | 1500 | 8 | gl |
384-8 | CMAS-18 | 1480 | 17 | gl+sp |
384-9 | CMAS-18 | 1460 | 16 | gl+sp+di |
384-10 | CMAS-18 | 1440 | 8 | gl+sp+di+sa |
384-11 | CMAS-19 | 1460 | 8 | gl |
384-12 | CMAS-19 | 1440 | 19 | gl+di |
384-13 | CMAS-19 | 1400 | 15 | gl+di+an |
* For example, the designation 60An40En indicates the composition 60% CaAl2Si2O8, 40% MgSiO3, in wt %. (See Table 1 for compositions of mixtures labeled differently.)
† Phase abbreviations: an, anorthite; cor, corundum; di, diopside; en, enstatite; fo, forsterite; gl, glass; gt, garnet; qz, quartz; sa, sapphirine; sp, spinel; (px), pyroxene quench crystals.
‡ Run results from Liu & Presnall (1990).
DATA
Table 2 lists quenching experiments using the starting compositions given in Table 1. Electron microprobe determinations of phase compositions are listed in Tables 3 (glass), 4 (enstatite), 5 (diopside), 6 (garnet), and 7 (sapphirine).
Mixture: | 60An40En | 80An20En | GS-0 | GS-6 | GS-8 | GS-11 | AFQ-20 | AFQ-23 | CMAS-5 | CMAS-12 | CMAS-12 | CMAS-15 |
Run: | 374-7 | 380-4 | 375-1 | 378-12* | 378-13* | 375-17 | 380-6 | 379-2* | 376-15 | 379-16 | 379-17 | 383-17 |
T (°C): | 1420 | 1450 | 1460 | 1360 | 1390 | 1370 | 1370 | 1360 | 1440 | 1360 | 1350 | 1380 |
Phases†: | gl,sa,en,gt,di | gl,sa,sp,an | gl,en,sa,di | gl,qz,an,en | gl,sa,en,an | gl,di,en,an | gl,en,qz,an | gl,qz,an,en | gl,en,sa,di | gl,qz,en,di,an | gl,qz,en,di,an | gl,en,di,an |
Av. of: | 6 | 6 | 6 | 6 | 6 | 3 | 6 | 3 | 7 | 5 | 3 | 6 |
SiO2 | 51·00(0·33)‡ | 48·83(0·62) | 50·52(0·48) | 59·44(0·70) | 53·91(0·37) | 54·07(0·17) | 58·07(0·20) | 57·59(0·44) | 51·11(0·28) | 58·14(0·50) | 57·31(0·07) | 54·06(0·57) |
Al2O3 | 22·00(0·12) | 26·33(0·15) | 21·46(0·24) | 20·84(0·32) | 22·52(0·27) | 21·83(0·42) | 21·36(0·17) | 21·53(0·41) | 21·15(0·20) | 20·87(0·07) | 20·72(0·15) | 22·07(0·11) |
MgO | 12·69(0·25) | 9·03(0·21) | 14·75(0·11) | 8·43(0·56) | 10·48(0·10) | 10·00(0·42) | 8·48(0·10) | 8·65(0·25) | 13·98(0·25) | 8·13(0·03) | 8·48(0·06) | 9·95(0·09) |
CaO | 14·10(0·07) | 15·31(0·89) | 13·83(0·58) | 11·23(0·78) | 12·52(0·50) | 13·87(0·46) | 11·97(0·53) | 12·60(0·20) | 13·68(0·69) | 12·88(0·30) | 12·83(0·27) | 13·33(0·51) |
Sum | 99·79(0·77) | 99·50(1·87) | 100·56(1·41) | 99·94(2·36) | 99·43(1·24) | 99·77(1·47) | 99·88(1·00) | 100·37(1·30) | 99·92(1·42) | 100·02(0·90) | 99·34(0·55) | 99·41(1·28) |
An | 60·15 | 72·20 | 58·23 | 56·89 | 61·80 | 59·71 | 58·35 | 58·54 | 57·75 | 56·94 | 56·91 | 60·58 |
Di | 7·74 | 3·22 | 7·78 | −0·89 | 0·51 | 7·21 | 0·85 | 2·91 | 7·91 | 5·42 | 5·58 | 4·63 |
Fo | 19·68 | 14·80 | 23·07 | 15·02 | 18·23 | 15·15 | 14·54 | 14·09 | 21·85 | 12·42 | 13·09 | 15·97 |
Qz | 12·42 | 9·78 | 10·91 | 28·98 | 19·45 | 17·93 | 26·25 | 24·46 | 12·48 | 25·22 | 24·42 | 18·82 |
Mixture: | 60An40En | 80An20En | GS-0 | GS-6 | GS-8 | GS-11 | AFQ-20 | AFQ-23 | CMAS-5 | CMAS-12 | CMAS-12 | CMAS-15 |
Run: | 374-7 | 380-4 | 375-1 | 378-12* | 378-13* | 375-17 | 380-6 | 379-2* | 376-15 | 379-16 | 379-17 | 383-17 |
T (°C): | 1420 | 1450 | 1460 | 1360 | 1390 | 1370 | 1370 | 1360 | 1440 | 1360 | 1350 | 1380 |
Phases†: | gl,sa,en,gt,di | gl,sa,sp,an | gl,en,sa,di | gl,qz,an,en | gl,sa,en,an | gl,di,en,an | gl,en,qz,an | gl,qz,an,en | gl,en,sa,di | gl,qz,en,di,an | gl,qz,en,di,an | gl,en,di,an |
Av. of: | 6 | 6 | 6 | 6 | 6 | 3 | 6 | 3 | 7 | 5 | 3 | 6 |
SiO2 | 51·00(0·33)‡ | 48·83(0·62) | 50·52(0·48) | 59·44(0·70) | 53·91(0·37) | 54·07(0·17) | 58·07(0·20) | 57·59(0·44) | 51·11(0·28) | 58·14(0·50) | 57·31(0·07) | 54·06(0·57) |
Al2O3 | 22·00(0·12) | 26·33(0·15) | 21·46(0·24) | 20·84(0·32) | 22·52(0·27) | 21·83(0·42) | 21·36(0·17) | 21·53(0·41) | 21·15(0·20) | 20·87(0·07) | 20·72(0·15) | 22·07(0·11) |
MgO | 12·69(0·25) | 9·03(0·21) | 14·75(0·11) | 8·43(0·56) | 10·48(0·10) | 10·00(0·42) | 8·48(0·10) | 8·65(0·25) | 13·98(0·25) | 8·13(0·03) | 8·48(0·06) | 9·95(0·09) |
CaO | 14·10(0·07) | 15·31(0·89) | 13·83(0·58) | 11·23(0·78) | 12·52(0·50) | 13·87(0·46) | 11·97(0·53) | 12·60(0·20) | 13·68(0·69) | 12·88(0·30) | 12·83(0·27) | 13·33(0·51) |
Sum | 99·79(0·77) | 99·50(1·87) | 100·56(1·41) | 99·94(2·36) | 99·43(1·24) | 99·77(1·47) | 99·88(1·00) | 100·37(1·30) | 99·92(1·42) | 100·02(0·90) | 99·34(0·55) | 99·41(1·28) |
An | 60·15 | 72·20 | 58·23 | 56·89 | 61·80 | 59·71 | 58·35 | 58·54 | 57·75 | 56·94 | 56·91 | 60·58 |
Di | 7·74 | 3·22 | 7·78 | −0·89 | 0·51 | 7·21 | 0·85 | 2·91 | 7·91 | 5·42 | 5·58 | 4·63 |
Fo | 19·68 | 14·80 | 23·07 | 15·02 | 18·23 | 15·15 | 14·54 | 14·09 | 21·85 | 12·42 | 13·09 | 15·97 |
Qz | 12·42 | 9·78 | 10·91 | 28·98 | 19·45 | 17·93 | 26·25 | 24·46 | 12·48 | 25·22 | 24·42 | 18·82 |
*Run results from Liu & Presnall (1990).
† Abbreviations as in Table 2.
‡ Numbers in parentheses are one standard deviation.
Mixture: | 60An40En | 80An20En | GS-0 | GS-6 | GS-8 | GS-11 | AFQ-20 | AFQ-23 | CMAS-5 | CMAS-12 | CMAS-12 | CMAS-15 |
Run: | 374-7 | 380-4 | 375-1 | 378-12* | 378-13* | 375-17 | 380-6 | 379-2* | 376-15 | 379-16 | 379-17 | 383-17 |
T (°C): | 1420 | 1450 | 1460 | 1360 | 1390 | 1370 | 1370 | 1360 | 1440 | 1360 | 1350 | 1380 |
Phases†: | gl,sa,en,gt,di | gl,sa,sp,an | gl,en,sa,di | gl,qz,an,en | gl,sa,en,an | gl,di,en,an | gl,en,qz,an | gl,qz,an,en | gl,en,sa,di | gl,qz,en,di,an | gl,qz,en,di,an | gl,en,di,an |
Av. of: | 6 | 6 | 6 | 6 | 6 | 3 | 6 | 3 | 7 | 5 | 3 | 6 |
SiO2 | 51·00(0·33)‡ | 48·83(0·62) | 50·52(0·48) | 59·44(0·70) | 53·91(0·37) | 54·07(0·17) | 58·07(0·20) | 57·59(0·44) | 51·11(0·28) | 58·14(0·50) | 57·31(0·07) | 54·06(0·57) |
Al2O3 | 22·00(0·12) | 26·33(0·15) | 21·46(0·24) | 20·84(0·32) | 22·52(0·27) | 21·83(0·42) | 21·36(0·17) | 21·53(0·41) | 21·15(0·20) | 20·87(0·07) | 20·72(0·15) | 22·07(0·11) |
MgO | 12·69(0·25) | 9·03(0·21) | 14·75(0·11) | 8·43(0·56) | 10·48(0·10) | 10·00(0·42) | 8·48(0·10) | 8·65(0·25) | 13·98(0·25) | 8·13(0·03) | 8·48(0·06) | 9·95(0·09) |
CaO | 14·10(0·07) | 15·31(0·89) | 13·83(0·58) | 11·23(0·78) | 12·52(0·50) | 13·87(0·46) | 11·97(0·53) | 12·60(0·20) | 13·68(0·69) | 12·88(0·30) | 12·83(0·27) | 13·33(0·51) |
Sum | 99·79(0·77) | 99·50(1·87) | 100·56(1·41) | 99·94(2·36) | 99·43(1·24) | 99·77(1·47) | 99·88(1·00) | 100·37(1·30) | 99·92(1·42) | 100·02(0·90) | 99·34(0·55) | 99·41(1·28) |
An | 60·15 | 72·20 | 58·23 | 56·89 | 61·80 | 59·71 | 58·35 | 58·54 | 57·75 | 56·94 | 56·91 | 60·58 |
Di | 7·74 | 3·22 | 7·78 | −0·89 | 0·51 | 7·21 | 0·85 | 2·91 | 7·91 | 5·42 | 5·58 | 4·63 |
Fo | 19·68 | 14·80 | 23·07 | 15·02 | 18·23 | 15·15 | 14·54 | 14·09 | 21·85 | 12·42 | 13·09 | 15·97 |
Qz | 12·42 | 9·78 | 10·91 | 28·98 | 19·45 | 17·93 | 26·25 | 24·46 | 12·48 | 25·22 | 24·42 | 18·82 |
Mixture: | 60An40En | 80An20En | GS-0 | GS-6 | GS-8 | GS-11 | AFQ-20 | AFQ-23 | CMAS-5 | CMAS-12 | CMAS-12 | CMAS-15 |
Run: | 374-7 | 380-4 | 375-1 | 378-12* | 378-13* | 375-17 | 380-6 | 379-2* | 376-15 | 379-16 | 379-17 | 383-17 |
T (°C): | 1420 | 1450 | 1460 | 1360 | 1390 | 1370 | 1370 | 1360 | 1440 | 1360 | 1350 | 1380 |
Phases†: | gl,sa,en,gt,di | gl,sa,sp,an | gl,en,sa,di | gl,qz,an,en | gl,sa,en,an | gl,di,en,an | gl,en,qz,an | gl,qz,an,en | gl,en,sa,di | gl,qz,en,di,an | gl,qz,en,di,an | gl,en,di,an |
Av. of: | 6 | 6 | 6 | 6 | 6 | 3 | 6 | 3 | 7 | 5 | 3 | 6 |
SiO2 | 51·00(0·33)‡ | 48·83(0·62) | 50·52(0·48) | 59·44(0·70) | 53·91(0·37) | 54·07(0·17) | 58·07(0·20) | 57·59(0·44) | 51·11(0·28) | 58·14(0·50) | 57·31(0·07) | 54·06(0·57) |
Al2O3 | 22·00(0·12) | 26·33(0·15) | 21·46(0·24) | 20·84(0·32) | 22·52(0·27) | 21·83(0·42) | 21·36(0·17) | 21·53(0·41) | 21·15(0·20) | 20·87(0·07) | 20·72(0·15) | 22·07(0·11) |
MgO | 12·69(0·25) | 9·03(0·21) | 14·75(0·11) | 8·43(0·56) | 10·48(0·10) | 10·00(0·42) | 8·48(0·10) | 8·65(0·25) | 13·98(0·25) | 8·13(0·03) | 8·48(0·06) | 9·95(0·09) |
CaO | 14·10(0·07) | 15·31(0·89) | 13·83(0·58) | 11·23(0·78) | 12·52(0·50) | 13·87(0·46) | 11·97(0·53) | 12·60(0·20) | 13·68(0·69) | 12·88(0·30) | 12·83(0·27) | 13·33(0·51) |
Sum | 99·79(0·77) | 99·50(1·87) | 100·56(1·41) | 99·94(2·36) | 99·43(1·24) | 99·77(1·47) | 99·88(1·00) | 100·37(1·30) | 99·92(1·42) | 100·02(0·90) | 99·34(0·55) | 99·41(1·28) |
An | 60·15 | 72·20 | 58·23 | 56·89 | 61·80 | 59·71 | 58·35 | 58·54 | 57·75 | 56·94 | 56·91 | 60·58 |
Di | 7·74 | 3·22 | 7·78 | −0·89 | 0·51 | 7·21 | 0·85 | 2·91 | 7·91 | 5·42 | 5·58 | 4·63 |
Fo | 19·68 | 14·80 | 23·07 | 15·02 | 18·23 | 15·15 | 14·54 | 14·09 | 21·85 | 12·42 | 13·09 | 15·97 |
Qz | 12·42 | 9·78 | 10·91 | 28·98 | 19·45 | 17·93 | 26·25 | 24·46 | 12·48 | 25·22 | 24·42 | 18·82 |
*Run results from Liu & Presnall (1990).
