Heat flow - Advanced topics in Geophysics - Geology & Geophysics Previous Year Questions

1

2008 · Geology & Geophysics · Advanced topics in Geophysics · Heat flow

Geology & Geophysics (GG) 2008

The dominant process of heat transport in the lithosphere is

A

advection

B

conduction

C

convection

D

radiation

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2

2011 · Geology & Geophysics · Advanced topics in Geophysics · Heat flow

Geology & Geophysics (GG) 2011

Which of the following rocks contributes the highest amount of radioactive heat in the earth’s crust?

A

basalt

B

gabbro

C

dunite

D

granite

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3

2012 · Geology & Geophysics · Advanced topics in Geophysics · Heat flow

Geology & Geophysics (GG) 2012

Terrestrial heat flow is the product of

A

thermal diffusivity and temperature

B

thermal conductivity and temperature

C

thermal diffusivity and temperature gradient

D

thermal conductivity and temperature gradient

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4

2014 · Geology & Geophysics · Advanced topics in Geophysics · Heat flow

Geology & Geophysics (GG) 2014

The heat flow through a unit area of the Earth’s surface is given by the product of

A

vertical thermal gradient and thermal conductivity

B

horizontal thermal gradient and thermal conductivity

C

vertical thermal gradient and thermal diffusivity

D

horizontal thermal gradient and thermal diffusivity

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5

2022 · Geology & Geophysics · Advanced topics in Geophysics · Heat flow

Geology & Geophysics (GG) 2022

The heat flow \(q\) (mW/m²) is related to the age \(t\) (My) of the ocean floor as \(t = (510/q)^2\). Assuming the temperature gradient and the thermal conductivity at a site in the Indian ocean to be 55 °C/km and 2.3 W/m °C, respectively, the age of the site is _________ My. [round off to 2 decimal places] [Use the magnitude of the calculated value of \(q\)]

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6

2024 · Geology & Geophysics · Advanced topics in Geophysics · Heat flow

Geology & Geophysics (GG) 2024 [Session 1]

Assume heat producing elements are uniformly distributed within a 16 km thick layer in the crust in a heat flow province. Given that the surface heat flow and reduced heat flow are 54 mW/m² and 22 mW/m², respectively, the radiogenic heat production in the given crustal layer in μW/m³ is __________ (in integer).

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7

2024 · Geology & Geophysics · Advanced topics in Geophysics · Heat flow

Geology & Geophysics (GG) 2024 [Session 2]

Assume heat producing elements are uniformly distributed within a 16 km thick layer in the crust in a heat flow province. Given that the surface heat flow and reduced heat flow are 54 mW/m² and 22 mW/m², respectively, the radiogenic heat production in the given crustal layer in µW/m³ is __________ (in integer).

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8

2024 · Geology & Geophysics · Advanced topics in Geophysics · Heat flow

Geology & Geophysics (GG) 2024 [Session 2]

Which one among the following factors contributes the least amount of heat to the Earth’s annual heat budget?

A

Geothermal flux from Earth’s interior

B

Reflection and re-radiation of Solar energy

C

Energy released from Earthquakes

D

Rotational deceleration by Tidal friction

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9

2025 · Geology & Geophysics · Advanced topics in Geophysics · Heat flow

Geology & Geophysics (GG) 2025 [Session 2]

In the schematic, line P shows a 1-D geothermal profile. If the heat flow at the base of the mantle increases, which line will reflect the new geothermal profile?

A

Line Q

B

Line R

C

Line S

D

Line P

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10

2025 · Geology & Geophysics · Advanced topics in Geophysics · Heat flow

Geology & Geophysics (GG) 2025 [Session 2]

Consider a steady state heat conduction equation for the Earth's crust where \( A \) is the heat source and \( k \) is the thermal conductivity. Given the boundary conditions:
i) \( T = 0 \) at the surface and
ii) \( Q \) is the heat flux at the surface,
which one of the following options would be the temperature (\( T \)) at depth \( z \)?

