FINALS Day 2 - Petrology Flashcards
Acanthite is an ore mineral of __________.
A. Antimony
B. Silver
C. Titanium
D. Nickel
B. Silver
Chemical formula of Acanthite.
Ag2S
The following minerals are copper-bearing, EXCEPT ________.
A. Malachite
B. Digenite
C. Olivenite
D. Lepidocrocite
D. Lepidocrocite
Chemical formula of Lepidocrocite
FeO(OH)
Which of the following ore minerals is a carbonate?
A. Lepidocrocite
B. Scorodite
C. Clinoclase
D. Smithsonite
D. Smithsonite
Chemical formula of Smithsonite
ZnCO3
The following metals are found in the chemical formula of stannite, EXCEPT:
A. Sb
B. Sn
C. Cu
D. Fe
A. Sb
Chemical formula of Stannite
Cu2FeSnS4
Which mineral-element pair is correct?
A. Annabergite – As
B. Clinoclase – Sb
C. Chrysocolla – Cu
D. Stibnite - Sb
C. Chrysocolla – Cu
Chemical formula of Chrysocolla
(Cu,Al)2H2Si2O5(OH)4·nH2O
Chemical formula of Azurite
Cu3(OH)2(CO3)2
Chemical formula of Siderite
FeCO3
Chemical formula of Ilmenite
FeTiO3
Chemical formula of Digenite
Cu9S5
Chemical formula of Stibnite
Sb2S3
A microcrystalline texture formed by the devitrification of the ground-mass of acid extrusive rocks.
A. Hyalopilitic
B. Felsitic
C. Intersertal
D. Spinifex
B. Felsitic
In an ophitic texture, plagioclase is enclosed by _________.
A. Quartz
B. Biotite
C. Hornblende
D. Pyroxene
D. Pyroxene
___________ describes the layered or banded texture in explosive volcanic rocks. It is often caused by the compaction and flattening of glass shards and pumice fragments.
Eutaxitic Texture
Eutaxitic texture is commonly found in ___________.
A. Ignimbrites
B. Komatiites
C. Amygdaloidal rocks
D. Dolerite
A. Ignimbrites
Spinifex texture is commonly found in _________.
A. Dolerite
B. Gabbros
C. Granite
D. Komatiite
D. Komatiite
These are gas bubbles or vesicles that are infilled with a different secondary mineral.
Amygdules
This texture often results from resorption of quartz by the melt due to ascending and decompression or due to magma mixing.
Embayed Texture
In eutaxitic texture, pumice fragments are compacted into dark, glassy pancake shapes called _________.
Fiamme
Volcanic glass is unstable and tends to change spontaneously or devitrify from the glassy to the crystalline state. This is why ancient glasses are very rare, and most glassy rocks are of _______ age, or less than _________ years old.
Paleogene; 65 myo
It is a porphyritic texture in which phenocrysts are clustered into aggregates called crystal clots.
Glomerophyric (Glomeroporphyritic)
Glomerophyric textures form by a process known as _________, which is the accumulation of crystals by surface tension and fixing by interpenetration due to crystal growth.
Synneusis
This is a texture of volcanic rocks in which the groundmass consists of small microlites of feldspar that are sub-parallel to each other and are embedded in glass.
Hyalopilitic
The ratio of crystals to glass in this texture is greater than 3:5.
Hypocrystalline
____________ rocks were generally cooled rapidly, which inhibits growth rate and nucleation of crystals.
Holohyaline
This is the texture of an igneous rock that has crystalline components in a glassy groundmass, with a ratio of crystals to glass between 3:5 and 1:7.
Hypohyaline
This texture occurs when a crystal occupies the angular space between at least two larger crystals.
Intergranular
This texture occurs when the angular spaces between larger crystals is occupied by glass, or glass and small crystals.
Intersertal
This is a common structure of hydrated mineral in volcanic rocks such as biotite or amphiboles. It is also often described as a devolatilization process.
