Geology and Geophysics
GATE GG-1 topic:igneous-petrology PYQs
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How to practice topic:igneous-petrology
Attempt a question, record the concept and assumptions, then check the available answer. Rework mistakes after revising the relevant concepts. Topic tags can overlap; review the question context.
Questions 1–10 of 37. Imported answers require independent review unless marked reviewed.
Question 13
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Which one of the following is NOT a volcanic igneous rock?
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The given table shows modal volume percentage of quartz, alkali feldspar and plagioclase in coarse-grained rocks, X and Y. Which of the following rock names of X and Y are CORRECT according to the IUGS classification?
Mineral | X (volume %) | Y (volume %) |
|---|---|---|
Quartz | 15 | 25 |
Plagioclase | 20 | 60 |
Alkali feldspar | 65 | 15 |
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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 47
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The ternary diagram given below shows phase relations for the Anorthite-Diopside-Forsterite system at 1 bar pressure. Broken lines represent isotherms with temperature in °C. If ‘P’ is the initial melt composition, which one of the following is the CORRECT sequence of crystallization assuming equilibrium between crystal and melt?
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Accumulation of which one of the following minerals can explain positive Eu and positive Sr anomalies in the primitive mantle-normalized multielement pattern of an igneous rock?
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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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The continuous series of Bowen’s reaction series is represented by
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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 29
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The combinations listed below represent major minerals observed in four igneous rocks:
(i) Olivine and Anorthite, (ii) K-feldspar and Quartz, (iii) Mg-Ca-pyroxene and Ca-Na-plagioclase, (iv) Amphibole and Na-Ca-plagioclase
Arrange these mineral combinations based on decreasing temperature of magma crystallization.
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Which of the following rock and texture combinations is/are CORRECT?
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Compared to Fe, Mg, and Ca, the content of K is extremely low in igneous clinopyroxene. Which of the following CANNOT explain its low abundance?
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In a hypothetical scenario, the element Y has 4 stable isotopes
Y,
Y,
Y and
Y. The isotope
Y is radiogenic and is formed by β
decay of the isotope
X of the element X with a half-life of 3.51 billion years. An igneous rock, which has behaved as a closed system, has three different minerals P, Q, and R, which crystallized from the same magma 2 billion years ago, with initial X/Y ratios of 1.75, 2.05, and 0.75, respectively. Which one of the following statements is true for the ratio
Y/
Y in this igneous rock in the present day?Your answerChoose one option.
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