† Abbreviations as in Table 2.
‡ Numbers in parentheses are one standard deviation.
Mixture: | 60An40En | GS-0 | GS-6 | GS-11 | AFQ-20 | AFQ-20 | AFQ-22 | CMAS-5 | CMAS-12 | CMAS-15 | CMAS-15 | CMAS-16 | CMAS-17 |
Run: | 374-7 | 375-1 | 378-12* | 375-17 | 380-6* | 376-8 | 378-17 | 376-15 | 379-16 | 383-16 | 383-17 | 384-4 | 384-7 |
T (°C): | 1420 | 1460 | 1360 | 1370 | 1370 | 1350 | 1500 | 1440 | 1360 | 1400 | 1380 | 1370 | 1460 |
Phases†: | gl,sa,en,gt,di | gl,en,sa,di, | gl,qz,an,en | gl,di,en,an | gl,en,qz,an | gl,en,qz,an,di | gl,fo,en,sp | gl,en,di,sa | gl,qz,en,di,an | gl,gt,di,en | gl,di,en,an | gl,en,di,an | gl,sp,en,di |
(px) | |||||||||||||
Av. of: | 6 | 3 | 2 | 2 | 4 | 8 | 4 | 3 | 8 | 4 | 4 | 3 | 4 |
SiO2 | 51·87(0·45)‡ | 52·29(0·23) | 54·56 | 52·26 | 53·09(0·38) | 53·68(0·34) | 54·42(0·28) | 51·96(1·11) | 53·04(0·30) | 51·24(0·22) | 51·50(0·27) | 52·35(0·69) | 53·08(0·63) |
Al2O3 | 13·72(0·42) | 12·99(0·33) | 9·86 | 12·85 | 11·77(0·43) | 11·07(0·20) | 9·65(0·45) | 12·66(1·30) | 11·66(0·57) | 14·53(0·28) | 14·00(0·36) | 13·32(0·69) | 11·02(1·00) |
MgO | 32·76(0·54) | 33·48(0·50) | 34·58 | 33·33 | 33·49(0·43) | 33·88(0·60) | 34·62(0·54) | 33·36(0·75) | 33·44(0·79) | 32·42(0·34) | 32·89(0·35) | 32·32(0·94) | 33·72(0·86) |
CaO | 2·03(0·32) | 1·91(0·07) | 1·51 | 1·78 | 1·91(0·19) | 1·79(0·10) | 1·64(0·24) | 1·97(0·18) | 1·86(0·24) | 1·72(0·09) | 1·88(0·20) | 2·55(0·66) | 2·34(0·09) |
Sum | 100·38(1·73) | 100·67(1·13) | 100·51 | 100·22 | 100·26(1·43) | 100·42(1·24) | 100·33(1·51) | 99·95(3·34) | 100·00(1·90) | 99·91(0·93) | 100·27(1·18) | 100·54(2·98) | 100·16(2·58) |
Number of cations for 6 oxygens | |||||||||||||
Si | 1·738 | 1·748 | 1·822 | 1·754 | 1·780 | 1·797 | 1·821 | 1·750 | 1·782 | 1·724 | 1·728 | 1·752 | 1·784 |
Al(IV) | 0·262 | 0·252 | 0·178 | 0·246 | 0·220 | 0·206 | 0·179 | 0·250 | 0·218 | 0·276 | 0·272 | 0·248 | 0·216 |
Al(VI) | 0·279 | 0·259 | 0·210 | 0·262 | 0·244 | 0·230 | 0·201 | 0·253 | 0·243 | 0·300 | 0·281 | 0·277 | 0·220 |
Mg | 1·636 | 1·668 | 1·720 | 1·666 | 1·673 | 1·684 | 1·726 | 1·674 | 1·674 | 1·625 | 1·644 | 1·613 | 1·689 |
Ca | 0·073 | 0·068 | 0·054 | 0·064 | 0·068 | 0·064 | 0·056 | 0·071 | 0·066 | 0·061 | 0·067 | 0·090 | 0·084 |
Sum | 3·988 | 3·995 | 3·984 | 3·992 | 3·985 | 3·981 | 3·983 | 3·998 | 3·983 | 3·986 | 3·992 | 3·980 | 3·993 |
Mixture: | 60An40En | GS-0 | GS-6 | GS-11 | AFQ-20 | AFQ-20 | AFQ-22 | CMAS-5 | CMAS-12 | CMAS-15 | CMAS-15 | CMAS-16 | CMAS-17 |
Run: | 374-7 | 375-1 | 378-12* | 375-17 | 380-6* | 376-8 | 378-17 | 376-15 | 379-16 | 383-16 | 383-17 | 384-4 | 384-7 |
T (°C): | 1420 | 1460 | 1360 | 1370 | 1370 | 1350 | 1500 | 1440 | 1360 | 1400 | 1380 | 1370 | 1460 |
Phases†: | gl,sa,en,gt,di | gl,en,sa,di, | gl,qz,an,en | gl,di,en,an | gl,en,qz,an | gl,en,qz,an,di | gl,fo,en,sp | gl,en,di,sa | gl,qz,en,di,an | gl,gt,di,en | gl,di,en,an | gl,en,di,an | gl,sp,en,di |
(px) | |||||||||||||
Av. of: | 6 | 3 | 2 | 2 | 4 | 8 | 4 | 3 | 8 | 4 | 4 | 3 | 4 |
SiO2 | 51·87(0·45)‡ | 52·29(0·23) | 54·56 | 52·26 | 53·09(0·38) | 53·68(0·34) | 54·42(0·28) | 51·96(1·11) | 53·04(0·30) | 51·24(0·22) | 51·50(0·27) | 52·35(0·69) | 53·08(0·63) |
Al2O3 | 13·72(0·42) | 12·99(0·33) | 9·86 | 12·85 | 11·77(0·43) | 11·07(0·20) | 9·65(0·45) | 12·66(1·30) | 11·66(0·57) | 14·53(0·28) | 14·00(0·36) | 13·32(0·69) | 11·02(1·00) |
MgO | 32·76(0·54) | 33·48(0·50) | 34·58 | 33·33 | 33·49(0·43) | 33·88(0·60) | 34·62(0·54) | 33·36(0·75) | 33·44(0·79) | 32·42(0·34) | 32·89(0·35) | 32·32(0·94) | 33·72(0·86) |
CaO | 2·03(0·32) | 1·91(0·07) | 1·51 | 1·78 | 1·91(0·19) | 1·79(0·10) | 1·64(0·24) | 1·97(0·18) | 1·86(0·24) | 1·72(0·09) | 1·88(0·20) | 2·55(0·66) | 2·34(0·09) |
Sum | 100·38(1·73) | 100·67(1·13) | 100·51 | 100·22 | 100·26(1·43) | 100·42(1·24) | 100·33(1·51) | 99·95(3·34) | 100·00(1·90) | 99·91(0·93) | 100·27(1·18) | 100·54(2·98) | 100·16(2·58) |
Number of cations for 6 oxygens | |||||||||||||
Si | 1·738 | 1·748 | 1·822 | 1·754 | 1·780 | 1·797 | 1·821 | 1·750 | 1·782 | 1·724 | 1·728 | 1·752 | 1·784 |
Al(IV) | 0·262 | 0·252 | 0·178 | 0·246 | 0·220 | 0·206 | 0·179 | 0·250 | 0·218 | 0·276 | 0·272 | 0·248 | 0·216 |
Al(VI) | 0·279 | 0·259 | 0·210 | 0·262 | 0·244 | 0·230 | 0·201 | 0·253 | 0·243 | 0·300 | 0·281 | 0·277 | 0·220 |
Mg | 1·636 | 1·668 | 1·720 | 1·666 | 1·673 | 1·684 | 1·726 | 1·674 | 1·674 | 1·625 | 1·644 | 1·613 | 1·689 |
Ca | 0·073 | 0·068 | 0·054 | 0·064 | 0·068 | 0·064 | 0·056 | 0·071 | 0·066 | 0·061 | 0·067 | 0·090 | 0·084 |
Sum | 3·988 | 3·995 | 3·984 | 3·992 | 3·985 | 3·981 | 3·983 | 3·998 | 3·983 | 3·986 | 3·992 | 3·980 | 3·993 |
*Run results from Liu & Presnall (1990).
† Abbreviations same as in Table 2.
‡ Numbers in parentheses are one standard deviation.
