Final answer:
When subducted and accreted sediments are subjected to the pressures at a convergent margin, they undergo metamorphism, resulting in the formation of new rocks.
Step-by-step explanation:
When subducted and accreted sediments are subjected to the pressures at a convergent margin, the sediments undergo metamorphism. Metamorphism is the process by which pre-existing rocks are altered by heat and pressure, resulting in the formation of new rocks with different mineral compositions and textures. In the context of convergent margins, the high pressures and temperatures cause the sediments to undergo recrystallization, producing new metamorphic rocks.