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The oldest large-scale oceanic crust is in the west Pacific and north-west Atlantic — both are about up to 180-200 million years old. However, parts of the eastern Mediterranean Sea could be remnants of the much older Tethys Ocean, at about 270 and up to 340 million years old. [21] [22] [23]
These three plates were joined at a migrating, or unstable, ridge-ridge-ridge (RRR) triple junction from which the Pacific plate began to grow 190 million years ago in an area east of the Mariana Trench; this area, known as the Pacific Triangle, is the oldest part of the Pacific plate and therefore the oldest ocean floor of the Pacific.
The depth of the seafloor on the flanks of a mid-ocean ridge is determined mainly by the age of the oceanic lithosphere; older seafloor is deeper. During seafloor spreading, lithosphere and mantle cooling, contraction, and isostatic adjustment with age cause seafloor deepening. This relationship has come to be better understood since around ...
Crustal material at the western edge of the Pacific plate is some of the oldest oceanic crust on Earth (up to 170 million years old), and is, therefore, cooler and denser; hence its great height difference relative to the higher-riding (and younger) Mariana plate. The deepest area at the plate boundary is the Mariana Trench proper.
Seafloor spreading, or seafloor spread, is a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge. History of study
The oldest seafloor material found today dates to 170 Ma, whereas the oldest continental crust material found today dates to 4 Ga, showing the relative brevity of the regional Wilson cycles compared to the whole-planetary pulses seen in the arrangement of the continents.
The sunken road shows the path of an ancient people.
Mid-ocean ridge cross-section (cut-away view) A mid-ocean ridge (MOR) is a seafloor mountain system formed by plate tectonics.It typically has a depth of about 2,600 meters (8,500 ft) and rises about 2,000 meters (6,600 ft) above the deepest portion of an ocean basin.