Mixture: | 60An40En | GS-0 | GS-6 | GS-11 | AFQ-20 | AFQ-20 | AFQ-22 | CMAS-5 | CMAS-12 | CMAS-15 | CMAS-15 | CMAS-16 | CMAS-17 |
Run: | 374-7 | 375-1 | 378-12* | 375-17 | 380-6* | 376-8 | 378-17 | 376-15 | 379-16 | 383-16 | 383-17 | 384-4 | 384-7 |
T (°C): | 1420 | 1460 | 1360 | 1370 | 1370 | 1350 | 1500 | 1440 | 1360 | 1400 | 1380 | 1370 | 1460 |
Phases†: | gl,sa,en,gt,di | gl,en,sa,di, | gl,qz,an,en | gl,di,en,an | gl,en,qz,an | gl,en,qz,an,di | gl,fo,en,sp | gl,en,di,sa | gl,qz,en,di,an | gl,gt,di,en | gl,di,en,an | gl,en,di,an | gl,sp,en,di |
(px) | |||||||||||||
Av. of: | 6 | 3 | 2 | 2 | 4 | 8 | 4 | 3 | 8 | 4 | 4 | 3 | 4 |
SiO2 | 51·87(0·45)‡ | 52·29(0·23) | 54·56 | 52·26 | 53·09(0·38) | 53·68(0·34) | 54·42(0·28) | 51·96(1·11) | 53·04(0·30) | 51·24(0·22) | 51·50(0·27) | 52·35(0·69) | 53·08(0·63) |
Al2O3 | 13·72(0·42) | 12·99(0·33) | 9·86 | 12·85 | 11·77(0·43) | 11·07(0·20) | 9·65(0·45) | 12·66(1·30) | 11·66(0·57) | 14·53(0·28) | 14·00(0·36) | 13·32(0·69) | 11·02(1·00) |
MgO | 32·76(0·54) | 33·48(0·50) | 34·58 | 33·33 | 33·49(0·43) | 33·88(0·60) | 34·62(0·54) | 33·36(0·75) | 33·44(0·79) | 32·42(0·34) | 32·89(0·35) | 32·32(0·94) | 33·72(0·86) |
CaO | 2·03(0·32) | 1·91(0·07) | 1·51 | 1·78 | 1·91(0·19) | 1·79(0·10) | 1·64(0·24) | 1·97(0·18) | 1·86(0·24) | 1·72(0·09) | 1·88(0·20) | 2·55(0·66) | 2·34(0·09) |
Sum | 100·38(1·73) | 100·67(1·13) | 100·51 | 100·22 | 100·26(1·43) | 100·42(1·24) | 100·33(1·51) | 99·95(3·34) | 100·00(1·90) | 99·91(0·93) | 100·27(1·18) | 100·54(2·98) | 100·16(2·58) |
Number of cations for 6 oxygens | |||||||||||||
Si | 1·738 | 1·748 | 1·822 | 1·754 | 1·780 | 1·797 | 1·821 | 1·750 | 1·782 | 1·724 | 1·728 | 1·752 | 1·784 |
Al(IV) | 0·262 | 0·252 | 0·178 | 0·246 | 0·220 | 0·206 | 0·179 | 0·250 | 0·218 | 0·276 | 0·272 | 0·248 | 0·216 |
Al(VI) | 0·279 | 0·259 | 0·210 | 0·262 | 0·244 | 0·230 | 0·201 | 0·253 | 0·243 | 0·300 | 0·281 | 0·277 | 0·220 |
Mg | 1·636 | 1·668 | 1·720 | 1·666 | 1·673 | 1·684 | 1·726 | 1·674 | 1·674 | 1·625 | 1·644 | 1·613 | 1·689 |
Ca | 0·073 | 0·068 | 0·054 | 0·064 | 0·068 | 0·064 | 0·056 | 0·071 | 0·066 | 0·061 | 0·067 | 0·090 | 0·084 |
Sum | 3·988 | 3·995 | 3·984 | 3·992 | 3·985 | 3·981 | 3·983 | 3·998 | 3·983 | 3·986 | 3·992 | 3·980 | 3·993 |
Mixture: | 60An40En | GS-0 | GS-6 | GS-11 | AFQ-20 | AFQ-20 | AFQ-22 | CMAS-5 | CMAS-12 | CMAS-15 | CMAS-15 | CMAS-16 | CMAS-17 |
Run: | 374-7 | 375-1 | 378-12* | 375-17 | 380-6* | 376-8 | 378-17 | 376-15 | 379-16 | 383-16 | 383-17 | 384-4 | 384-7 |
T (°C): | 1420 | 1460 | 1360 | 1370 | 1370 | 1350 | 1500 | 1440 | 1360 | 1400 | 1380 | 1370 | 1460 |
Phases†: | gl,sa,en,gt,di | gl,en,sa,di, | gl,qz,an,en | gl,di,en,an | gl,en,qz,an | gl,en,qz,an,di | gl,fo,en,sp | gl,en,di,sa | gl,qz,en,di,an | gl,gt,di,en | gl,di,en,an | gl,en,di,an | gl,sp,en,di |
(px) | |||||||||||||
Av. of: | 6 | 3 | 2 | 2 | 4 | 8 | 4 | 3 | 8 | 4 | 4 | 3 | 4 |
SiO2 | 51·87(0·45)‡ | 52·29(0·23) | 54·56 | 52·26 | 53·09(0·38) | 53·68(0·34) | 54·42(0·28) | 51·96(1·11) | 53·04(0·30) | 51·24(0·22) | 51·50(0·27) | 52·35(0·69) | 53·08(0·63) |
Al2O3 | 13·72(0·42) | 12·99(0·33) | 9·86 | 12·85 | 11·77(0·43) | 11·07(0·20) | 9·65(0·45) | 12·66(1·30) | 11·66(0·57) | 14·53(0·28) | 14·00(0·36) | 13·32(0·69) | 11·02(1·00) |
MgO | 32·76(0·54) | 33·48(0·50) | 34·58 | 33·33 | 33·49(0·43) | 33·88(0·60) | 34·62(0·54) | 33·36(0·75) | 33·44(0·79) | 32·42(0·34) | 32·89(0·35) | 32·32(0·94) | 33·72(0·86) |
CaO | 2·03(0·32) | 1·91(0·07) | 1·51 | 1·78 | 1·91(0·19) | 1·79(0·10) | 1·64(0·24) | 1·97(0·18) | 1·86(0·24) | 1·72(0·09) | 1·88(0·20) | 2·55(0·66) | 2·34(0·09) |
Sum | 100·38(1·73) | 100·67(1·13) | 100·51 | 100·22 | 100·26(1·43) | 100·42(1·24) | 100·33(1·51) | 99·95(3·34) | 100·00(1·90) | 99·91(0·93) | 100·27(1·18) | 100·54(2·98) | 100·16(2·58) |
Number of cations for 6 oxygens | |||||||||||||
Si | 1·738 | 1·748 | 1·822 | 1·754 | 1·780 | 1·797 | 1·821 | 1·750 | 1·782 | 1·724 | 1·728 | 1·752 | 1·784 |
Al(IV) | 0·262 | 0·252 | 0·178 | 0·246 | 0·220 | 0·206 | 0·179 | 0·250 | 0·218 | 0·276 | 0·272 | 0·248 | 0·216 |
Al(VI) | 0·279 | 0·259 | 0·210 | 0·262 | 0·244 | 0·230 | 0·201 | 0·253 | 0·243 | 0·300 | 0·281 | 0·277 | 0·220 |
Mg | 1·636 | 1·668 | 1·720 | 1·666 | 1·673 | 1·684 | 1·726 | 1·674 | 1·674 | 1·625 | 1·644 | 1·613 | 1·689 |
Ca | 0·073 | 0·068 | 0·054 | 0·064 | 0·068 | 0·064 | 0·056 | 0·071 | 0·066 | 0·061 | 0·067 | 0·090 | 0·084 |
Sum | 3·988 | 3·995 | 3·984 | 3·992 | 3·985 | 3·981 | 3·983 | 3·998 | 3·983 | 3·986 | 3·992 | 3·980 | 3·993 |
*Run results from Liu & Presnall (1990).
† Abbreviations same as in Table 2.
‡ Numbers in parentheses are one standard deviation.
Mixture: | 60An40En | GS-0 | GS-11 | GS-11 | AFQ-21 | AFQ-25 | CMAS-5 | CMAS-12 | CMAS-15 | CMAS-15 | CMAS-16 | CMAS-17 | CMAS-18 |
Run: | 374-7 | 375-1 | 375-16 | 375-17 | 380-10 | 380-12 | 376-15 | 379-16 | 383-16 | 383-17 | 384-4 | 384-7 | 384-10 |
T (°C): | 1420 | 1460 | 1410 | 1370 | 1450 | 1410 | 1440 | 1360 | 1400 | 1380 | 1370 | 1460 | 1440 |
Phases*: | gl,sa,en,gt,di, | gl,en,sa,di, | gl,sa,gt,di | gl,di,en,an | gl,en,sp,di | gl,sa,di,an | gl,en,di,sa | gl,qz,en,di,an | gl,gt,di,en | gl,di,en,an | gl,en,di,an | gl,sp,di,en | gl,sp,di,sa |
(px) | |||||||||||||
Av. of: | 7 | 3 | 4 | 1 | 1 | 3 | 3 | 10 | 2 | 3 | 1 | 2 | 2 |
SiO2 | 49·08(0·29)† | 49·66(0·36) | 48·02(0·34) | 49·12 | 50·28 | 47·41(0·50) | 49·07(0·22) | 50·64(0·30) | 48·46 | 49·31(0·35) | 50·44 | 50·70 | 49·20 |
Al2O3 | 13·94(0·30) | 12·86(0·03) | 15·47(0·31) | 13·91 | 12·80 | 16·08(0·31) | 13·21(0·09) | 12·06(0·21) | 15·36 | 14·59(0·58) | 13·23 | 10·90 | 13·68 |
MgO | 19·20(0·25) | 20·16(0·30) | 17·80(0·46) | 19·61 | 22·68 | 15·76(0·20) | 19·76(0·39) | 19·08(0·21) | 18·34 | 19·12(0·54) | 19·35 | 22·50 | 20·40 |
CaO | 17·72(0·59) | 17·16(0·38) | 18·95(0·38) | 16·70 | 14·83 | 20·42(0·56) | 17·43(0·54) | 18·19(0·27) | 17·16 | 17·33(0·64) | 17·47 | 15·22 | 16·40 |
Sum | 99·94(1·43) | 99·84(1·07) | 100·24(1·49) | 99·34 | 100·59 | 99·67(1·57) | 99·47(1·24) | 99·97(0·99) | 99·32 | 100·35(2·11) | 100·49 | 99·32 | 99·68 |
Number of cations for 6 oxygens | |||||||||||||
Si | 1·727 | 1·747 | 1·692 | 1·734 | 1·744 | 1·686 | 1·736 | 1·781 | 1·712 | 1·725 | 1·760 | 1·784 | 1·730 |
Al(IV) | 0·273 | 0·253 | 0·308 | 0·266 | 0·256 | 0·314 | 0·264 | 0·219 | 0·288 | 0·275 | 0·240 | 0·216 | 0·270 |
AI(VI) | 0·305 | 0·280 | 0·334 | 0·312 | 0·267 | 0·360 | 0·287 | 0·280 | 0·351 | 0·326 | 0·304 | 0·235 | 0·296 |
Mg | 1·007 | 1·057 | 0·934 | 1·032 | 1·173 | 0·835 | 1·042 | 1·000 | 0·966 | 0·997 | 1·006 | 1·179 | 1·069 |
Ca | 0·670 | 0·646 | 0·715 | 0·631 | 0·551 | 0·778 | 0·661 | 0·685 | 0·649 | 0·649 | 0·652 | 0·573 | 0·618 |
Sum | 3·982 | 3·983 | 3·983 | 3·975 | 3·990 | 3·973 | 3·990 | 3·965 | 3·966 | 3·972 | 3·962 | 3·987 | 3·983 |
Mixture: | 60An40En | GS-0 | GS-11 | GS-11 | AFQ-21 | AFQ-25 | CMAS-5 | CMAS-12 | CMAS-15 | CMAS-15 | CMAS-16 | CMAS-17 | CMAS-18 |
Run: | 374-7 | 375-1 | 375-16 | 375-17 | 380-10 | 380-12 | 376-15 | 379-16 | 383-16 | 383-17 | 384-4 | 384-7 | 384-10 |
T (°C): | 1420 | 1460 | 1410 | 1370 | 1450 | 1410 | 1440 | 1360 | 1400 | 1380 | 1370 | 1460 | 1440 |
Phases*: | gl,sa,en,gt,di, | gl,en,sa,di, | gl,sa,gt,di | gl,di,en,an | gl,en,sp,di | gl,sa,di,an | gl,en,di,sa | gl,qz,en,di,an | gl,gt,di,en | gl,di,en,an | gl,en,di,an | gl,sp,di,en | gl,sp,di,sa |
(px) | |||||||||||||
Av. of: | 7 | 3 | 4 | 1 | 1 | 3 | 3 | 10 | 2 | 3 | 1 | 2 | 2 |
SiO2 | 49·08(0·29)† | 49·66(0·36) | 48·02(0·34) | 49·12 | 50·28 | 47·41(0·50) | 49·07(0·22) | 50·64(0·30) | 48·46 | 49·31(0·35) | 50·44 | 50·70 | 49·20 |
Al2O3 | 13·94(0·30) | 12·86(0·03) | 15·47(0·31) | 13·91 | 12·80 | 16·08(0·31) | 13·21(0·09) | 12·06(0·21) | 15·36 | 14·59(0·58) | 13·23 | 10·90 | 13·68 |
MgO | 19·20(0·25) | 20·16(0·30) | 17·80(0·46) | 19·61 | 22·68 | 15·76(0·20) | 19·76(0·39) | 19·08(0·21) | 18·34 | 19·12(0·54) | 19·35 | 22·50 | 20·40 |
CaO | 17·72(0·59) | 17·16(0·38) | 18·95(0·38) | 16·70 | 14·83 | 20·42(0·56) | 17·43(0·54) | 18·19(0·27) | 17·16 | 17·33(0·64) | 17·47 | 15·22 | 16·40 |
Sum | 99·94(1·43) | 99·84(1·07) | 100·24(1·49) | 99·34 | 100·59 | 99·67(1·57) | 99·47(1·24) | 99·97(0·99) | 99·32 | 100·35(2·11) | 100·49 | 99·32 | 99·68 |
Number of cations for 6 oxygens | |||||||||||||
Si | 1·727 | 1·747 | 1·692 | 1·734 | 1·744 | 1·686 | 1·736 | 1·781 | 1·712 | 1·725 | 1·760 | 1·784 | 1·730 |
Al(IV) | 0·273 | 0·253 | 0·308 | 0·266 | 0·256 | 0·314 | 0·264 | 0·219 | 0·288 | 0·275 | 0·240 | 0·216 | 0·270 |
AI(VI) | 0·305 | 0·280 | 0·334 | 0·312 | 0·267 | 0·360 | 0·287 | 0·280 | 0·351 | 0·326 | 0·304 | 0·235 | 0·296 |
Mg | 1·007 | 1·057 | 0·934 | 1·032 | 1·173 | 0·835 | 1·042 | 1·000 | 0·966 | 0·997 | 1·006 | 1·179 | 1·069 |
Ca | 0·670 | 0·646 | 0·715 | 0·631 | 0·551 | 0·778 | 0·661 | 0·685 | 0·649 | 0·649 | 0·652 | 0·573 | 0·618 |
Sum | 3·982 | 3·983 | 3·983 | 3·975 | 3·990 | 3·973 | 3·990 | 3·965 | 3·966 | 3·972 | 3·962 | 3·987 | 3·983 |
*Abbreviations same as in Table 2.
