PHYS2403 Geophysics Simulation Lab

Experiment 7: Geothermal Heat Flow Simulator

Heat flow is the primary energy source driving geodynamics, earthquakes, and continental rift propagation. By measuring the geothermal temperature gradient in boreholes and testing rock thermal conductivity, geophysicists calculate geothermal heat flow. Explore continental crust gradients, radiogenic heat contribution, and rift heat anomalies.

Thermal Settings

Surface Heat Flow (q_s)60 mW/m²

Conductivity (K)2.5 W/m·K

Crust Heat Generation (A)1.0 μW/m³

Heat generated in crust by U, Th, and K decays.

Crust Thickness (h_c)35 km

Tectonic Presets

Standard continental crust with moderate radiogenic heating.

Add Borehole thermometer noise

T(z) Column

Visual temperature column gradient to 100km

Moho: 35 km

200°C (9 km)

400°C (19 km)

600°C (34 km)

800°C (54 km)

Geothermal Profile CurvedT/dz ≈ 23.0 °C/km

T_moho: 555 °C (at 30km)T_mantle: 1260 °C (at 100km)

Fourier's Law

Thermal conduction is governed by Fourier's Law. Heat flow $q$ is the product of thermal conductivity $K$ and temperature gradient $dT/dz$ .

q = -K \frac{dT}{dz}

Radiogenic Heating in Crust

The presence of radioactive elements ( $^{238}\text{U}$ , $^{232}\text{Th}$ , $^{40}\text{K}$ ) in continental rocks generates internal heat, causing the temperature profile to curve.

T(z) = T_s + \left(\frac{q_s}{K}\right)z - \left(\frac{A}{2K}\right)z^2

Deep Heat Flow

The mantle contribution to surface heat flow. In cratons, crustal radioactive heat can contribute up to 50% of surface heat flow!

q_{\text{deep}} = q_s - A \cdot h_c