Phase Diagrams Continued
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Phase Diagrams Phase Diagrams Continued Continued 1557 1557 Mg Mg 2 SiO SiO 4 20 20 40 40 60 60 80 80 SiO SiO 2 1400 1400 1600 1600 1800 1800 2000 2000 1713 1713 T T o C C MgSiO MgSiO 2 1543 1470 Forsterite Forsterite + Enstatite + Enstatite Liquid + Liquid + Forsterite Forsterite 1695 Enstatite + Tridymite Enstatite + Cristobalite Cristobalite + Liquid Two Liquids Liquid Wt.% X Wt.% X 2 o n c p T T M M Anorthite Anorthite Forsterite Forsterite
description
Anorthite. n. Liquid. 2000. o. p. Two Liquids. 1800. 1713. T o C. 1695. Liquid +. Forsterite. M. Cristobalite + Liquid. 1600. 1557. 1543. T. c. Enstatite + Cristobalite. Forsterite. 1470. + Enstatite. Enstatite + Tridymite. 1400. 20. 60. SiO 2. 80. 40. Forsterite. - PowerPoint PPT Presentation
Transcript of Phase Diagrams Continued
Phase Diagrams ContinuedPhase Diagrams Continued
15571557
MgMg22SiOSiO44
2020 4040 6060 8080 SiOSiO22
14001400
16001600
18001800
20002000
17131713T T ooC C
MgSiOMgSiO22
1543
1470ForsteriteForsterite+ Enstatite+ Enstatite
Liquid +Liquid + ForsteriteForsterite
1695
Enstatite + Tridymite
Enstatite + Cristobalite
Cristobalite + Liquid
Two Liquids
Liquid
Wt.% XWt.% X22
o
n
c
p
TT
MM
AnorthiteAnorthite
ForsteriteForsterite
- Next week Review and MidtermNext week Review and Midterm
Topics: phase diagramsTopics: phase diagrams- 2 component systems:2 component systems:
- PeritecticPeritectic
- 3 component systems3 component systems
Updates/questionsUpdates/questions
Solid Solution with Eutectic:Solid Solution with Eutectic:Ab-Or (the alkali feldspars)
Figure 6-16. T-X phase diagram of the system albite-orthoclase at 0.2 GPa H2O pressure. After
Bowen and Tuttle (1950). J. Geology.
Effect of PEffect of PH OH O on Ab-Or on Ab-Or22
Figure 6-17. The Albite-K-feldspar system at various H2O pressures. (a) and (b) after
Bowen and Tuttle (1950), J. Geol, (c) after Morse (1970) J. Petrol.
Binary Peritectic SystemsBinary Peritectic Systems
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MgMg22SiOSiO44
2020 4040 6060 8080 SiOSiO22
14001400
16001600
18001800
20002000
17131713T T ooC C
MgSiOMgSiO22
1543
1470
EnstatiteEnstatiteForsteriteForsterite
Forsterite+ Enstatite
Liquid + Forsterite
1695
Enstatite + Tridymite
Enstatite + Cristobalite
Cristobalite + Liquid
Two Liquids
Liquid
Wt.% XWt.% X22
bb
ee
a
Figure 6-12. Isobaric T-X phase diagram of the system Fo-Silica at 0.1 MPa. After Bowen and Anderson (1914) and Grieg (1927). Amer. J. Sci.
ccdd
iikk mm
FoFo EnEn
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Bulk X
The Peritectic 1: X between Fo-EnThe Peritectic 1: X between Fo-En
15431543
ccdd
iikkmm
FoFo EnEn
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bulk Xbulk X
xx
yy
CrCr
The Peritectic 2: X between En-CrThe Peritectic 2: X between En-Cr
Incongruent Melting of EnstatiteIncongruent Melting of Enstatite
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ccdd
ii
FoFo EnEn
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bulk Xbulk X
CrCr
Ternary SystemsTernary Systems
C = 3: Ternary Systems:C = 3: Ternary Systems:Example 1: Ternary EutecticExample 1: Ternary Eutectic
Di - An - FoDi - An - Fo
TT
MM
AnorthiteAnorthite
ForsteriteForsterite
DiopsideDiopside
Crystallization RelationshipsCrystallization Relationships
Fo + Liq
Liquid
Di + Liq
Di + Fo
aAn
Pure Fo formsPure Fo formsJust as in binaryJust as in binary
= ? F = ?= ? F = ?
Imagine triangular plane X - Di - Fo balanced on bulk Imagine triangular plane X - Di - Fo balanced on bulk aa
Liq/total solids = a-m/Liq-a
total Di/Fo = m-Fo/Di-m
aa
DiDi
Liq xLiq x
FoFomm
Ternary lever w/ 3 phasesTernary lever w/ 3 phases
Pressure EffectsPressure Effects