† Numbers in parentheses are one standard deviation.
Mixture: | 60An40En | GS-0 | GS-11 | GS-11 | AFQ-21 | AFQ-25 | CMAS-5 | CMAS-12 | CMAS-15 | CMAS-15 | CMAS-16 | CMAS-17 | CMAS-18 |
Run: | 374-7 | 375-1 | 375-16 | 375-17 | 380-10 | 380-12 | 376-15 | 379-16 | 383-16 | 383-17 | 384-4 | 384-7 | 384-10 |
T (°C): | 1420 | 1460 | 1410 | 1370 | 1450 | 1410 | 1440 | 1360 | 1400 | 1380 | 1370 | 1460 | 1440 |
Phases*: | gl,sa,en,gt,di, | gl,en,sa,di, | gl,sa,gt,di | gl,di,en,an | gl,en,sp,di | gl,sa,di,an | gl,en,di,sa | gl,qz,en,di,an | gl,gt,di,en | gl,di,en,an | gl,en,di,an | gl,sp,di,en | gl,sp,di,sa |
(px) | |||||||||||||
Av. of: | 7 | 3 | 4 | 1 | 1 | 3 | 3 | 10 | 2 | 3 | 1 | 2 | 2 |
SiO2 | 49·08(0·29)† | 49·66(0·36) | 48·02(0·34) | 49·12 | 50·28 | 47·41(0·50) | 49·07(0·22) | 50·64(0·30) | 48·46 | 49·31(0·35) | 50·44 | 50·70 | 49·20 |
Al2O3 | 13·94(0·30) | 12·86(0·03) | 15·47(0·31) | 13·91 | 12·80 | 16·08(0·31) | 13·21(0·09) | 12·06(0·21) | 15·36 | 14·59(0·58) | 13·23 | 10·90 | 13·68 |
MgO | 19·20(0·25) | 20·16(0·30) | 17·80(0·46) | 19·61 | 22·68 | 15·76(0·20) | 19·76(0·39) | 19·08(0·21) | 18·34 | 19·12(0·54) | 19·35 | 22·50 | 20·40 |
CaO | 17·72(0·59) | 17·16(0·38) | 18·95(0·38) | 16·70 | 14·83 | 20·42(0·56) | 17·43(0·54) | 18·19(0·27) | 17·16 | 17·33(0·64) | 17·47 | 15·22 | 16·40 |
Sum | 99·94(1·43) | 99·84(1·07) | 100·24(1·49) | 99·34 | 100·59 | 99·67(1·57) | 99·47(1·24) | 99·97(0·99) | 99·32 | 100·35(2·11) | 100·49 | 99·32 | 99·68 |
Number of cations for 6 oxygens | |||||||||||||
Si | 1·727 | 1·747 | 1·692 | 1·734 | 1·744 | 1·686 | 1·736 | 1·781 | 1·712 | 1·725 | 1·760 | 1·784 | 1·730 |
Al(IV) | 0·273 | 0·253 | 0·308 | 0·266 | 0·256 | 0·314 | 0·264 | 0·219 | 0·288 | 0·275 | 0·240 | 0·216 | 0·270 |
AI(VI) | 0·305 | 0·280 | 0·334 | 0·312 | 0·267 | 0·360 | 0·287 | 0·280 | 0·351 | 0·326 | 0·304 | 0·235 | 0·296 |
Mg | 1·007 | 1·057 | 0·934 | 1·032 | 1·173 | 0·835 | 1·042 | 1·000 | 0·966 | 0·997 | 1·006 | 1·179 | 1·069 |
Ca | 0·670 | 0·646 | 0·715 | 0·631 | 0·551 | 0·778 | 0·661 | 0·685 | 0·649 | 0·649 | 0·652 | 0·573 | 0·618 |
Sum | 3·982 | 3·983 | 3·983 | 3·975 | 3·990 | 3·973 | 3·990 | 3·965 | 3·966 | 3·972 | 3·962 | 3·987 | 3·983 |
Mixture: | 60An40En | GS-0 | GS-11 | GS-11 | AFQ-21 | AFQ-25 | CMAS-5 | CMAS-12 | CMAS-15 | CMAS-15 | CMAS-16 | CMAS-17 | CMAS-18 |
Run: | 374-7 | 375-1 | 375-16 | 375-17 | 380-10 | 380-12 | 376-15 | 379-16 | 383-16 | 383-17 | 384-4 | 384-7 | 384-10 |
T (°C): | 1420 | 1460 | 1410 | 1370 | 1450 | 1410 | 1440 | 1360 | 1400 | 1380 | 1370 | 1460 | 1440 |
Phases*: | gl,sa,en,gt,di, | gl,en,sa,di, | gl,sa,gt,di | gl,di,en,an | gl,en,sp,di | gl,sa,di,an | gl,en,di,sa | gl,qz,en,di,an | gl,gt,di,en | gl,di,en,an | gl,en,di,an | gl,sp,di,en | gl,sp,di,sa |
(px) | |||||||||||||
Av. of: | 7 | 3 | 4 | 1 | 1 | 3 | 3 | 10 | 2 | 3 | 1 | 2 | 2 |
SiO2 | 49·08(0·29)† | 49·66(0·36) | 48·02(0·34) | 49·12 | 50·28 | 47·41(0·50) | 49·07(0·22) | 50·64(0·30) | 48·46 | 49·31(0·35) | 50·44 | 50·70 | 49·20 |
Al2O3 | 13·94(0·30) | 12·86(0·03) | 15·47(0·31) | 13·91 | 12·80 | 16·08(0·31) | 13·21(0·09) | 12·06(0·21) | 15·36 | 14·59(0·58) | 13·23 | 10·90 | 13·68 |
MgO | 19·20(0·25) | 20·16(0·30) | 17·80(0·46) | 19·61 | 22·68 | 15·76(0·20) | 19·76(0·39) | 19·08(0·21) | 18·34 | 19·12(0·54) | 19·35 | 22·50 | 20·40 |
CaO | 17·72(0·59) | 17·16(0·38) | 18·95(0·38) | 16·70 | 14·83 | 20·42(0·56) | 17·43(0·54) | 18·19(0·27) | 17·16 | 17·33(0·64) | 17·47 | 15·22 | 16·40 |
Sum | 99·94(1·43) | 99·84(1·07) | 100·24(1·49) | 99·34 | 100·59 | 99·67(1·57) | 99·47(1·24) | 99·97(0·99) | 99·32 | 100·35(2·11) | 100·49 | 99·32 | 99·68 |
Number of cations for 6 oxygens | |||||||||||||
Si | 1·727 | 1·747 | 1·692 | 1·734 | 1·744 | 1·686 | 1·736 | 1·781 | 1·712 | 1·725 | 1·760 | 1·784 | 1·730 |
Al(IV) | 0·273 | 0·253 | 0·308 | 0·266 | 0·256 | 0·314 | 0·264 | 0·219 | 0·288 | 0·275 | 0·240 | 0·216 | 0·270 |
AI(VI) | 0·305 | 0·280 | 0·334 | 0·312 | 0·267 | 0·360 | 0·287 | 0·280 | 0·351 | 0·326 | 0·304 | 0·235 | 0·296 |
Mg | 1·007 | 1·057 | 0·934 | 1·032 | 1·173 | 0·835 | 1·042 | 1·000 | 0·966 | 0·997 | 1·006 | 1·179 | 1·069 |
Ca | 0·670 | 0·646 | 0·715 | 0·631 | 0·551 | 0·778 | 0·661 | 0·685 | 0·649 | 0·649 | 0·652 | 0·573 | 0·618 |
Sum | 3·982 | 3·983 | 3·983 | 3·975 | 3·990 | 3·973 | 3·990 | 3·965 | 3·966 | 3·972 | 3·962 | 3·987 | 3·983 |
*Abbreviations same as in Table 2.
† Numbers in parentheses are one standard deviation.
Mixture: | 60An40En | GS-11 | CMAS-15 |
Run: | 374-7 | 375-16 | 383-16 |
T (°C): | 1420 | 1410 | 1400 |
Phases*: | gl,sa,en,gt,di | gl,sa,gt,di | gl,gt,di,en |
Av. of: | 4 | 4 | 2 |
SiO2 | 44.25(0.22)† | 43.64(0.86) | 44.04 |
Al2O3 | 24.94(0.22) | 24.63(0.40) | 24.84 |
MgO | 25.52(0.40) | 25.83(0.56) | 25.39 |
CaO | 6.08(0.22) | 6.11(0.36) | 5.81 |
Sum | 100.79(1.06) | 100.21(2.18) | 100.08 |
Number of cations for 12 oxygens | |||
Si | 2.996 | 2.978 | 2.986 |
Al(IV) | 0.004 | 0.022 | 0.014 |
AI(VI) | 1.986 | 1.959 | 1.970 |
Mg | 2.575 | 2.627 | 2.622 |
Ca | 0.440 | 0.447 | 0.422 |
Sum | 8.001 | 8.033 | 8.014 |
Pyrope | 85 | 85 | 86 |
Grossularite | 15 | 15 | 14 |
Mixture: | 60An40En | GS-11 | CMAS-15 |
Run: | 374-7 | 375-16 | 383-16 |
T (°C): | 1420 | 1410 | 1400 |
Phases*: | gl,sa,en,gt,di | gl,sa,gt,di | gl,gt,di,en |
Av. of: | 4 | 4 | 2 |
SiO2 | 44.25(0.22)† | 43.64(0.86) | 44.04 |
Al2O3 | 24.94(0.22) | 24.63(0.40) | 24.84 |
MgO | 25.52(0.40) | 25.83(0.56) | 25.39 |
CaO | 6.08(0.22) | 6.11(0.36) | 5.81 |
Sum | 100.79(1.06) | 100.21(2.18) | 100.08 |
Number of cations for 12 oxygens | |||
Si | 2.996 | 2.978 | 2.986 |
Al(IV) | 0.004 | 0.022 | 0.014 |
AI(VI) | 1.986 | 1.959 | 1.970 |
Mg | 2.575 | 2.627 | 2.622 |
Ca | 0.440 | 0.447 | 0.422 |
Sum | 8.001 | 8.033 | 8.014 |
Pyrope | 85 | 85 | 86 |
Grossularite | 15 | 15 | 14 |
* Abbreviations same as in Table 2.
† Numbers in parentheses are one standard deviation.
