Geology and Geophysics
2026 · Paper 1
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Complete GATE GG-1 2026 Paper 1 overview, original pages and practice · Timed previous-paper practice
Questions 61–63 of 65. Imported answers require review unless explicitly marked reviewed.
Question 61
Open questionGGNAT2 marksNeeds review
An oblique-slip normal fault dipping 60°E shows a net slip of 100 m. If the net slip vector has a pitch of 30°, then the heave of the fault is ________ m (answer in integer).
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A mafic magma with ‘Sr’ concentration of 400 ppm has undergone 60% fractional crystallization. If ‘Sr’ is incompatible in the mineral assemblage that crystallizes from the magma with a bulk distribution coefficient of 0.2, the concentration of ‘Sr’ in the residual liquid is __________ ppm (rounded off to nearest integer).
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You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answerQuestion 63
Open questionGGNAT2 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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