JAM 2026 Question Paper Geology (GG)

JAM 2026 Confidential Geology (GG)

Section A: Q.1 – Q.10 Carry ONE mark each.

Q.1 Which one of the following primary structures can be used for paleocurrent
measurement?

(A) Oscillation ripple

(B) Hummocky cro
ccross-strata
ross
ro ss-strata
ss

(C) Flute cast

(D) Load and flame
flam
lame
me structures
sstr
truc
tr uctu
uc ture
tu res
re

GG Page 3 of 44

JAM 2026 Confidential Geology (GG)

Q.2 Which one of the following minerals does NOT show changes in optical
properties upon exposure to UV light?

(A) Apatite

(B) Calcite

(C) Fluorite

(D) Scheelite

Q.3 Choose the m
mat
ater
ateria
er iall on which
ia
material whi
w ch 14C da
hich
hi dati
ting
ting technique
dating techn
hniq
ique
ue ccan
an be co
corr
orrectly
rrec applied.
rr
correctly

(A) Charred food grains from the Indus Valley civilization

(B) Organic matter in carbonaceous chondrites

(C) Diamonds from the Earth’s interior

(D) Graphite from Proterozoic sedimentary basins

GG Page 4 of 44

JAM 2026 Confidential Geology (GG)

Q.4 Which one of the following rock combinations is characteristic of volcanic arcs?

(A) Basalt-andesite-dacite

(B) Basalt-trachyte-rhyolite

(C) Andesite-syeni
Andesite-syenite-dacite
yenite
te-d
te -dac
-d acit
ac itee
it

(D) Trachybasalt-basaltic
Trachybasalt-
lt-b
-bas
-basaltic andesite-andesit
as andesite-andesite
itee

Q.5 The rake (pitch)
pitch)
h) ooff sl
slic
slickenlines
icke
ic kenl
kenlin
nl ines
in es eexp
exposed
xpos
xp osed
os ed on
n a mo
mode
moderately
dera
de rate
rately dipping
te dip
ippi
ip ping
ping fault plane
is the angle between
be
bet
etwe
etween
ween

(A) the magnetic north and strike of the fault plane measured on a horizontal surface

(B) the strike of the fault plane and the slickenlines measured on the fault plane

(C) the strike of the fault plane and the slickenlines measured on a vertical plane

(D) the trend and the plunge directions of slickenlines measured on the fault plane

GG Page 5 of 44

JAM 2026 Confidential Geology (GG)

Q.6 Match the geographic locations listed in Column 1 to the geodynamic features
listed in Column 2.

Column 1 Column 2

P. Iceland i. Triple junction

Q. Afar ii. Plume-ridge interaction

R. Hawaii iii. Subduction zone

S. Aleutian Islands iv. Plume

(A) P-i; Q-ii; R-iv;
R-iv
-iv;
v; S-iii
S-i
S -iii
-iii

(B) P-ii; Q-i; R-iv
R-iv;
-iv;
v; S
S-iii
ii

(C) P-ii; Q-i; R-ii
R-iii;
-iii
ii; S-
S-iv
iv

(D) P-ii; Q-iv; R-i; S-iii

GG Page 6 of 44

JAM 2026 Confidential Geology (GG)

Q.7 Which one of the following observations is consistent with the solid nature of the
Earth’s mantle?

(A) S waves propagate through the mantle

(B) S waves do not propagate through the mantle

(C) P waves prop
propagate
opag
agat
agate through
at throug
ughh the
ug th mantle
mant
ma ntle
ntle

(D) P waves aree refracted
re
refr
frac
fracted in the mantle
ac

Q.8 Which one of tthe
he fol
ollo
ollowi
lowing
wing is
following is a nektic
nekt
nektic
ktic bivalve?
bivalve
b ve??

(A) Gryphaea

(B) Trigonia

(C) Mytilus

(D) Solen

GG Page 7 of 44

JAM 2026 Confidential Geology (GG)

Q.9 Which one of the following is characteristic of a point bar succession?