Mixture: | 60An40En | GS-11 | CMAS-15 |
Run: | 374-7 | 375-16 | 383-16 |
T (°C): | 1420 | 1410 | 1400 |
Phases*: | gl,sa,en,gt,di | gl,sa,gt,di | gl,gt,di,en |
Av. of: | 4 | 4 | 2 |
SiO2 | 44.25(0.22)† | 43.64(0.86) | 44.04 |
Al2O3 | 24.94(0.22) | 24.63(0.40) | 24.84 |
MgO | 25.52(0.40) | 25.83(0.56) | 25.39 |
CaO | 6.08(0.22) | 6.11(0.36) | 5.81 |
Sum | 100.79(1.06) | 100.21(2.18) | 100.08 |
Number of cations for 12 oxygens | |||
Si | 2.996 | 2.978 | 2.986 |
Al(IV) | 0.004 | 0.022 | 0.014 |
AI(VI) | 1.986 | 1.959 | 1.970 |
Mg | 2.575 | 2.627 | 2.622 |
Ca | 0.440 | 0.447 | 0.422 |
Sum | 8.001 | 8.033 | 8.014 |
Pyrope | 85 | 85 | 86 |
Grossularite | 15 | 15 | 14 |
Mixture: | 60An40En | GS-11 | CMAS-15 |
Run: | 374-7 | 375-16 | 383-16 |
T (°C): | 1420 | 1410 | 1400 |
Phases*: | gl,sa,en,gt,di | gl,sa,gt,di | gl,gt,di,en |
Av. of: | 4 | 4 | 2 |
SiO2 | 44.25(0.22)† | 43.64(0.86) | 44.04 |
Al2O3 | 24.94(0.22) | 24.63(0.40) | 24.84 |
MgO | 25.52(0.40) | 25.83(0.56) | 25.39 |
CaO | 6.08(0.22) | 6.11(0.36) | 5.81 |
Sum | 100.79(1.06) | 100.21(2.18) | 100.08 |
Number of cations for 12 oxygens | |||
Si | 2.996 | 2.978 | 2.986 |
Al(IV) | 0.004 | 0.022 | 0.014 |
AI(VI) | 1.986 | 1.959 | 1.970 |
Mg | 2.575 | 2.627 | 2.622 |
Ca | 0.440 | 0.447 | 0.422 |
Sum | 8.001 | 8.033 | 8.014 |
Pyrope | 85 | 85 | 86 |
Grossularite | 15 | 15 | 14 |
* Abbreviations same as in Table 2.
† Numbers in parentheses are one standard deviation.
Mixture: | 60An40En | 80An20En | GS-0 | GS-8 | AFQ-28 | CMAS-18 |
Run: | 374-7 | 380-4 | 375-1 | 378-13* | 382-1 | 384-10 |
T (°C): | 1420 | 1450 | 1460 | 1390 | 1400 | 1440 |
Phases†: | gl,sa,en,gt,di | gl,sa,sp,an | gl,en,sa,di,(px) | gl,sa,an,en | gl,cor,an,sa | gl,sp,di,sa |
Av. of: | 7 | 2 | 3 | 1 | 3 | 2 |
SiO2 | 19·10(0·54)‡ | 15·36 | 18·95(0·15) | 19·07 | 17·03(0·33) | 19·16 |
Al2O3 | 56·66(0·85) | 62·58 | 56·65(0·43) | 56·58 | 59·56(0·81) | 55·80 |
MgO | 24·16(0·40) | 21·61 | 24·07(0·22) | 23·73 | 23·20(0·48) | 24·63 |
CaO | 0·50(0·11) | 0·58 | 0·50(0·08) | 0·43 | 0·32(0·06) | 0·50 |
Sum | 100·42(1·90) | 100·13 | 100·17(0·88) | 99·81 | 100·11(1·68) | 100·09 |
Number of cations for 20 oxygens | ||||||
Si | 2·182 | 1·764 | 2·172 | 2·190 | 1·954 | 2·197 |
Al(IV) | 3·818 | 4·236 | 3·828 | 3·810 | 4·046 | 3·803 |
AI(VI) | 3·816 | 4·230 | 3·825 | 3·852 | 4·006 | 3·743 |
Mg | 4·115 | 3·696 | 4·112 | 4·062 | 3·965 | 4·211 |
Ca | 0·060 | 0·070 | 0·060 | 0·050 | 0·038 | 0·060 |
Sum | 13·991 | 13·996 | 13·997 | 13·964 | 14·009 | 14·014 |
Mixture: | 60An40En | 80An20En | GS-0 | GS-8 | AFQ-28 | CMAS-18 |
Run: | 374-7 | 380-4 | 375-1 | 378-13* | 382-1 | 384-10 |
T (°C): | 1420 | 1450 | 1460 | 1390 | 1400 | 1440 |
Phases†: | gl,sa,en,gt,di | gl,sa,sp,an | gl,en,sa,di,(px) | gl,sa,an,en | gl,cor,an,sa | gl,sp,di,sa |
Av. of: | 7 | 2 | 3 | 1 | 3 | 2 |
SiO2 | 19·10(0·54)‡ | 15·36 | 18·95(0·15) | 19·07 | 17·03(0·33) | 19·16 |
Al2O3 | 56·66(0·85) | 62·58 | 56·65(0·43) | 56·58 | 59·56(0·81) | 55·80 |
MgO | 24·16(0·40) | 21·61 | 24·07(0·22) | 23·73 | 23·20(0·48) | 24·63 |
CaO | 0·50(0·11) | 0·58 | 0·50(0·08) | 0·43 | 0·32(0·06) | 0·50 |
Sum | 100·42(1·90) | 100·13 | 100·17(0·88) | 99·81 | 100·11(1·68) | 100·09 |
Number of cations for 20 oxygens | ||||||
Si | 2·182 | 1·764 | 2·172 | 2·190 | 1·954 | 2·197 |
Al(IV) | 3·818 | 4·236 | 3·828 | 3·810 | 4·046 | 3·803 |
AI(VI) | 3·816 | 4·230 | 3·825 | 3·852 | 4·006 | 3·743 |
Mg | 4·115 | 3·696 | 4·112 | 4·062 | 3·965 | 4·211 |
Ca | 0·060 | 0·070 | 0·060 | 0·050 | 0·038 | 0·060 |
Sum | 13·991 | 13·996 | 13·997 | 13·964 | 14·009 | 14·014 |
* Run results from Liu & Presnall (1990).
† Abbreviations same as in Table 2.
‡ Numbers in parentheses are one standard deviation.
Mixture: | 60An40En | 80An20En | GS-0 | GS-8 | AFQ-28 | CMAS-18 |
Run: | 374-7 | 380-4 | 375-1 | 378-13* | 382-1 | 384-10 |
T (°C): | 1420 | 1450 | 1460 | 1390 | 1400 | 1440 |
Phases†: | gl,sa,en,gt,di | gl,sa,sp,an | gl,en,sa,di,(px) | gl,sa,an,en | gl,cor,an,sa | gl,sp,di,sa |
Av. of: | 7 | 2 | 3 | 1 | 3 | 2 |
SiO2 | 19·10(0·54)‡ | 15·36 | 18·95(0·15) | 19·07 | 17·03(0·33) | 19·16 |
Al2O3 | 56·66(0·85) | 62·58 | 56·65(0·43) | 56·58 | 59·56(0·81) | 55·80 |
MgO | 24·16(0·40) | 21·61 | 24·07(0·22) | 23·73 | 23·20(0·48) | 24·63 |
CaO | 0·50(0·11) | 0·58 | 0·50(0·08) | 0·43 | 0·32(0·06) | 0·50 |
Sum | 100·42(1·90) | 100·13 | 100·17(0·88) | 99·81 | 100·11(1·68) | 100·09 |
Number of cations for 20 oxygens | ||||||
Si | 2·182 | 1·764 | 2·172 | 2·190 | 1·954 | 2·197 |
Al(IV) | 3·818 | 4·236 | 3·828 | 3·810 | 4·046 | 3·803 |
AI(VI) | 3·816 | 4·230 | 3·825 | 3·852 | 4·006 | 3·743 |
Mg | 4·115 | 3·696 | 4·112 | 4·062 | 3·965 | 4·211 |
Ca | 0·060 | 0·070 | 0·060 | 0·050 | 0·038 | 0·060 |
Sum | 13·991 | 13·996 | 13·997 | 13·964 | 14·009 | 14·014 |
Mixture: | 60An40En | 80An20En | GS-0 | GS-8 | AFQ-28 | CMAS-18 |
Run: | 374-7 | 380-4 | 375-1 | 378-13* | 382-1 | 384-10 |
T (°C): | 1420 | 1450 | 1460 | 1390 | 1400 | 1440 |
Phases†: | gl,sa,en,gt,di | gl,sa,sp,an | gl,en,sa,di,(px) | gl,sa,an,en | gl,cor,an,sa | gl,sp,di,sa |
Av. of: | 7 | 2 | 3 | 1 | 3 | 2 |
SiO2 | 19·10(0·54)‡ | 15·36 | 18·95(0·15) | 19·07 | 17·03(0·33) | 19·16 |
Al2O3 | 56·66(0·85) | 62·58 | 56·65(0·43) | 56·58 | 59·56(0·81) | 55·80 |
MgO | 24·16(0·40) | 21·61 | 24·07(0·22) | 23·73 | 23·20(0·48) | 24·63 |
CaO | 0·50(0·11) | 0·58 | 0·50(0·08) | 0·43 | 0·32(0·06) | 0·50 |
Sum | 100·42(1·90) | 100·13 | 100·17(0·88) | 99·81 | 100·11(1·68) | 100·09 |
Number of cations for 20 oxygens | ||||||
Si | 2·182 | 1·764 | 2·172 | 2·190 | 1·954 | 2·197 |
Al(IV) | 3·818 | 4·236 | 3·828 | 3·810 | 4·046 | 3·803 |
AI(VI) | 3·816 | 4·230 | 3·825 | 3·852 | 4·006 | 3·743 |
Mg | 4·115 | 3·696 | 4·112 | 4·062 | 3·965 | 4·211 |
Ca | 0·060 | 0·070 | 0·060 | 0·050 | 0·038 | 0·060 |
Sum | 13·991 | 13·996 | 13·997 | 13·964 | 14·009 | 14·014 |
* Run results from Liu & Presnall (1990).
† Abbreviations same as in Table 2.
‡ Numbers in parentheses are one standard deviation.
In Tables 4 and 5, it can be seen that the pyroxenes show a wide range of Al2O3 content from about 10% up to 14·5% for enstatite and 16% for diopside. We find no evidence for the existence of pigeonitic clinopyroxene in equilibrium with liquids well inside the FADS tetrahedron similar to the pyroxenes reported by Kushiro (1969) in equilibrium with liquids on the forsterite–diopside–silica face. Therefore, the primary phase volume for this phase must extend into the tetrahedron only a short distance, but we have no data that define its boundaries.
The sapphirine compositions are of some interest because this mineral is normally of metamorphic rather than igneous origin. Sapphirine shows solid solution by the substitution, R2+ + Si = 2R3+, mainly between the compositions 2MgO.2Al2O3.SiO2 (2:2:1) and 7MgO.9Al2O3.3SiO2 (7:9:3) (Gossner & Mussgnug, 1928). The compositions of sapphirines from this study are listed in Table 7 and plotted in Fig. 1. Except for the sapphirine composition in run 380-4, they show a SiO2-enriched and Al2O3-depleted character similar to the sapphirine compositions reported by Grew (1981) from pegmatites of Enderby Land, Antarctica.
Schreyer & Seifert (1969) suggested that increasing pressure extends the solid solution in sapphirine to less aluminous compositions. In a result consistent with this suggestion, Taylor (1973) found a restricted range of sapphirine compositions very close to the 2:2:1 composition in equilibrium with liquids in the MgO–Al2O3–SiO2 system at 1·5 GPa. Our data at 2·0 GPa show a wider range of sapphirine compositions approximately centered on the 2:2:1 composition but extending to both higher and lower Al2O3 contents (Fig. 1). In general, sapphirines that are higher in SiO2 and lower in Al2O3 are in equilibrium with liquids that are similarly silica enriched and alumina depleted. Other coexisting mineral phases include enstatite, garnet, diopside, anorthite, spinel, and corundum (Table 7).
PHASE RELATIONS
To facilitate visualization of the relatively complex liquidus phase relations, five diagrams (Figs 2–6) are used. Figure 2 shows the liquidus surface of the forsterite–anorthite–silica base of the FADS tetrahedron. This previously published diagram (Liu & Presnall, 1990) is repeated here because it is useful in clarifying the arrangement of the spinel, sapphirine, anorthite, and corundum primary phase volumes within the FADS tetrahedron that are partly obscured in the diagrams that follow.
