GATE GG-1 topic:igneous-petrology PYQs & Answers — Page 2

Questions 11–20 of 37. Imported answers require independent review unless marked reviewed.

In the IUGS classification diagram for mafic and ultramafic rocks shown below, choose the correct option for the rocks labeled X and Y.

Diagram for Geology and Geophysics question 51

Your answerChoose one option.

X: Harzburgite and Y: Olivine Websterite

X: Iherzolite and Y: Olivine Websterite

X: Dunite and Y: Clinopyroxenite

X: Anorthosite and Y: Wehrlite

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Choose the explanation(s) for negative Eu anomalies in upper crustal rocks like granite and granodiorite.

Your answerSelect all correct options. You can choose more than one.

These rocks are end-products of magmatic differentiation

These rocks were formed by melting of the mantle, which was already depleted in Eu

Most of the Eu was incorporated in other minerals

The melt residues contain plagioclase which are enriched in Eu

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Choose the correct option(s) related to tectonic settings and associated rock types.

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Tholeiitic basalts and alkali basalts are both associated with mid-oceanic ridges

Andesites are commonly found in convergent plate boundaries

Tholeiitic basalts and alkali basalts can both be associated with plume-related volcanism

Volcanic rocks from subduction zones have high volatile content

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Which of the following types of deposits is/are formed by fractional crystallization of magma?

Your answerSelect all correct options. You can choose more than one.

Komatiite hosted Ni–Cu

Peridotite hosted Cr

Leucogranite hosted U

Anorthosite hosted Ti–Fe

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If ‘X’ represents the initial composition of a melt, which one of the trends indicated by arrows in the schematic diagram corresponds to the evolution of the residual melt composition during crystallization of diopside?

Diagram for Geology and Geophysics question 52

Your answerChoose one option.

III

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The diagram given below shows phase relations between components P and Q at 1 bar pressure. If ‘X’ represents the initial liquid composition, which of the following statements is/are CORRECT during equilibrium crystallization?

Diagram for Geology and Geophysics question 60

Your answerSelect all correct options. You can choose more than one.

Initial liquid composition is 60 wt.% of P and 40 wt.% of Q

The composition of the solid in equilibrium with the liquid at ‘Y’ is 10 wt.% of P and 90 wt.% of Q

The bulk composition of the final solid product is 40 wt.% of P and 60 wt.% of Q

The proportion (on the basis of wt.%) of two phases, Mₛₛ : Nₛₛ is 1 : 2 at 750 °C

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The dimension of dynamic viscosity is

Your answerChoose one option.

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Based on the given mineral proportions, which one of the following statements is CORRECT?

Rock | Mineral Proportion X | Olivine : Orthopyroxene : Clinopyroxene :: 50 : 30 : 20 Y | Plagioclase : Alkali feldspar : Quartz :: 25 : 45 : 30 Z | Biotite : Plagioclase : Alkali feldspar : Quartz :: 20 : 25 : 35 : 20

Your answerChoose one option.

Y is more felsic compared to X & Z

X is more felsic compared to Y & Z

Z is more felsic compared to X & Y

Y is the most felsic and Z is the most mafic

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Choose the CORECT statement regarding crystallization of a single feldspar of composition Or₅₀Ab₅₀ in the Albite-Orthoclase system.

Your answerChoose one option.

The mineral can form in hypersolus but not in subsolus feldspar system.

The mineral can form in subsolus but not in hypersolus feldspar system.

The mineral can crystallize in both hypersolus and subsolus feldspar system.

The mineral can crystallize neither in hypersolus nor in subsolus feldspar system.

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Which of the following options present(s) simultaneous crystallization of two minerals in the given feature(s)?

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Granophyric texture

Myrmekite

Corona of orthopyroxene around anhedral olivine

Cumulate pyroxene with interstitial plagioclase

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GATE GG-1 topic:igneous-petrology PYQs

Question 51

Question 53

Question 55

Question 37

Question 52

Question 60

Question 13

Question 19

Question 29

Question 57