(A) Thick homogenous sandstone

(B) Upward gradation from sandstone to shale

(C) Upward grada
gradation
dation
on from
ffro
rom
rom shale
shal
shalee to sandstone
al ssan
ands
an dsto
dstone
to ne

(D) Thick laminated
laminat
nate
tedd shale
te

Q.10 Tsunamis are
re ffre
frequently
requ
re quen
quentl
en tlyy ca
tl caus
caused
used
used b
byy ea
eart
earthquakes
rthqua
rt uake
kess at

(A) slow-spreading
ding ridges

(B) fast-spreading ridges

(C) subduction zones

(D) transform faults

GG Page 8 of 44

JAM 2026 Confidential Geology (GG)

Section A: Q.11 – Q.30 Carry TWO marks each.

Q.11 In the 87Rb -87Sr isotopic systematics applied to terrestrial rocks, the slope of

the isochron ! "# $ 1% can be approximated as lt, where l is the decay constant

and t is time. Choose the correct option that justifies this approximation.

87
(A) t 87Sr following a linear law
Rb decayss to

(B) The Rb/Sr rati
rat
ratio
tioo is susceptible
ti le to
to alteration
alte
altera
terati
ration
tion in
in terrestrial
terr
te rrestrial rocks
rock
ckss
ck

(C) l is very sma
small
mall for 87Rb
ll for

(D) Age of the Ear
Earth
Ea
arth
ar half-life
th > hhal
alf-life
al off 87Rb
fe o

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JAM 2026 Confidential Geology (GG)

Q.12 A halide with octahedral cleavage can scratch calcite and can be scratched by
quartz. Identify the halide.

(A) Sylvite

(B) Fluorite

(C) Apatite

(D) Halite

Q.13 Choose the corre
cor
orre
or rect statement
re
correct ssta
tate
ta teme
tement
me nt about
aabo
bout
bo ut Moho.
Moh
Moho.
oh

(A) Seismic and petrologic Moho coincide

(B) Seismic Moho lies at shallower depths relative to the petrologic Moho

(C) Petrologic Moho lies at shallower depths relative to the seismic Moho

(D) Petrologic Moho lies above the layered gabbro in ophiolites

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JAM 2026 Confidential Geology (GG)

Q.14 Stratigraphic sections S1 and S2, separated by tens of kilometers, are shown in
the schematic. The line segments in this schematic represent biostratigraphic
correlation between S1 and S2. Which one of the segments (P, Q, R, S) of this
correlation line represents an unconformity?

(A) P

(B) Q

(C) R

(D) S

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JAM 2026 Confidential Geology (GG)

Q.15 The S wave velocity &' is given by &' = ()+*, where ) is shear modulus and *

is density of the medium. &' is lower in mantle plumes than in the ambient mantle
because of

(A) lower temperature of mantle plumes

(B) lower density
ity of m
mantl
mantle
tle pl
plumes

(C) higher densit
density
sity
ty ooff mantle plume
plumes
mess
me

(D) lower shear mo
modu
modulus
m du
dulus of man
mantle
antl
an tlee pl
tl plumes

Q.16
Which one of tthe
he ffol
following
ollo
ollow
lowing
ng environments
eenv
nvir
nviron
ironme
on ment
me ntss best
nt best characterizes
ccha
hara
haract
ra cter
cteriz
er izes
izes the
the natural
n habitat
of boring bivalves,
biva
valv
valves
lv green
es, gr
es gree algae,
eenn al
ee alga
gae,
ga e, aand herbivorous
nd h
her
erbi
erbivo
bivoro
vo rous
ro snails?
us ssna
nail
na ils?
il s?

(A) Deep marine

(B) Rocky intertidal coast

(C) Outer shelf

(D) Estuary

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JAM 2026 Confidential Geology (GG)

Q.17 Match the minerals in Column 1 to their characteristic optical properties in
Column 2.

Column 1 Column 2

P. Zircon i. Pink to green pleochroism
Q. Orthopyroxene ii. Very high positive relief
R. Muscovite iii. Cyclic
Cyc
yclic twinning
S. Cordierite
Cord
Cordierite
rd iv. Third order b
bir
birefringence
irefringence
iref
ir efri
ef

(A) P-ii; Q-i; R-iii;
R-ii
-iii
ii; S-iv
S-iv

(B) P-i; Q-ii; R-iv
R-iv;
-iv;
v; S
S-iii
ii

(C) P-ii; Q-i; R-iv
R-iv;
-iv;
v; S
S-i
S-iii
-iii
-iii

(D) P-ii; Q-iv; R-i; S-iii

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JAM 2026 Confidential Geology (GG)

Q.18 Match the magma series in Column 1 to the geological settings in Column 2.