Figure 3 shows the liquidus univariant lines and invariant points in a perspective view of the tetrahedron, and Fig. 4 shows a companion flow sheet of the univariant lines and invariant points, following the method of Chinner & Schairer (1962) and Schairer & Yoder (1969). To facilitate cross-referencing between Figs 3 and 4, the relative positions of the invariant points in the flow sheet (Fig. 4) are oriented as closely as possible to the arrangement in composition space shown in Fig. 3. The locations (Table 8) of five of the quaternary liquidus invariant points, F, R, A, C, and T, are determined by a combination of microprobe analysis of glasses and identification of primary phases for bracketing starting compositions. Given these five points, the existence and approximate locations of five additional invariant points are inferred (Table 8) and partly constrained by quenching data in Table 2. Lines I–M, A–M, and A–B are also partly constrained by glass analyses in Table 3 (runs 378-13, 374-7, and 380-4, respectively). As univarient lines inside the tetrahedran are straight within experimental uncertainty, each invariant point must lie within the tetrahedral composition volume formed by the four invariant points with which it is connected by univariant lines. Conformance to this requirement was confirmed algebraically for each invariant point, and in some cases, small adjustments to the invariant point compositions were required.
Point1 | T (°C) | Assemblage2 | An | Di | Fo | Q |
A3 | 1420 | gl+en+sa+di+gt | 59·6 | 7·7 | 19·8 | 12·9 |
B4 | 1390 | gl+sa+an+di+gt | 63·3 | 9·0 | 15·8 | 11·9 |
C5 | 1385 | gl+an+gt+di+en | 60·0 | 7·0 | 16·9 | 16·1 |
F6 | 1470 | gl+fo+en+di+sp | 50·0 | 15·7 | 28·7 | 5·6 |
M4 | 1395 | gl+en+an+gt+sa | 62·0 | 4·1 | 17·5 | 16·4 |
N4 | 1420 | gl+sp+di+sa+an | 68·0 | 11·4 | 12·4 | 8·2 |
R5 | 1455 | gl+en+di+sp+sa | 58·2 | 8·0 | 23·2 | 10·6 |
S4 | 1460 | gl+cor+sp+sa+an | 73 | 3 | 15 | 9 |
T3 | 1350 | gl+en+di+an+qz | 57·2 | 5·3 | 12·7 | 24·8 |
U4 | 1470 | gl+di+sp+cor+an | 71 | 17 | 7 | 5 |
Point1 | T (°C) | Assemblage2 | An | Di | Fo | Q |
A3 | 1420 | gl+en+sa+di+gt | 59·6 | 7·7 | 19·8 | 12·9 |
B4 | 1390 | gl+sa+an+di+gt | 63·3 | 9·0 | 15·8 | 11·9 |
C5 | 1385 | gl+an+gt+di+en | 60·0 | 7·0 | 16·9 | 16·1 |
F6 | 1470 | gl+fo+en+di+sp | 50·0 | 15·7 | 28·7 | 5·6 |
M4 | 1395 | gl+en+an+gt+sa | 62·0 | 4·1 | 17·5 | 16·4 |
N4 | 1420 | gl+sp+di+sa+an | 68·0 | 11·4 | 12·4 | 8·2 |
R5 | 1455 | gl+en+di+sp+sa | 58·2 | 8·0 | 23·2 | 10·6 |
S4 | 1460 | gl+cor+sp+sa+an | 73 | 3 | 15 | 9 |
T3 | 1350 | gl+en+di+an+qz | 57·2 | 5·3 | 12·7 | 24·8 |
U4 | 1470 | gl+di+sp+cor+an | 71 | 17 | 7 | 5 |
1Letters keyed to Figs 3–8.
2Abbrevations as in Table 2.
3Composition based on analysis of glass at the invariant point.
4Estimated composition and temperature.
6From Walter & Presnall (1994).
Point1 | T (°C) | Assemblage2 | An | Di | Fo | Q |
A3 | 1420 | gl+en+sa+di+gt | 59·6 | 7·7 | 19·8 | 12·9 |
B4 | 1390 | gl+sa+an+di+gt | 63·3 | 9·0 | 15·8 | 11·9 |
C5 | 1385 | gl+an+gt+di+en | 60·0 | 7·0 | 16·9 | 16·1 |
F6 | 1470 | gl+fo+en+di+sp | 50·0 | 15·7 | 28·7 | 5·6 |
M4 | 1395 | gl+en+an+gt+sa | 62·0 | 4·1 | 17·5 | 16·4 |
N4 | 1420 | gl+sp+di+sa+an | 68·0 | 11·4 | 12·4 | 8·2 |
R5 | 1455 | gl+en+di+sp+sa | 58·2 | 8·0 | 23·2 | 10·6 |
S4 | 1460 | gl+cor+sp+sa+an | 73 | 3 | 15 | 9 |
T3 | 1350 | gl+en+di+an+qz | 57·2 | 5·3 | 12·7 | 24·8 |
U4 | 1470 | gl+di+sp+cor+an | 71 | 17 | 7 | 5 |
Point1 | T (°C) | Assemblage2 | An | Di | Fo | Q |
A3 | 1420 | gl+en+sa+di+gt | 59·6 | 7·7 | 19·8 | 12·9 |
B4 | 1390 | gl+sa+an+di+gt | 63·3 | 9·0 | 15·8 | 11·9 |
C5 | 1385 | gl+an+gt+di+en | 60·0 | 7·0 | 16·9 | 16·1 |
F6 | 1470 | gl+fo+en+di+sp | 50·0 | 15·7 | 28·7 | 5·6 |
M4 | 1395 | gl+en+an+gt+sa | 62·0 | 4·1 | 17·5 | 16·4 |
N4 | 1420 | gl+sp+di+sa+an | 68·0 | 11·4 | 12·4 | 8·2 |
R5 | 1455 | gl+en+di+sp+sa | 58·2 | 8·0 | 23·2 | 10·6 |
S4 | 1460 | gl+cor+sp+sa+an | 73 | 3 | 15 | 9 |
T3 | 1350 | gl+en+di+an+qz | 57·2 | 5·3 | 12·7 | 24·8 |
U4 | 1470 | gl+di+sp+cor+an | 71 | 17 | 7 | 5 |
1Letters keyed to Figs 3–8.
2Abbrevations as in Table 2.
3Composition based on analysis of glass at the invariant point.
4Estimated composition and temperature.
6From Walter & Presnall (1994).
Five univariant lines and one invariant point (S, Fig. 4) are concealed behind the opaque faceted surface partially bounded by the points, E, G, I, J, L, V, and W in Fig. 3. The divariant surfaces making up this composite opaque surface are those defined by the primary phase volumes for spinel, sapphirine, garnet, anorthite and corundum where they meet the forsterite, enstatite, diopside, and high quartz primary phase volumes (compare Figs 2 and 3). One of the concealed univariant lines joins points B and M and produces a garnet primary phase volume in the shape of a tetrahedron (see inset for Fig. 3). The other four concealed univariant lines extend from invariant point S (Fig. 4). Two of these lines connect S to invariant points N and U on the opaque surface and the other two connect S to points H and K in Fig. 2.
The locations of some of the phase boundaries shown in Fig. 3 are poorly constrained but representation of these boundaries as dashed lines has been avoided, to reduce confusion. The boundary surface between the high quartz volume and other volumes is constrained by data only at the forsterite–silica edge (Chen & Presnall, 1975), along line J–L (Liu & Presnall, 1990), and at point T (this study). The limit of the high quartz volume on the diopside–silica edge and the location of the diopside–corundum–high quartz piercing point on the right rear face, diopside–anorthite–silica, are taken from the preliminary diagram of Clark et al. (1962), although they listed no data. Estimated positions for the limits of the corundum volume at points W and L are taken, respectively, from the unreversed results of Presnall et al. (1978) and Liu & Presnall (1990), but these results are tentative because of sluggish reactions involving corundum. Location of a probable invariant point involving high quartz, anorthite, corundum, and diopside is unknown and indicated by a question mark.
REACTIONS AT INVARIANT POINTS
Presnall (1986) described an algebraic method for determining whether an isobaric liquidus invariant point is a peritectic or eutectic point and the direction of decreasing temperature of a liquidus univariant line as it meets an invariant point. The procedure requires only a knowledge of the compositions of all the phases in equilibrium at the invariant point. For an n-component system, a balanced chemical equation is written involving all the n + 1 phases in equilibrium. Liquidus univariant lines that include the complete phase assemblage on the side of the equation not containing the liquid phase decrease in temperature away from the invariant point. All the remaining univariant lines decrease in temperature toward the invariant point. For example, at a simple ternary eutectic in which the reaction among phases A, B, C, and liquid is A + B + C = liquid, none of the phase assemblages for univariant lines coming into the eutectic contain the complete assemblage A + B + C. One of these crystalline phases will always be absent. Therefore, all of the three univariant lines decrease in temperature toward the eutectic, as is well known from classical geometrical considerations.
We use this method to characterize the invariant points and univariant lines in Figs 3 and 4. In the calculations of the reactions at invariant points, pure end-member compositions are assumed for anorthite, corundum, forsterite, quartz, and spinel. For enstatite, diopside, garnet, and sapphirine, analyzed compositions (Tables 4–7) are used. For cases in which analyzed compositions are not available for crystalline phases exactly at an invariant point, the composition of the same phase in a crystal–liquid assemblage close to the invariant point is used. Liquid compositions at invariant points are taken from Table 8. The reactions at each invariant point are listed in Table 9, and directions of decreasing temperature along univariant lines in Figs 3–4 are assigned according to these reactions. Of the five determined invariant points, F, R, A, C, and T, only T is a eutectic. All the others are peritectics (Figs 3 and 4).
Point* | Reactions based on phase composition data† |
F | 23 en + 68 di + 9 sp = 84 liq + 16 fo |
R | 37 di + 63 sa = 47 liq + 40 sp + 13 en |
A | 100 gt = 21 liq + 27 sa + 55 en + 18 di |
C | 1 di + 59 en + 41 an = 43 liq + 57 gt |
T | 18 di + 21 qz + 15 en + 47 an = 100 liq |
Inferred reactions‡ | |
B | di + an + gt = liq + sa |
M | an + gt = liq + sa + en |
N | sa + an + di = liq + sp |
S | sa + an = liq + cor + sp |
U | di + cor = liq + an + sp |
Point* | Reactions based on phase composition data† |
F | 23 en + 68 di + 9 sp = 84 liq + 16 fo |
R | 37 di + 63 sa = 47 liq + 40 sp + 13 en |
A | 100 gt = 21 liq + 27 sa + 55 en + 18 di |
C | 1 di + 59 en + 41 an = 43 liq + 57 gt |
T | 18 di + 21 qz + 15 en + 47 an = 100 liq |
Inferred reactions‡ | |
B | di + an + gt = liq + sa |
M | an + gt = liq + sa + en |
N | sa + an + di = liq + sp |
S | sa + an = liq + cor + sp |
U | di + cor = liq + an + sp |
† Liquid compositions from Table 8, mineral compositions from Tables 4–7 (reaction R, run 375-1; reaction A, run 374-7; reaction C, run 383-16; reaction T, run 379-16). Reactions F [data from Walter & Presnall (1994)] and A use phase composition data from single runs containing all the phases at the invariant point. Other reactions use crystalline phase compositions in equilibrium with liquids near the invariant point and are therefore less accurate. For reactions A and T, the composition of the liquid used deviates slightly from the composition in the single run as a result of constraints from other runs.
‡ Phase composition data are used to determine the form of these reactions, but coefficients are not shown because the compositions of the invariant point liquids and some of the crystalline phases are not well constrained. Because the coefficients are uncertain, it is possible that even the form of some of these reactions may be incorrect.
