Science and Technology term | Underwater expansion

Underwater expansion

Sea Floor Spreading

Definition: Due to the flow of the mantle, the basalt magma pours and cools from the ocean ridge, forming a new shell, promoting the early formation of the ocean shell to move to both sides. At the same time The process of shell material cycle.

Discipline: Ocean Science_Oero Geology, Marine Earth Physics, Marine Geography and Kawaguchi Coast Studies

Related noun: Mantle Mantra against flowing Xuanwu Rock

Picture source: Visual China

【Extended Reading】

Underwater expansion theory is a doctrine of marine crust growth and motion expansion, and it is the further development of mainland drift theory. It was proposed by the US marine geologist H.H. Hess and R.S. Ditz respectively in the 1960s. This theory lays the foundation for the rise of plate structure and triggers a revolution in Earth Science.

The underwater expansion believes that the high -heat mantle material rises along the fracture valley of the ocean and the ridge of the ocean, constantly forming a new ocean shell; at the same time, the border of the ocean mid -ridge is the boundary. The sinking sinking of the gap of the ocean, driving the shell to sneak into the mantle and being digested and absorbed.

Different expansion of the ocean is different. For example, the Atlantic Ocean expands at the ocean ridge in the center of the ocean. The reduction of the dive zone around the ocean has a peculiar phenomenon of dive and removal, which makes the Pacific Ocean the fastest underwater expansion, but the overall area is gradually narrowing.

Underwater expansion effects are expanding on both sides of the axis of the ocean spine, which is usually used to indicate the expansion rate on one side, that is, the semi -expansion rate. The calculation results show that the semi -expansion rate of the Pacific Ocean is 5 to 7 cm per year, and the semi -expansion rate of the Atlantic Ocean is 1 to 2 cm per year. After 20 to 300 million years of changes in the ocean floor, there will be a huge change in updated.

The underwater expansion said that it is better to explain a series of physical phenomena of the underwater geological earth. Its establishment makes the continental drift theory from declining, and the activity theory that advocates large -scale horizontal movement has achieved victory. However, the underwater expansion is still in terms of expansion mechanism to be solved.

(Dr. Zhao Qiang, the First Ocean Research Institute of the Ministry of Natural Resources)

Source: National Scientific and Technological Noun Review Committee

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