Column 1 Column 2

P. Alkaline Series i. Divergent oceanic margin

Q. Shoshonite Series ii. Oceanic intraplate

R. Calc-alkaline Series iii. Convergent plate margin

iv. Convergent
Converge
gent plate
p margin
m
S. Tholeiitic
Thol
Th olei
oleiit
ei itic
itic Series
Ser
Serie
eriess
ie
close to back arc

(A) P-i; Q-iv; R-iii;
R-i
-iii
ii;; S-ii
ii S-ii

(B) P-ii; Q-iv; R-ii
R-i
R-iii;
iii;
ii i; S-i
-i

(C) P-ii; Q-i; R-ii
R-iii;
-iii
ii; S-
S-iv
iv

(D) P-iv; R-ii; Q-i; S-iii

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JAM 2026 Confidential Geology (GG)

Q.19 Match the plant fossils in Column 1 to the corresponding geological ages in
Column 2.

Column 1 Column 2

P. Glossopteris i. Triassic

Q. Ptilophyllum ii. Devonian

R. Dicrodium-Thinnfeldic iii. Triassic to Lower
Cretaceous

S. Psilophyton
Ps iv. Permiann

(A) P-iv; Q-iii; R-i
R-i;
-i;; S-ii
-i S-ii

(B) P-iii; Q-iv; R-i
R-i;
-i;; S-
-i S-ii
ii

(C) P-iv; Q-iii; R-ii;
R-i S-i

(D) P-iv; Q-i; R-iii; S-ii

GG Page 15 of 44

JAM 2026 Confidential Geology (GG)

Q.20 Which one of the following reasons best explains the occurrence of large number
of earthquakes at the active plate boundaries compared to the plate interiors?

(A) Strain energy accumulation is higher at the plate boundaries

(B) Stiffness is higher at the plate boundaries

(C) Heat flow is llower
low
ower
ow er at the plate
plat
platee bo
at boun
boundaries
unda
un dari
da ries
ries

(D) Crust is thinner
nner
er aat the plate boundaries

Q.21
If P, Q, R, andd S refe
refer
ferr to R
fe Rai
Rainfall
ainf
ainfal
nf alll induced
al indu
duce
ced landslide,
land
ndsl
slid
ide,
e, Bolide
Bolid
B ide impact,
id impa
impa Milankovitch
Sup
uper
up erco
ercont
contin
ntinen
inent cycle,
en
cycle, and Supercontinent cycl
cle,
cle, rres
espe
espect
ctivel
ely,
y, then
respectively, t whic
wh ich
ic
which h one
one of the following
correctly repr
represents
pres
esen
es ents
ents the
the decreasing
ddec
ecre
ec reas
re asin
as g order
ing
in orde
or derr of their
de tthe
heir
he ir duration?
dur
d urat
ur atio
ation?
ion?

(A) S, R, P, Q

(B) Q, P, R, S

(C) S, Q, P, R

(D) S, P, Q, R

GG Page 16 of 44

JAM 2026 Confidential Geology (GG)

Q.22
The schematic shows a geological cross-section of a faulted region of
sedimentary rocks (beds P to U). Assuming continuous sedimentation, select
the beds that record the earliest activation and the latest reactivation of the fault.

(A) Q, T

(B) P, T

(C) Q, R

(D) Q, U

GG Page 17 of 44

JAM 2026 Confidential Geology (GG)

Q.23 In a single layer of an anticline, the dip isogons converge towards the inner
surface (core). Which one of the following statements is correct for the
curvature of the inner surface of this folded layer?

(A) Curvature of tthe
he iinn
nner
nn er ssur
inner urfa
ur ce > Curvature
face
fa
surface Cur
Curva
ur vatu
vature
ture of
of the
the outer
oute
outerr surface
te surf
surfac
rface
ac

(B) Curvature of tthe
he iinner surface < Cur
urva
vature of
Curvature of the outer surface
surfac
acee
ac

(C) Curvature of tthe
he iinner surfa
face = Curvature of thee outer
face
surface ou r surface
surfac
acee
ac

(D) Curvature of tthe
he iinn
inner
nner
nn er ssur ce = Curvature
surface
urfa
ur face
fa Cur
Curva
ur vature of
va of the
the median
medi
median surface
di sur
urface
urfa
ur face
fa

GG Page 18 of 44

JAM 2026 Confidential Geology (GG)

Q.24
In an arid environment, winds of similar intensity blow in nearly opposite
directions in alternate seasons. Which dune type is most likely to form in
such an environment?