Point* | Reactions based on phase composition data† |
F | 23 en + 68 di + 9 sp = 84 liq + 16 fo |
R | 37 di + 63 sa = 47 liq + 40 sp + 13 en |
A | 100 gt = 21 liq + 27 sa + 55 en + 18 di |
C | 1 di + 59 en + 41 an = 43 liq + 57 gt |
T | 18 di + 21 qz + 15 en + 47 an = 100 liq |
Inferred reactions‡ | |
B | di + an + gt = liq + sa |
M | an + gt = liq + sa + en |
N | sa + an + di = liq + sp |
S | sa + an = liq + cor + sp |
U | di + cor = liq + an + sp |
Point* | Reactions based on phase composition data† |
F | 23 en + 68 di + 9 sp = 84 liq + 16 fo |
R | 37 di + 63 sa = 47 liq + 40 sp + 13 en |
A | 100 gt = 21 liq + 27 sa + 55 en + 18 di |
C | 1 di + 59 en + 41 an = 43 liq + 57 gt |
T | 18 di + 21 qz + 15 en + 47 an = 100 liq |
Inferred reactions‡ | |
B | di + an + gt = liq + sa |
M | an + gt = liq + sa + en |
N | sa + an + di = liq + sp |
S | sa + an = liq + cor + sp |
U | di + cor = liq + an + sp |
† Liquid compositions from Table 8, mineral compositions from Tables 4–7 (reaction R, run 375-1; reaction A, run 374-7; reaction C, run 383-16; reaction T, run 379-16). Reactions F [data from Walter & Presnall (1994)] and A use phase composition data from single runs containing all the phases at the invariant point. Other reactions use crystalline phase compositions in equilibrium with liquids near the invariant point and are therefore less accurate. For reactions A and T, the composition of the liquid used deviates slightly from the composition in the single run as a result of constraints from other runs.
‡ Phase composition data are used to determine the form of these reactions, but coefficients are not shown because the compositions of the invariant point liquids and some of the crystalline phases are not well constrained. Because the coefficients are uncertain, it is possible that even the form of some of these reactions may be incorrect.
DIOPSIDE SATURATION SURFACE
Figures 5 and 6 show the diopside saturation surface (a mosaic of divariant surfaces that define the diopside primary phase volume) projected onto the base, forsterite–anorthite–silica, of the FADS tetrahedron from the diopside apex. Figure 5 shows temperature contours and Fig. 6 shows contours of percent CaMgSi2O6 on the surface. These diagrams provide a different way of viewing some of the more important phase relations in Fig. 3 and are used here to clarify the experimental control on several of the phase boundaries. It is not possible to use these diagrams in a rigorous way to determine diopside-saturated crystallization paths because the point of projection, pure CaMgSi2O6, is not the same as the diopside compositions in equilibrium with liquids on the surface. However, these diagrams are useful for illustrating crystallization paths deduced algebraically, as discussed below.
Figure 7 shows an expanded view of the boundary lines in the upper part of Figs 5 and 6. The position of point F is from the study by Walter & Presnall (1994) and is based on a glass analysis of a run containing all the phases at the invariant point (forsterite, enstatite, diopside, spinel, liquid). Similarly, the location of point A is based on a glass analysis of a run containing sapphirine, enstatite, garnet, diopside and liquid (run 374-7, Table 3). Glass analyses are also shown for points along the R–A and C–T lines. To reduce deviations of analyzed glass compositions from the R–A line, point A is shown slightly to one side of the glass analysis that locates it. Point T is bracketed by glass analyses (Table 3) on the univariant lines C–T (runs 375-17 and 383-17) and J–T (runs 378-12 and 380-6, not plotted in Fig. 7), and by two runs (379-16 and 379-17) that show all the phases at T (anorthite, enstatite, quartz, diopside, liquid). Also, Table 2 shows that quartz, enstatite, diopside, and anorthite appear simultaneously at the liquidus for mixture CMAS-12. Therefore, we locate point T between the glass analyses for 379-16 and 379-17, and slightly toward the starting composition, CMAS-12.
HIGH-PRESSURE FRACTIONAL CRYSTALLIZATION OF BASALT
In Figs 3–6, point F is a model basalt that would be produced from a spinel lherzolite (olivine + enstatite + diopside + spinel) at 2·0 GPa. If F were a eutectic, fractional crystallization at 2 GPa would not yield any evolved liquids and F would crystallize completely to a rock of its own composition. However, as F is a peritectic, some kind of fractional crystallization path must occur. Also, all other invariant points down-temperature from F are peritectics except for T, which is a eutectic. Therefore, the fractional crystallization path would be extensive. Simple inspection of the directions of decreasing temperature along the univariant lines suggests that the liquid would move along the path, F–R–A–C–T, but that a deviation might occur between A and C toward either B or M. By using the algebraic procedures of Presnall (1986, 1991), it has been shown elsewhere (Presnall, 1999) that the liquid does, in fact, move by fractional crystallization along the F–R–A–C–T path, and that the liquid path leaving A moves not along the A–C line but across the A–B–C surface as garnet and diopside crystallize. When the liquid reaches the B–C line, it moves down this line to C as garnet, diopside, and anorthite crystallize. As none of the univariant lines along the path show a reaction relationship, all of the phases in equilibrium with liquids on each line crystallize with decreasing temperature.
In Table 10, the composition of model basalt F is shown along with the final residual liquid produced at T and the final liquid that would occur if the fractional crystallization had occurred at 1 atm. At both pressures, SiO2 is strongly enriched and MgO is strongly depleted. The Al2O3 content is slightly depleted at 1 atm and slightly enriched at 2 GPa, an effect caused by the shrinkage of the anorthite volume at higher pressures (Liu & Presnall, 1990).
Starting | Final liquid | Final liquid | |
liquid* | (1 atm)† | (2 GPa)‡ | |
SiO2 | 48·2 | 62·5 | 57·9 |
Al2O3 | 18·3 | 15·0 | 21·0 |
MgO | 19·3 | 8·6 | 8·3 |
CaO | 14·2 | 13·8 | 12·9 |
Starting | Final liquid | Final liquid | |
liquid* | (1 atm)† | (2 GPa)‡ | |
SiO2 | 48·2 | 62·5 | 57·9 |
Al2O3 | 18·3 | 15·0 | 21·0 |
MgO | 19·3 | 8·6 | 8·3 |
CaO | 14·2 | 13·8 | 12·9 |
† Composition of enstatite–diopside–anorthite–tridymite eutectic (Longhi, 1987).
Starting | Final liquid | Final liquid | |
liquid* | (1 atm)† | (2 GPa)‡ | |
SiO2 | 48·2 | 62·5 | 57·9 |
Al2O3 | 18·3 | 15·0 | 21·0 |
MgO | 19·3 | 8·6 | 8·3 |
CaO | 14·2 | 13·8 | 12·9 |
Starting | Final liquid | Final liquid | |
liquid* | (1 atm)† | (2 GPa)‡ | |
SiO2 | 48·2 | 62·5 | 57·9 |
Al2O3 | 18·3 | 15·0 | 21·0 |
MgO | 19·3 | 8·6 | 8·3 |
CaO | 14·2 | 13·8 | 12·9 |
† Composition of enstatite–diopside–anorthite–tridymite eutectic (Longhi, 1987).
The most important result of this comparison is the strong SiO2 enrichment at 2 GPa. This result is in sharp contrast to early suggestions that enhanced crystallization of orthopyroxene from a tholeiitic basalt at high pressures leads to the production of an alkalic basalt (O’Hara & Mercy, 1963; Green & Ringwood, 1964, 1967; O’Hara, 1965; Kushiro, 1979). In Figs 3, 5, and 6, it can be seen that the initial part of the liquid path from F is characterized by crystallization of enstatite, diopside, and spinel as the liquid becomes enriched in SiO2. The reason for this enrichment is the crystallization of spinel, a mineral observed by Green & Ringwood (1967) at 1·24 and 1·35 GPa, but not at higher pressures, and not used in their fractionation calculations. O’Hara (1965) also did not discuss the role of spinel and based his conclusions about enhanced crystallization of orthopyroxene at intermediate pressures mostly on inferred phase relations.
In Fig. 3, the spinel field at 2 GPa is very large and cuts across the forsterite–anorthite join on the base of the FADS tetrahedron, but when anorthite is replaced by albite, the spinel field is absent (Kushiro, 1968). In this case, Kushiro (1979) pointed out that fractional crystallization of forsterite and enstatite drives tholeiitic compositions across the forsterite–albite join to alkalic compositions. Spinel does not crystallize. The key issue is whether or not spinel crystallizes from natural basaltic magmas for which the plagioclase that crystallizes is intermediate in composition between albite and anorthite. If it does, then the strong SiO2 enrichment trend described here would occur. If it does not, then alkalic residual liquids would be expected. The issue is unresolved by existing experimental data, but it appears likely that at 2 GPa, parental tholeiitic magmas high in Na2O would not crystallize spinel and would yield alkalic residual liquids. Those low in Na2O would crystallize spinel and produce SiO2-enriched residual liquids.
If our results in the CMAS system apply to natural magmas at subduction zones, then basalts generated at about 2 GPa in the mantle wedge and fractionally crystallized near the depth of generation would produce Al2O3- and SiO2-enriched residual liquids similar in composition to andesites, even in the absence of volatiles. We do not advocate completely anhydrous fractionation in the mantle wedge, and Stern & Wyllie (1978) have presented data indicating that such fractionation does not exactly duplicate calc-alkaline fractionation trends at subduction zones. Nevertheless, it is interesting that the effects of high-pressure anhydrous fractionation appear in a general way to reinforce the effects of hydrous fractionation involving amphibole (Sisson & Grove, 1993).
ECLOGITES AND GARNET CLINOPYROXENITES
Rocks consisting almost entirely of garnet and clinopyroxene (eclogite if the clinopyroxene is jadeitic, garnet clinopyroxenite if it is not) are found as xenoliths in basaltic and kimberlitic eruptions (Shervais et al., 1973; Irving, 1974; Griffin et al., 1984; Sen, 1988; Neal et al., 1990; Fung & Haggerty, 1995; Snyder et al., 1997) and as bodies tectonically emplaced in orogenic zones (Dawson & Carswell, 1990). Our data bear on the common suggestion that many eclogites and garnet clinopyroxenites are magmatic cumulates. Garnet and diopside crystallize from liquids on the A–B–C surface (Figs 3, 5, and 6). The proportions of diopside and garnet that crystallize can be determined using the algebraic procedures given by Presnall (1986, 1991). A determinant is set up using the compositions of the liquids at A, B, and C (Table 8) and the garnet and diopside compositions in run 374-7 (Fig. 7, Tables 5 and 6). The resulting equation is 100A = 9di + 8gt + 31B + 52C. The coefficients in this equation show two things. First, as liquid A crystallizes, the liquid moves across the A–B–C surface to a point on the B–C line at the composition, 37% B, 63% C. Second, the proportions of minerals that crystallize are 54% diopside, 46% garnet. Thus, the phase relations support formation of at least some garnet pyroxenites and eclogites as igneous cumulates crystallized from magmas intermediate between tholeiitic basalt and andesite.
The size of the garnet primary phase volume, A–B–C–M (Fig. 3), is very small at this pressure and it increases in size with pressure. This can be seen by comparing the garnet volume in Fig. 3 with that found at 3 GPa by Milholland & Presnall (1998). Therefore, as pressure decreases from 2 GPa, the garnet volume shrinks as points A, B, C, and M converge to an invariant point in pressure–temperature space at which garnet, sapphirine, anorthite, diopside, enstatite and liquid are in equilibrium. The pressure of this invariant point is uncertain but it is probably only slightly below 2 GPa, at about 1·8–1·9 GPa. It defines the lower pressure limit for the formation of cumulate model eclogites and garnet clinopyroxenites in the CMAS system. This pressure is useful as an approximate guide for natural cumulates, but it should be used with caution because of the presence of additional components, in particular FeO and Na2O.
O’Hara & Yoder (1967) suggested that crystallization of garnet and clinopyroxene from picritic magmas provides a mechanism for producing alkalic residual liquids from tholeiitic parents. Subsequently, O’Hara (1968) proposed that eclogite fractionation occurs from an alkalic magma. Our data, which locate the garnet–diopside surface well within the tholeiitic portion of the simplified basalt tetrahedron, do not support these suggestions at pressures in the vicinity of 2 GPa. Addition of Na2O would be expected to extend the garnet–diopside surface toward alkalic compositions but data are not available for a quantitative discussion of this effect. Also, the garnet–diopside surface expands with pressure (Milholland & Presnall, 1998), which makes eclogite fractionation from alkalic magmas more likely at higher pressures. Thus, some cumulate garnet pyroxenites and eclogites may be crystallized from alkalic magmas at higher pressures whereas others may be crystallized from moderately fractionated tholeiitic magmas at lower pressures.