Opacitic Rim or Reaction Rim
A texture is ophitic when plagioclase laths are enclosed by _________ or ___________.
Pyroxene or Olivine
A texture is subophitic if plagioclase is larger and encloses which minerals?
Ferromagnesian minerals
This is a texture characterized by crystals containing small grains of other minerals.
Poikilitic
What are the two crystals in a poikilitic texture?
- Chadacrysts - smaller enclosed crystals
- Oikocrysts – larger crystals
Poikilitic texture is often found in which rocks?
Dolerites and Gabbros
In pilotassitic texture, what is the mode of arrangement of the microclites in the groundmass?
Sub-parallel
A porphyritic texture in which there is a continuous variation in crystal size is called ___________.
Seriate
This texture sometimes occurs in plagioclase wherein individual plagioclase grains show an abundance of glassy inclusions.
Sieve (Moth-eaten Texture)
This texture occurs through supercooling, where low nucleation rates and rapid crystal growth rates take place, and produces a few large skeletal or dendritic crystals.
Spinifex
This is a texture of extrusive rocks in which the groundmass contains little volcanic glass and consists predominantly of minute tabular crystals.
Trachytic
What do you call the minute tabular crystals in trachytic textures?
Sanidine Microlites
Macroscopic trachytic textures visible with the naked eye are sometimes called ________________.
Trachytoid Textures
It is a variety of inequigranular porphyritic texture in which larger crystals known as phenocrysts are embedded in a glassy groundmass.
Vitrophyric
A sandstone with less than 15% matrix content is known as:
A. Siltstone
B. Mudstone
C. Greywacke
D. Arenite
D. Arenite
The mineral coesite is expected to be stable in which of the following metamorphic
facies?
A. Greenschist
B. Blueschist
C. Eclogite
D. Granulite
C. Eclogite
A dolerite dyke metamorphosed under amphibolite facies condition is expected to have
the mineral assemblage:
A. Chlorite + Actinolite + Albite
B. Lawsonite + Glaucophane + Epidote
C. Orthopyroxene + Clinopyroxene + Plagioclase
D. Hornblende + Plagioclase
D. Hornblende + Plagioclase
TRUE or FALSE
Bouma sequence indicates turbidite deposit.
TRUE
Which of the following sedimentary structure could be used for determination top and
bottom?
A. Planer cross bedding
B. Asymmetrical ripple marks
C. Symmetrical ripple marks
D. None of the above
C. Symmetrical ripple marks
Which of the following sedimentary environments oscillation ripples are formed?
A. Alluvial
B. Beach
C. Deep sea
D. Desert
B. Beach
Which of the following is in decreasing order of particle size?
A. Sandstone, siltstone, conglomerate
B. Sandstone, conglomerate, siltstone
C. Conglomerate, sandstone, siltstone
D. Siltstone, sandstone, conglomerate
C. Conglomerate, sandstone, siltstone
Graded bedding is the result of deposition by:
A. River
B. Blowing wind
C. Moving ice
D. Turbidity currents
D. Turbidity currents
Choose the correct sequence of the deformation nd metamorphism:
A. Shale, slate, schist, phyllite, gneiss
B. Shale, slate, phyllite, schist, gneiss
C. Slate, shale, phyllite, schist, gneiss
D. Slate, shale, schist, phyllite, gneiss
B. Shale, slate, phyllite, schist, gneiss
Andesites on an average are intermediate in composition between:
A. Syenites and Gabbros
B. Basalt and Gabbros
C. Rhyolites and Trachytes
D. Anorthosite and Tjolites
B. Basalt and Gabbros
Melting of mafic crust may lead to the formation of TTGs. What does TTG mean?
tonalite-trondhjemite-granodiorite gneisses
Which of the following pair of rock and eruptive setting is correctly matched?
A. Schoshonite – Active continental margin
B. Carbonatite – Ocean island
C. Boninite – Greenstone belt
D. Trachyte – Ocean-continent collision
A. Schoshonite – Active continental margin
Which of the following Transition Element is incompatible in basalt?