(A) Barkhan

(B) Transverse dun
dune
unes
unes
dunes

(C) Seif

(D) Lunate

Q.25 Which one of tthe
he ffol
following
ollo
ollow
lowing
ng features
feature
ress is used
re use
used
sed to define
defin
inee the
in the K-Pg
K-Pg boundary
bou
globally?

(A) Absence of dinosaur fossils

(B) Presence of iridium anomaly in sediments

(C) Presence of high mercury content in sediments

(D) End of Deccan volcanism

GG Page 19 of 44

JAM 2026 Confidential Geology (GG)

Q.26 The figure shows chemogenic mineral projections for Facies P and Facies Q.
Which one of the following reactions best represents change from Facies P to
Facies Q?

(A) Wo + An = Sil
S l + Qt
Qtzz

(B) An + Sil = Wo

(C) Wo + Crn = Grs

(D) Grs + Qtz = Wo + An

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JAM 2026 Confidential Geology (GG)

Q.27 The figure depicts stability fields of minerals P and Q. Which one of the following
statements is INCORRECT?

(A) P and Q cann co
coex
coexist
exis
existt at ddif
is different
iffe
if fere
fe rent
rent ttem
temperatures
empe
em pera
peratures on
only
ly iiff pr
pressure
pressures
ress ar
re are different

(B) P and Q cann co
coex
coexist
exis
existt wi
is with liq
liquid
iqui
iquidd only aatt one pr
ui pres
pressure
essu
es sure and
su nd ttem
temperature
empe
em pera
pe

(C) Q has a higher
gher mel
elti
el ting ttemperatu
ti
melting ture aatt hi
tu
temperature high
gher pressures ttha
gh
higher han at llow
ha
than lower pressures

(D) A reaction forming Q from P at constant pressure will require an input of heat

GG Page 21 of 44

JAM 2026 Confidential Geology (GG)

Q.28 Match the metal associations in Column 1 to corresponding hosts in Column 2.

Column 1 Column 2

P. Cu, Co, Zn i. Tectonized dunite and harzburgite
Q. Mn, Co, Ni ii. MORB
R. Cr iii. I-Type granite in volcanic arc
S. Cu, Mo, Pb iv. Pelagic sediment

(A) P-ii; Q-iv; R-i;
R-ii; S-iii
S-i
S-iii
-i

(B) P-iv; Q-ii; R-i;
R-ii; S
S-i
S-iii
-iii
-iii

(C) P-ii; Q-iv; R-ii
R-i
R-iii;
iii;
ii i; S
S-i
-i

(D) P-ii; Q-i; R-iv;
-i S-iii

GG Page 22 of 44

JAM 2026 Confidential Geology (GG)

Q.29
Which one of the following mineral associations is diagnostic of the highly-
oxidized zone of a weathered primary base metal vein?

(A) Smithsonite, Malachite, Anglesite

(B) Calcite, Fluorite,
orite, Pyrite

(C) Limonite, Real
Rea
Realgar,
alga
algar, Chalcoc
ga Chalcocite
ocit
oc itee
it

(D) Goethite, Orpi
Orpiment,
Orp
pime
piment, Boehmite
me

GG Page 23 of 44

JAM 2026 Confidential Geology (GG)

Q.30 Match the features in Column 1 to the most appropriate description in Column 2.

Column 1 Column 2

P. Ash layer i. Part of a turbidite sequence

Q. Graded bedding ii. Subaerial episode in the sedimentary record

R. Hiatus iii. Dating of sedimentary rocks

S. Soil profile iv. Missing faunal zone

(A) P-iii; Q-i; R-iv;
R-iv S-ii

(B) P-i; Q-iii; R-iv; S-ii

(C) P-iii; Q-i; R-ii; S-iv

(D) P-iii; Q-iv; R-i; S-ii

GG Page 24 of 44

JAM 2026 Confidential Geology (GG)

Section B: Q.31 – Q.40 Carry TWO marks each.

Q.31 Choose the correct statement(s) related to different aspects of volcanism.

