GATE GG-1 · 2026 · GG
Question 63: Metamorphic petrology
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Question 63
GGNAT2 marksNeeds review
The Fe-Mg exchange reaction between olivine and spinel is the following:
Mg₂SiO₄ + 2FeAl₂O₄ ↔ Fe₂SiO₄ + 2MgAl₂O₄
(Fosterite) (Fe-spinel) (Fayalite) (Mg-spinel)
Assuming ideal solid solutions, the temperature of equilibrium between olivine and spinel using the following data is __________ °C (round off to nearest integer).
[Assume that ΔHᵣ⁰ and ΔSᵣ⁰ are independent of P and T, and Kd is independent of P]
| ΔHᵣ⁰ (kJ/mol) | ΔSᵣ⁰ (J/mol. K) | Kd = [(xFe^Ol xMg^Sp)/(xMg^Ol xFe^Sp)]² | R (J/mol. K) |
| −10.91 | −3.90 | 3.024 | 8.314 |
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2026GG
GATE GG-1 2026 · Paper 1
Geology and Geophysics · Original paper archive
- Section
- Section GG
- Question type
- Numerical answer (NAT)
- Marks
- 2 marks
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