Geology of the Pacific Ocean Geology of the Pacific Ocean The Pacific Ocean evolved in the Mesozoic from the Panthalassic Ocean, which had formed when Rodinia rifted apart around 750 Ma. The first ocean floor which is part of the current Pacific Plate began 160 Ma to the west of the central Pacific and subsequently developed into the largest oceanic plate on Earth. The tectonic plates continue to move today. The slowest spreading ridge is the Gakkel Ridge on the Arctic Ocean floor, which spreads at less than , while the fastest, the East Pacific Rise near Easter Island, has a spreading rate of over
The Cook Inlet Basin The Cook Inlet Basin The Cook Inlet Basin is a northeast-trending collisional forearc basin that stretches from the Gulf of Alaska into South central Alaska, just east of the Matanuska Valley. It is located in the arc-trench gap between the Alaska-Aleutian Range batholith and contains roughly 80,000 cubic miles of sedimentary rocks. These sediments are mainly derived from Triassic, Jurassic and Cretaceous sediments. The region is heavily influenced by two major tectonic elements which are still active in the area today. The western side of the basin lies directly above the Aleutian subduction zone where the Pacific Plate is subducting