IGNEOUS SAPPHIRINE
In our earlier paper on the liquidus of the anorthite–forsterite–silica join (Liu & Presnall, 1990), we addressed two issues regarding the acceptance of sapphirine as an igneous mineral capable of crystallizing from normal mafic to modestly fractionated magmas. First, there is an apparent discrepancy between our model-system results indicating that sapphirine crystallizes from mildly mafic melts (Fig. 3) and the results of crystallization experiments on natural compositions, in which sapphirine has never been found. Second, we were aware at that time of only one report (S. A. Morse, personal communication, 1988; see also Morse & Talley, 1971) of sapphirine believed to be the result of crystallization from a mafic magma. In another occurrence, sapphirine has crystallized from a pegmatite in Enderby Land, Antarctica (Grew, 1981). In all other cases of which we are aware, sapphirine occurs in rocks that are described as metamorphic. In some of these occurrences, the sapphirine may have originally formed from a magma, but this would generally be impossible to determine with any assurance. The situation on both of these issues has not changed and we refer the reader to our earlier discussion (Liu & Presnall, 1990, pp. 740-741).
In the FADS tetrahedron, sapphirine occurs at the liquidus at 2 and 3 GPa (Milholland & Presnall, 1998). It is not present at 1 atm (Presnall et al., 1979) and it was not observed at 1·0 GPa either on the forsterite–anorthite–silica base of the FADS tetrahedron (Liu & Presnall, 1990) or in some preliminary experiments performed in Presnall’s laboratory within the tetrahedron (P. Thy, personal communication, 1982). The size of the sapphirine primary phase volume is smaller at 3 than at 2 GPa. Therefore, sapphirine appears to have both an upper (>3 GPa) and lower (∼1·1–1·5 GPa) pressure stability limit at the liquidus for compositions within the FADS tetrahedron. This limited range of stability combined with the short interval over which sapphirine would crystallize even at 2 GPa (Fig. 3) and the tendency of high-pressure phenocrysts to dissolve on decompression severely reduce the expectation that a relict phenocryst of sapphirine would ever be brought to the surface in a lava.
Sapphirine pyroxenite from Delegate, Australia
The best hope for survival of sapphirine crystallized from a magma at high pressure would be in a cumulate xenolith brought rapidly to the surface by a subsequent eruption. Even this type of occurrence would be expected to be uncommon because of the limited range of pressure over which sapphirine is stable at the liquidus and its narrow crystallization interval (Fig. 3). A xenolith from the Delegate breccia pipes in Australia is especially interesting (Griffin & O’Reilly, 1986) and we have already discussed this xenolith in a preliminary way (Liu & Presnall, 1990). Griffin & O’Reilly (1986) interpreted this layered xenolith, which consists of clinopyroxene, plagioclase, garnet, and sapphirine, to be the result of recrystallization of an original clinopyroxene + spinel + plagioclase cumulate assemblage. More generally, Lovering & White (1969) and Irving (1974) both suggested that other layered xenoliths from the Delegate locality were formed as cumulates.
In Figs 3–6, the liquid at invariant point B is in equilibrium with diopside, anorthite, garnet, and sapphirine, the identical assemblage found in the Delegate xenolith. In addition, the Al2O3 contents of diopside in runs 375-16 and 380-12 (Table 5) are 15·5 and 16·1%, respectively. Both of these diopsides are in equilibrium with liquids close to B. These Al2O3 contents are very close to the unusually high value of 16·97% reported for the Delegate xenolith (Griffin & O’Reilly, 1986). In addition, the sapphirine in run 380-4, which is in equilibrium with a liquid close to B, has a composition significantly toward the 7:9:3 (MgO:Al2O3:SiO2) composition from the other analyzed sapphirines clustering near the 2:2:1 composition (Fig. 1). This compares favorably with the Delegate sapphirine, which also lies between the 7:9:3 and 2:2:1 compositions but closer to 7:9:3 (Fig. 1). All of these similarities, combined with the absence of any petrographic evidence for an earlier mineralogy (Griffin & O’Reilly, 1986), lead us to propose that the Delegate xenolith is not recrystallized from an earlier cumulate assemblage. Instead, we believe that our experimental data provide strong evidence that the mineralogy as it exists at present is, in fact, the original cumulate assemblage.
At a pressure slightly below 2·0 GPa, perhaps 1·9–1·8 GPa, it was pointed out above that isobaric invariant points A, B, C, and M collapse to a single invariant point in P–T space. This establishes an approximate lower limit for the pressure at which the mineral assemblages in the Delegate xenolith could crystallize from a melt. Other components, most importantly iron oxide and Na2O, may alter this result slightly. However, there is not very much room for argument based on this chemical difference because 93% of the composition of the xenolith is represented in the CMAS system. Finally, we note that the phase relations indicate a melt in equilibrium with the minerals in this xenolith intermediate between a model tholeiitic basalt (point F) and a more fractionated magma with similarities to andesite (point T).
Sapphirine norite, Wilson Lake, Labrador, Canada
S. A. Morse (personal communications, 1988 and 1998) has informed us of a possible igneous occurrence of sapphirine at Wilson Lake, Labrador, Canada. The rocks consist of hypersthene, plagioclase, and magnetite with either sapphirine or spinel. In his communication, he indicates that ‘Some of the rocks are foliated but many are granular and unfoliated. The sapphirine is present in amounts up to 20+% and is often seen as independent grains in clusters with hypersthene + oxide, locally rimming these. These rocks appear to be aluminous metabasites, or in other words, reasonable candidates for sapphirine norites. Sapphirine has the same textural status as hypersthene when abundant. From the essentially gabbroic (s.l.) compositions and textures, they could be very credible examples of igneous sapphirine.’
In Figs 3 and 4, liquids along the univariant line M–I are in equilibrium with sapphirine, enstatite, and anorthite, essentially the assemblage observed by Morse. As we have already noted, sapphirine has not been found at the liquidus at 1·0 GPa, so this gives a rough lower limit for the pressure at which the Wilson Lake sapphirine norite crystallized, assuming it is igneous. At 2·0 GPa, liquids in equilibrium with the assemblage enstatite + anorthite + spinel (comparable with hypersthene + plagioclase + spinel in the Wilson Lake occurrence) do not exist but would be expected at lower pressures as a result of contraction of the garnet and sapphirine volumes. This suggests a rough upper limit of 2·0 GPa for crystallization of the Wilson Lake norites. As with the sapphirine pyroxenite from Delegate, the magma from which this rock crystallized would be intermediate in composition between basalt and andesite.
SUMMARY OF CONCLUSIONS
Liquidus phase relations at 2·0 GPa in the forsterite–anorthite–diopside–silica tetrahedron within the system CaO–MgO–Al2O3–SiO2 indicate the following conclusions:
Fractional crystallization of model basalt at 2·0 GPa leads to the production of a final residual liquid enriched in SiO2 and Al2O3, and depleted in MgO, a composition with similarities to andesite. This result suggests that early experimental results indicating a fractionation trend from tholeiitic to alkalic basalt in this pressure range may apply only for tholeiitic parental magmas high in Na2O that do not crystallize spinel. The andesitic CMAS trend may apply only to tholeiitic parental magmas low in Na2O that crystallize spinel.
The approximate lower pressure limit for the formation of garnet pyroxenites and eclogites as cumulates is 1·8–1·9 GPa.
The lower pressure limit for crystallization of sapphirine at the liquidus in the CMAS system is estimated to be about 1·1–1·5 GPa and the upper pressure limit is >3 GPa.
Sapphirine crystallizes from modestly fractionated liquids intermediate in composition between a model basalt and a model andesite.
The assemblage sapphirine + garnet + clinopyroxene + plagioclase in a layered xenolith from Delegate, Australia (Griffin & O’Reilly, 1986) is the same assemblage as that in equilibrium with a liquidus invariant point in the CMAS system. We suggest that this is a cumulate assemblage formed at a pressure of at least 1·8–1·9 GPa.
Norites at Wilson Lake, Labrador, Canada (S. A. Morse, personal communication, 1988 and 1998) have the assemblage sapphirine + hypersthene + plagioclase + magnetite, with either sapphirine or spinel. If these are igneous asemblages, phase relations in the CMAS system suggest an origin in the pressure range 1–2 GPa.
*Corresponding author.
This study was carried out at the University of Texas at Dallas as part of the Ph.D. dissertation of Liu. Financial support was provided by National Science Foundation Grants EAR 84-18685 and EAR-9725900 and Texas Advanced Research Program Grant 3927 to Presnall. Liu received support from the National Science Council of Taiwan (NSC87-2116-M-003-004) during manuscript preparation. Presnall thanks Professor I. Kushiro and the Institute for Study of the Earth’s Interior, Okayama University, Misasa, Japan, for financial support and a fine working environment during manuscript preparation. This paper is Contribution 897, Department of Geosciences, University of Texas at Dallas.
References
Arima, M. & Barnett, R. L. (
Boyd, F. R. & England, J. L. (
Caporuscio, F. A. & Morse, S. A. (
Cawthorne, R. G., Ford, C. E., Biggar, G. M., Bravo, M. S. & Clark, D. B. (
Chen, C.-H. & Presnall, D. C. (
Chinner, G. A. & Schairer, J. F. (
Christy, A. G. (
Christy, A. G. & Harley, S. L. (
Clark, S. P., Jr, Schairer, J. F. & de Neufville, J. (
Currie, K. L. & Gittins, J. (
Dasgupta, S. & Ehl, J. (
Dawson, J. B. & Carswell, D. A. (
Dawson, B., Harley, S. L., Rudnick, R. L. & Ireland, T. R. (
Droop, G. T. R. (
Edwin, G. & Daniel, K. (
Friend, C. R. L., Janardhan, A. S. & Shadakshara, S. N. (
Fung, A. T. & Haggerty, S. E. (
Gossner, B. & Mussgnug, F. (
Goscombe, B. (
Grant, S. M. (
Green, D. H. (
Green, D. H. & Ringwood, A. E. (
Green, D. H. & Ringwood, A. E. (
Grew, E. S. (
Grew, E. S. (
Grew, E. S., Pertsev, N. N., Yates, M. G., Christy, A. G., Marquez, N. & Chernosky, J. V. (
Griffin, W. L. & O’Reilly, S. Y. (
Griffin, W. L., Wass, S. Y. & Hollis, J. D. (
Guiraud, M., Kienast, J. R. & Rahmani, A. (
Harley, S. L. (
Irving, A. J. (
Jaques, A. L. & Green, D. H. (
Jaques, A. L. & Green, D. H. (
Johansson, L. & Moller, C. (
Kihle, J. & Bucher-Nurminen, K. (
Kushiro, I. (
Kushiro, I. (
Kushiro, I. (
Liati, A. & Seidel, E. (
Liu, T.-C. & Presnall, D. C. (
Longhi, J. (
Lovering, J. F. & White, A. J. R. (
Meyer, H. O. A. & Brookins, D. G. (
Milholland, C. S. & Presnall, D. C. (
Mohan, A. & Windley, B. F. (
Morse, S. A. & Talley, J. H. (
Motoyoshi, Y. & Hensen, B. J. (
Neal, C. R., Taylor, L. A., Davidson, J. P., Holden, P., Halliday, A. N., Nixon, P. H., Paces, J. B., Clayton, R. N. & Mayeda, T. K. (
O’Hara, M. J. (
O’Hara, M. J. (
O’Hara, M. J. & Mercy, E. L. P. (
O’Hara, M. J. & Yoder, H. S., Jr (
Presnall, D. C. (
Presnall, D. C. (
Presnall, D. C. (
Presnall, D. C. (
Presnall, D. C. (
Presnall, D. C., Dixon, J. R., O’Donnell, T. H. & Dixon, S. A. (
Presnall, D. C., Dixon, S. A., Dixon, J. R., O’Donnell, T. H., Brenner, N. L., Schrock, R. L. & Dycus, D. W. (
Presnall, D. C., Simmons, C. L. & Porath, H. (
Raith, M., Karmakar, S. & Brown, M. (
Schairer, J. F. & Yoder, H. S., Jr (
Schreyer, W. & Seifert, F. (
Sen, G. (
Sen, G. & Presnall, D. C. (
Shervais, J. W., Wilshire, H. G. & Schwarzman, E. C. (
Sisson, T. W. & Grove, T. L. (
Snyder, G. A., Taylor, L. A., Crozaz, G., Halliday, A. N., Beard, B. L., Sobolev, V. N. & Sobolev, N. V. (
Stern, C. R. & Wyllie, P. J. (
Taylor, H. C. J. (
Tenthorey, E. A., Ryan, J. C. & Snow, E. A. (
Walter, M. J. & Presnall, D. C. (
Windley, B. F., Ackermand, D. & Herd, R. K. (