(A) Andesites are the most common rock type associated with stratovolcanoes

(B) Explosiveness
ess of volcanism depends on viscosity and fluid content
conten of the magma
co

(C) Shield volcanoes
cano
noes
noes represent one
ne of
of the
the la
larg
largest
rges
rgestt ma
es magmatic ventt landforms
land
la nd

(D) Pillow lavas
as reflect
re
ref
efle
eflect sub-aerial
le sub
ub-aer
eriall volcanic
er vo eruptions
erupt
ptio
ions
ns

GG Page 25 of 44

JAM 2026 Confidential Geology (GG)

Q.32 Which of the following processes is/are responsible for the alternate bands of
magnetic polarity observed in seafloor basalts?

(A) Convection in the mantle

(B) Convection in the outer core

(C) Convection inn the
the inner core
core

(D) Seismicity at mid-oceanic
mid-
mid-oceanic ridges
d-

Q.33 The Earth’s gr
grav
gravitational
avitatio
av iona
io nal acceleration
na acce
accele
ce lera
le rati
ra tion
ti on iis higher
high
gher
er at
at th
the po
pole
poles
les compared
le comp
comp to that at the
equator due to

(A) higher density rocks at the poles

(B) shorter polar radius

(C) lower centrifugal acceleration at the poles

(D) higher topography at the poles

GG Page 26 of 44

JAM 2026 Confidential Geology (GG)

Q.34 During glacier retreat following the last Ice Age, Scandinavia experienced
isostatic rebound. Which of the following resulted due to this rebound?

(A) Fall in water level in glacial lakes

(B) Rise in water level in glacial lakes

(C) Raised beache
beaches
ches
es

(D) Deep earthquakes
earthqu
quak
akes
ak es

Q.35 accum
cumu
mula
mu lation
la on ooff hy
Natural accumulation hydr
droc
dr ocar
oc arbo
arbons
bo
hydrocarbons ns are expected
exp
xpec
ected
d to occur
o

(A) in an anticline

(B) in stratigraphic traps

(C) along synclinal axial troughs

(D) in ancient delta-mouth bars

GG Page 27 of 44

JAM 2026 Confidential Geology (GG)

Q.36 Which of the following factors affect(s) the intrinsic spatial resolution of remote
sensing imagery?

(A) Sensor pixel size

(B) Altitude of the satellite

(C) Wavelength
th off th
the captured
ed eele
electromagnetic
lect
lectro
ct roma
romagn
ma gnet
gn etic
etic rrad
radiation
adia
adiati
ia tion
tion

(D) Satellite communication
comm
mmun
mm unication bandwidth
un

Q.37 Two sandstone
onee re
rese
reservoir
serv
se rvoi
rvoirr rocks
oi rock
ro ckss R1 and
ck and R2 have
have 2
25%
5% p
por
porosity
orosity
or y ea
each but the
ty of
permeability of R1 is
is hi
higher than
ttha
han
ha n that of
o R2. Which
Whic
Wh ich of the
ic the following
ffol
ollo
ollowi can explain
lo
this difference
ncee in permeab
permeability?
abil
ab ilit
il ity?
ity?

(A) Clay content in R1 is more than that in R2

(B) Microfracture density in R1 is higher than that in R2

(C) Sorting in R1 is better than that in R2

(D) R1 has more angular grains than R2

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JAM 2026 Confidential Geology (GG)

Q.38 In the following illustration, PQRS is an exposed axial planar cleavage,
striking north-south and dipping 40° east. B1 and B2 are the traces of two
folded bedding planes on this axial planar cleavage. The fold can be classified as

(A) horizontal fold

(B) inclined fold

(C) plunging fold

(D) upright fold

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JAM 2026 Confidential Geology (GG)

Q.39 Intrusion of a 10-meter thick dolerite dyke into a boron-rich quartz-garnet-biotite-
muscovite-chlorite schist developed a visible symmetric baked zone. Which of the
following minerals can develop in this baked zone, 2 meters away from the margin
of the dyke?

(A) Orthopyroxene

(B) Clinopyroxe
enee
Clinopyroxene

(C) Amphibole

(D) Tourmaline

Q.40 Which of the
he ffol
following
ollowi
ol wing
ng ore
ore ttyp
types
ypes
yp es form(s)
ffor
orm(
orm(s)
m(s) b
byy ma
magm
magmatic
gmat
gmatic
atic differentiation?
differe
d rent
re ntia
nt

(A) Gold in quartz vein

(B) Titaniferous magnetite in anorthosite

(C) Columbite-Tantalite in pegmatite

(D) Chromite-Pentlandite in pyroxenite

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JAM 2026 Confidential Geology (GG)

Section C: Q.41 – Q.50 Carry ONE mark each.

