Science Olympiad Dynamic Planet Practice Test

What is the characteristic temperature range of the upper boundary of the mantle?

1. 200 to 500 °C

2. 500 to 900 °C

3. 1,000 to 2,000 °C

4. 2,500 to 3,000 °C

The correct answer is: 500 to 900 °C

The characteristic temperature range of the upper boundary of the mantle is between 500 to 900 °C. This range reflects the thermal conditions found at the lithosphere-asthenosphere boundary, which marks a transition from the cooler, rigid lithosphere into the more ductile asthenosphere below. At temperatures below this range, the mantle rock remains relatively solid and behaves in a brittle manner, while temperatures that reach up to about 900 °C allow for some partial melting, which leads to a more ductile behavior important for mantle convection and tectonic processes. This temperature range is significant for understanding geological activity, as it plays a crucial role in the dynamics of plate tectonics and the formation of various geological features. Higher temperature ranges, such as those above 1,000 °C, correspond to deeper levels within the mantle or even entering the transition zone, while the ranges exceeding 2,500 °C would be found in the lower mantle closer to the core-mantle boundary, where pressures and temperatures far exceed those of the upper boundary of the mantle. This context clarifies why the selected range is recognized as characteristic for the upper boundary of the mantle.