Question

During the breakup of Pangaea, volcanic island arc systems may have formed that no longer exist. What likely happened to these arcs? 1) After subduction, the rocks were melted to form new continental crust. 2) They may have collapsed into trenches. 3) They may have been subducted along continental margins. 4) They may have been accreted onto continents after their formation. 5) They may have been broken up along divergent boundaries.

Answer 1

During the breakup of Pangaea, the volcanic island arc systems underwent processes such as being melted to form new continental crust, Plate tectonics collapsing into trenches, being subducted along continental margins, being accreted onto continents, or being broken up along divergent boundaries. The correct answer is option 3.

Step-by-step explanation:

During the breakup of Pangaea, volcanic island arc systems would have gone through several different processes. After subduction, the rocks comprising these arcs may have been melted to form new continental crust as the subducted plate is forced down into regions of high pressure and temperature which results in melting.

In general, the thick continental masses cannot be subducted, but the thinner oceanic plates are thrust down into the upper mantle at a subduction zone. Moreover, these arc systems may have collapsed into trenches or they might have been subducted.

Conversely, these arcs may have been accreted, or added, onto continents after their formation. Essentially, the arc systems become a part of the growing continent, contributing to its size and shape. Similarly, volcanic island arcs may have been broken up along divergent boundaries, The correct answer is option 3.

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