A Chromium
B. Vanadium
C. Manganese
D. Titanium
D. Titanium
Dacite is a volcanic equivalent of:
A. Syenite
B. Lherzolite
C. Gabbro
D. Granodiorite
D. Granodiorite
What is the plutonic counterpart of trachyte?
Syenite
What is the volcanic counterpart of monzonite?
Latite
What is the plutonic counterpart of phonolite?
Foid Syenite
Volcanic counterpart of granite
Rhyolite
Volcanic counterpart of tonalite
Dacite
Plutonic counterpart of andesite
Monzodiorite and Monzogabbro
Rocks derived from the primary basaltic magma is characterized by:
A. Occurrence of olivine and clinopyroxene
B. Absence of olivine and feldspathoid
C. Presence of clinopyroxene and quartz
D. Presence of feldspar and quartz
A. Occurrence of olivine and clinopyroxene
Kimberlite helps what important mineral reach the surface of the Earth?
Diamond
Maximum temperature that diagenesis takes place.
200°C
These are subaqueous shrinkage cracks.
Syneresis Cracks
Occurrence of ferroan calcite cement in a carbonate rock is indicator of:
A. Sea floor diagenesis
B. Vadose diagenesis
C. Phreatic diagenesis
D. Deep-burial diagenesis
C. Phreatic diagenesis
A cross-stratified sandstone bed is a:
A. Isochronous unit
B. Time-diachronous unit
C. Suspension deposit
D. None of the above
B. Time-diachronous unit
Syn-sedimentary deformation structures are a
result of:
A. Low sedimentation
B. High sedimentation
C. Marine transgression
D. Marine regression
B. High sedimentation
Most robust radiomatric dating method that is used to date a Precambrian granite is ______.
A. C14
B. U-Pb
C. Rb-Sr
D. K-Ar
B. U-Pb
Two conditions believed to be required for the formation of igneous rocks.
Molten state and very high temperature
Where are the volcanic rocks formed?
A. Under the surface of earth
B. On the surface of earth
C. Inside the core
D. Between mantle
B. On the surface of earth
What is the grain size of volcanic rocks?
A. Very coarse
B. Coarse
C. Intermediate
D. Very fine
D. Very fine
The plutonic rocks are formed at depths below the earth’s surface ranging
A. 10 to 100 km
B. 100 to 200 km
C. 7 to 10 km
D. 1 to 5 km
C. 7 to 10 km
The rocks which exhibit mixed characteristics of volcanic and plutonic rocks are
__________.
A. Intermediate rocks
B. Mixed rocks
C. Hypabyssal rocks
D. Secondary rocks
A. Intermediate rocks
Porphyries are examples of which type of rocks?
A. Volcanic
B. Plutonic
C. Hypabyssal
D. Sedimentary rocks
C. Hypabyssal
The mineral most abundantly present in the igneous rocks is __________
A. Micas
B. Titanium
C. Iron
D. Feldspars
D. Feldspars
What is the approximate percentage of silica present in the igneous rocks?
A. 10%
B. 26%
C. 59%
D.15%
C. 59%
In a Binary System, two crystallization curves joining a point where simultaneous
crystallization of two minerals components makes place is called as:
A. Peritectic Point
B. Eutectic Point
C. Cotectic Point
D. None
B. Eutectic Point
U-Pb zircon datting is very useful to date:
A. Basaltic rocks
B. Granitic rocks
C. Ultramafic rocks
D. All the above
B. Granitic rocks
Positive Eu anomaly in a rock indicators:
A. Fractionation of plagioclase
B. Accumulation of plagioclase
C. Fractionation of oilvine
D. Accumulation of olivine + pyroxene
B. Accumulation of plagioclase
- Spinifex texture indicates:
A. Very low cooling of Magma in Plutonic Condition
B. Rapid cooling of magma in Lava flows
C. Intermediate Cooling in Dyke
D. None of these
B. Rapid cooling of magma in Lava flows
