If the east pacific rise is the source of new rock which trench would contain the oldest rock?

The oldest rock would be found in the Mariana Trench, which is located in the western Pacific Ocean. As the East Pacific Rise creates new oceanic crust through seafloor spreading, the older crust moves away from the ridge and eventually gets subducted at trenches like the Mariana Trench. This process results in the trench containing some of the oldest oceanic rock, as it represents the remnants of the Earth's crust that have been pushed into the subduction zone.