Plate Tectonics: Practice Questions

What is the primary tectonic process responsible for the destruction and recycling of oceanic crust back into the Earth's mantle?

The diagram below shows the force pulling a tectonic plate downwards into the mantle at a subduction zone.
Which driving mechanism of plate movement is represented by arrow P?

The diagram below shows the magnetic striping pattern preserved in the oceanic crust across a mid-ocean ridge. Normal magnetic polarity is represented in black and reversed magnetic polarity in white.

Which of the following correctly explains how this magnetic striping pattern provides evidence for seafloor spreading?

Which of the following is the primary driving force of global plate movements located within the hot softened mantle?

Which of the following describes the slab-pull force that drives plate motion?

Identify the specific force that occurs at subduction zones where the weight of a dense, sinking plate helps pull the rest of the tectonic plate into the mantle.

Look at the diagram showing the interaction between two plates. Identify the landform labeled \(X\) and explain why the plate on the right moves underneath the plate on the left.

A research vessel surveys an oceanic spreading ridge and records two symmetrical magnetic anomaly stripes of identical age ( \(2.5\text{ million years}\)) located on opposite sides of the ridge crest. The measured distance between these two matching stripes across the ridge is \(100\text{ km}\).

(a) Calculate the average full spreading rate of the ocean floor in \(\text{cm/year}\).
(b) With reference to rock composition and the orientation of Earth's magnetic field, explain how these symmetrical magnetic stripes are formed and preserved in the seafloor.

The theory of plate tectonics describes how large lithospheric slabs move across the Earth's surface.

(a) State the specific driving mechanism caused by heat transfer that sets up circulating currents within the asthenosphere/mantle.
(b) Name the force that operates when the cold, leading edge of a subducting oceanic slab sinks into the mantle under gravity, dragging the rest of the plate behind it.
(c) State whether the age of the oceanic crust increases or decreases as distance from a mid-ocean ridge crest increases.

The diagram below illustrates seafloor spreading and magnetic striping across a mid-ocean ridge.

(a) Identify the specific type of plate boundary found at X.
(b) Describe how the age of oceanic basalt changes from location X to location Y.
(c) Explain how alternating magnetic stripes (magnetic polarity reversals) preserved in the seafloor rock support the theory of seafloor spreading.