A

\(\frac{(Az + 2Q)z}{2k} \)

B

\(\frac{(Az + 2Q)z}{k} \)

C

\(\frac{(Az + Q)z}{2k} \)

D

\(\frac{(A + 2Q)z^2}{2k} \)

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11

2025 · Geology & Geophysics · Advanced topics in Geophysics · Heat flow

Geology & Geophysics (GG) 2025 [Session 2]

Which of the following statements is/are correct regarding the properties of the oceanic lithosphere?

A

Older lithosphere cools at a slower rate compared to younger lithosphere

B

Heat flow increases with lithospheric age

C

Heat flow in the lithosphere increases with distance from the spreading ridge

D

Thickness of the lithosphere increases with age

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12

2021 · Geology & Geophysics · Advanced topics in Geophysics · Heat flow

Geology & Geophysics (GG) 2021

The dimension of radiant emittance of a blackbody as per Stefan-Boltzmann law is:

A

M⁰L¹T⁻¹

B

M¹L⁻¹T⁻²

C

M¹L²T⁻²

D

M¹L⁰T⁻³

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13

2021 · Geology & Geophysics · Advanced topics in Geophysics · Heat flow

Geology & Geophysics (GG) 2021

In a cratonic region, radioactive heat generation decreases exponentially with depth. Assuming characteristic depth as 10 km and surface heat generation as \(3 \text{ μWm}^{-3}\) and neglecting mantle heat flow, the heat production per unit volume for a 30 km thick layer will be ______ \(\text{μWm}^{-3}\). [round off to 2 decimal places]

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14

2023 · Geology & Geophysics · Advanced topics in Geophysics · Heat flow

Geology & Geophysics (GG) 2023 [Session 1]

The heat production (Q_r) of a granitic rock due to decay of the radioactive elements U, Th and K having concentration C_U, C_Th, and C_K, respectively, is given by the expression
\[ Q_r = \alpha C_U + \beta C_{Th} + \gamma C_K \]
Which one of the following correctly represents the relation between the magnitude of coefficients α, β, γ (in μWkg^-1)?

A

α > β > γ

B

α < β > γ

C

α > β < γ

D

α < β < γ

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15

2023 · Geology & Geophysics · Advanced topics in Geophysics · Heat flow

Geology & Geophysics (GG) 2023 [Session 2]

The heat production (Q_r) of a granitic rock due to decay of the radioactive elements U, Th and K having concentration C_U, C_Th, and C_K, respectively, is given by the expression
Q_r = αC_U + βC_Th + γC_K
Which one of the following correctly represents the relation between the magnitude of coefficients α, β, γ (in μWkg^-1)?

A

α > β > γ

B

α < β > γ

C

α > β < γ

D

α < β < γ

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16

2023 · Geology & Geophysics · Advanced topics in Geophysics · Heat flow

Geology & Geophysics (GG) 2023 [Session 2]

A geothermal gradient of 32 °C/km is measured in the upper few meters of sediments covering the ocean floor. If the mean thermal conductivity of the oceanic sediments is 1.9 Wm⁻¹°C⁻¹, then the absolute value of local heat flow is __________ milli-Wm⁻². [round off to 1 decimal place]

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17

2026 · Geology & Geophysics · Advanced topics in Geophysics · Heat flow

Geology and Geophysics - Geology (GG) 2026

Consider that the upper continental crust is 10 km thick and made up of granitic rock having density of 2800 kg/m³. The surface heat flow due to radiogenic heat from the granitic rock having heat production value of 10^-9 W/kg is __________ mW/m² (answer in integer).

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18

2026 · Geology & Geophysics · Advanced topics in Geophysics · Heat flow

Geology and Geophysics - Geophysics (GG) 2026

Consider that the upper continental crust is 10 km thick and made up of granitic rock having density of 2800 kg/m³. The surface heat flow due to radiogenic heat from the granitic rock having heat production value of 10^-9 W/kg is ______________ mW/m² (answer in integer).

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