When a denser oceanic plate moves underneath a less-dense continental plate, what two types of geologic structures are produced during this plate movement?

The two types of geologic structure produced are DEEP SEA TRENCH AND CONTINENTAL ARC. Deep sea trench is a long, narrow and steep sided depression in the bottom of the sea, it is formed when one tectonic plate subducts  under another one. 
Continental arc is formed as an active continental margin where two tectonic plates and a subduction zone formed.

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