Q.41 One mole of a parent nuclide is undergoing radioactive decay. The fraction of
atoms of this nuclide that has decayed after three half-lives is ____________.
(
(Round places)
off to three decimal places)

Q.42 The lithostatic
taticc pr
pressure at the base of a 35 km thick continen
continental
enta
entall cr
ta crust of average
density of 2.8 g/cc
.8 gg/c __________ × 108 Pa.
_______________
/cc is ______
/c ____
__ __ (Round
Pa. (Ro
Roun
Round of
un offf to one
o decimal place)

(Consider the va
valu
luee of aacc
lu
value ccel
cc eler
elerat
eratio
at ion
io
acceleration n du
duee to gravity
ty as
as 9.
9.8 m/s2)
8 m/s

Q.43 A hypothetical mineral has the formula X7Si8O22(OH)2, where X is a cation.

The valence state of X is _________.
__. (In
( integer)
integer)

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JAM 2026 Confidential Geology (GG)

Q.44 The surface subsidence at a horizontal distance , from the centerline of a
34 5
cylindrical tunnel is given by -./0 × exp 2 :;<where -./0 is the
6789 5
maximum subsidence above the tunnel and > = ?@ m is the depth of the tunnel
centerline. The ratio of surface subsidence at , = 1@ m to that at , = A@ m
is __________.
__. (Round
( place)
off to one decimal place)

Q.45 An aquifer with a hydraulic conductivity of 60 m/day experiences a head loss
of 20 m over a length of 1000 m. The flow of water per unit area, in millimeter
per minute, is _____________ . (Round
( places)
off to two decimal places)

GG Page 32 of 44

JAM 2026 Confidential Geology (GG)

Q.46 Sphalerite shows limited isomorphism. Consider a colourless sphalerite having
33% S and 67% Zn. Then, in a black-coloured sphalerite, with a 15% Fe
substitution, the ratio of atomic proportions of Zn to that of Fe is ____________
(
(Round off to one decimal place)
place)

(Given: atomic weight of Zn = 65.37, Fe = 55.85, and S = 32.06)

Q.47 The true dip
ip ooff a normal limbb as
asso
associated
soci
sociat
ciated
ated w
wit
with
ith
it h as ding is 20° and the
asymmetric folding
fol
oldi
oldi

angle that this
his li
limb 35°. Th
mb makes with the axial planar cleavage is 35 The true dip of
the axial plana
anar
ar ccleavag
planar age, iin de
cleavage, degr
gree, is _____
gr
degree, ____
______
____
___
__
______________ _ . (In
In iint
nteg
nt
integer)

Q.48 A metallic mineral weighs 44 g and displaces 11 mL of water when fully
immersed. The density of the mineral is ____________ g/cc. (In integer)

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JAM 2026 Confidential Geology (GG)

Q.49 A clinopyroxene crystal in a basalt, measured to have a composition of
Mg1.2Fe0.4Ca0.4Si2O6, will have Mg-number (Mg#) of ____________ %.
(In integer)

Q.50 The figure shows
ws a ccor
coral
oral
oral rree
reef
eeff de
ee depo
deposit
posi
positt at tthe
si he ccon
continental
onti
ontine
ti nent
ne ntal
ntal m
mar
margin
argi
argin si
gi since 120 Ma.
Assuming that
hatt th
there was no ssea
sea-level
ea-l
ea -lev
-level ccha
ev change,
hang
ha nge,
nge, tthe
he aave
average
verage sub
ve subsidence
ubsi
ub side
si rate of
continental
this continent
ntal margin is ______________ mm/year.
al m mm/y undd off
/year. ((Roun
/y (Round
ound
un of to three decimal
places)

GG Page 34 of 44

JAM 2026 Confidential Geology (GG)

Section C: Q.51 – Q.60 Carry TWO marks each.

