PETROLOGY Geology ONGC MCQ
Geology Model Test Paper
Q.1: Batholiths are generally associated with:
(a) Island arcs.
(b) Folded structures.
(C) Orogenic belts.
(d). Earthquake zones.
Answer. (c)
Q.2: The process of conversion of glassy material to crystallised material is known as:
(a) Crystallisation.
(b) Devitrification.
(c) Eutectic process.
(d) Assimilation.
Answer. (b)
Q.3: A rock made up of euhedral crystals, the texture is described as:
(a) Allotriomorphic.
(b)Hypidiomorphic.
(c) Panidomorphic.
(d) None of these.
Answer. (c)
Q.4: Ophitic texture is commonly shown by:
(a) Trachyte.
(b) Lamprophyres.
(C) Andesite.
(d) Dolerite.
Answer. (d)
Q.5: The Deccan trap basalt, as it is porphyric in nature, the phenocrysts are:
a) Plagioclase.
b) Plagioclase and olivine.
c) Plagioclase, olivine and clinopyroxene.
d) Olivine and clinopyroxene.
Answer. (c)
Q.6: Calc-alkaline plutonic rocks are chiefly composed of:
(a) Felspars and pyroxenes.
(b) Felspars and micas.
(c) Quartz and pyroxenes.
(d) Felspar and Quartz.
Answer. (d)
Q.7: When the groundmass is glassy in a porphyritic texture, it is called:
(a) Poikilitic texture.
(b) Orthophyric texture.
(c) Vitrophyric texture.
(d) Felsophyric texture.
Answer. (c)
Q.8: Jungel metavolcanic suite (central India) predominantly known for:
(a) Acidic basalt.
(b) Alkali basalt.
(c) Platean basalt.
(d) Tholiitic basalt
Answer. (b)
Q.9: Which one is a pure natural glass of granitic composition:
(a) Rhyolite.
(b) Pitchstone.
(c) Obsidian.
(d) None of these.
Answer. (c)
Q.10: A common decomposition in basaltic rocks involve:
(a) Oxidation of Mg.
(b) Oxidation of Fe.
(c) Hydration of Fe.
(d) Hydration of K.
Answer. (b)
Q.11: Aplite is a:
a) Fine-grained, unequigranular rock.
b) Fine-grained, equigranular, paniodiomorphic form of a plutonic rocks.
c) Fine-grained, equigranular, allotriomorphic form of a plutonic rock.
d) Volcanic rock.
Answer. (c)
Q.12: Plutonic lgneous rocks are formed under:
(a) Deep seated and moderate temp-pressure conditions.
(b) Near the earth’s surface and high temperature pressure conditions.
(c) Deep seated high temperature pressure and fast cooling conditions.
(d) Deep seated, high temperature pressure and slow cooling conditions.
Answer. (d)
Q.13: Anorthosite dominantly composed of:
(a) Oligoclase felspar.
(b) Anorthoclase felspar.
(C) Labrodorite felspar.
(d) Orthoclase felspar.
Answer. (c)
Q.14: Lamprophyres generally occur as:
(a) Batholiths.
(b) Dykes and sills.
(c) Plutons.
(d) Laccolith.
Answer. (b)
Q.15: Match the following:
I II
1. A coarse-grained, light-coloured rock. i. Rhyolite
2. A coarse-grained, dark-coloured rock. ii. Gabbro.
3. A fine-grained, light-coloured rock. iii. Granite
4. A fine-granied, dark-coloured rock. iv. Basalt.
(a) 1-iv, 2-ii, 3-iii, 4-i.
(b) 1-iii, 2-ii, 3-i, 4-iv.
(c) 1-ii, 2-i, 3-iv, 4-iii.
(d) 1-iii, 2-ii, 3-iv, 3-i.
Answer. (b)
Q.16: Name the coarse-grained (plutonic) rock consisting primarilly of sodic plagioclase and
hornblende:
(a) Syenite.
(b) Diorite.
(c) Gabbro.
(d) Granite.
Answer. (b)
Q.17: Ultrabasic basalt rich ln augite is called:
a) Oceanite.
b) Diabase.
c) Kimberlite.
d) Ankaramite.
Answer. (d)
Q.18: A rock composed of about 50% nephaline and rest consisting of other matic minerals
is generally known as:
(a) Dunite.
(b) Kimberlite
(c) Iiolite.
(d) Pulaskite.
Answer. (c)
Q.19: The first minerals to crystallise from a completely or almost anhydrous melt at high
temperature are called:
(a) Hydatogenetic minerals.
(b) Pyrogenetic minerals.
(c) Pegmatitic minerals.
(d) Orthomagmatic minerals.
Answer. (b)
Q.20 Present of water in the melt causes:
(a) Lowering of the solidus and liquidus temperatures.
(b) Rising of the solidus and liquidus temperatures.
(c) No change of the solidus and liquidus temperature.
(d) None of these.
Answer. (a)
Q.21: What is the evidence of devitrification:
(a) Corona structure.
(b) Orbicular structure.
(c) Perlitic.
(d) Percussion figure.
Answer. (c)
Q.22: Sagenitic texture is shown by:
(a) Rutile.
(b) llmemite.
(C) Ijolite.
(d) Microcline.
Answer. (a)
Q.23: Match the following:
I ll
1. Leucocratic. i. Dark coloured rock.
2. Mesocractic. ii. Light coloured rock.
3. Melanocratic. iii. Extremely dark coloured rock.
4. Hypermolanocratic. iv. Intermediate in colour.
a) 1-ii, 2-iv, 3-i, 4- iii.
b) 1-iii, 2-ii, 3-iv, 4-i.
c) 1-i, 2-ii, 3-iii, 4-iv.
d) 1-iv, 2-iii, 3-ii, 4-i.
Answer. (a)
Q.24: The larger crystals in the core of zoned pegmatites are the result of the .... of the magma:
(a) Higher viscosity.
(b) Lower viscosity.
(c) More ion concentration.
(d) None of these.
Answer. (b)
Q.25: The grain-size variation is more or less continuous from smallest to largest, the
texture is called:
(a) Seriate.
(b) Porphyritic.
(C) Poikilitic.
(d) Miarolitic.
Answer. (a)
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