Q.51 eNd is the deviation of 143Nd/144Nd of a sample relative to CHUR in
parts per 104. For a pyroxenite with measured 143Nd/144Nd = 0.512838 and
147
Sm/144Nd = 0.21, the initial eNd at 1 Ga is ______________ . (Round off only

the final answer to one decimal place)

C UR, 143
CHUR
UR
(Given: for CHUR, 143
Nd//144
Nd 144
Nd = 0.512638
0.5
0 .512
.51263
12 638
63 d 147
8 and 147
Sm/144
144
Nd = 0.1967. The decay

or 147
constant for 147
54 ×10−12 yr
Sm is 6.54 yr−1)

Q.52 A sandstonee sa
samp
sample
mple w
mp wit
with
ith 100%
it 100% q
qua
quartz
uart
ua rtzz has a porosity
rt poro
porosi
sity of
of 30%.
30%. The
T sample is dry
and the density
nsityy of qqua
quartz
uart
ua rtz is 2.65
rt 22.6
.65
.6 5 g/cc. The
Th bulk
lk density
den
density
en ty of
of the
the sandstone
sand
sa sample
is _________ g/cc
/ccc ((Round
__ gg/c
/c Roun
Round of
un offf to one decimal
ne d
dec
ecim
imal
im al p
place)

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JAM 2026 Confidential Geology (GG)

Q.53
A mountain of height 5 km is in static equilibrium with a crustal block of zero
elevation. If the density of the crust and the mantle are 2700 and 3300 kg/m3,
respectively, the thickness of the mountain root (h) is ________ km (Round off
to one decimal place)

Q.54 In a mineralized
alized
ed sta
staurolite-garnet-biotite
taur
ta urol
urolite-ga
ol garn
ga rnet-bioti
rn tite
tite schis
schist,
ist,
t, the
the estim
estimated
imat
im ated
at ed m
met
metasomatic sulfide
mineralization
tion
on iss 4%
4%, wi
with ore min
mineral
iner
in eral
eral ppro
proportions
ropo
roportions aass 30
po 30%% ch
chal
chalcopyrite,
alco
al 20%
pyrite and the
he rres
rest
estt be
es bein
being
ingg ma
in magn
magnetite.
gnet
gnetit
et ite.
ite. T
The
he m
max
maximum
axim
ax imum
im um ggra
grade
rade
rade ooff Cu w
will be
__________ g/ton
/t (Round
(Ro d off to the
he nearest integer)
i )

(Given: 1 ton = 1000 kg; atomic weight of Cu = 63.55, Fe = 55.85, O = 16.00
and S = 32.06)

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JAM 2026 Confidential Geology (GG)

Q.55
Four vertical boreholes are drilled on a flat topography at 50 m intervals along
the east-west direction. The boreholes intersect a coal seam at depths of 100 m,
130 m, 160 m and 190 m. The true dip of the coal seam, in degree, is _______.
(Round
( off to two decimal places)
places)

Q.56 Consider a perfect Geocentric Axial Dipole model for the geomag
geomagnetic field. At a
latitude of 30°N, the inclination of a freely suspended magnetic
magne
netic needle,
ne ne in degree,
is __________
____ . ((Round
Round off
off to tthe nearest
he n
nea
eare
rest
re integer)
st iint
nteg
nteger
eger))
er

GG Page 37 of 44

JAM 2026 Confidential Geology (GG)

Q.57
The figure shows the 14C activity with depth in a sediment core from a lake,

where the sedimentation rate was uniform. The maximum 14C activity, marking
the signature of bomb carbon, was measured at a depth of 45 cm. The rate of
sedimentation is __________ mm/year
year (In
( integer)
integer)
(Given: the core top reflects the year of coring and bomb carbon reached its
global maximum in 1965)

GG Page 38 of 44

JAM 2026 Confidential Geology (GG)

Q.58 Based on the figure, the anorthite content of first formed plagioclase crystals from
a liquid composition having 50 mole % anorthite is _________ mole % (In integer)

GG Page 39 of 44

JAM 2026 Confidential Geology (GG)

Q.59 The figure shows variation in optical properties of plagioclase feldspars
with composition. A feldspar from a lunar anorthosite, with anorthite mole%
of 85, will have a birefringence of ____________ (Round off to three decimal
places)

Q.60
In the isometric system, the difference in the number of symmetry planes in class
F
BC DE (Hextetrahedral) class and . DC (Diploidal) is ____________
_____
__ ((In integer
integer))

GG Page 40 of 44