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How did the opening of the Atlantic Ocean create new oceanic crust?

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Earth's lithosphere and upper mantle — oceanic crust A cross section of Earth's outer layers, from the crust through the lower mantle.

The opening of the Atlantic Ocean created new oceanic crust through the process of seafloor spreading, a fundamental mechanism of plate tectonics.12

As the supercontinent Pangea began to break apart approximately 180 million years ago, the landmasses separated, creating a rift zone. This rifting allowed magma from the Earth’s mantle to rise and extrude onto the surface at the Mid-Atlantic Ridge. As this material cooled, it formed new oceanic crust composed primarily of basalt and gabbro.123

This process is continuous: as the plates move in opposite directions, the ridge acts as a spreading center where new crust is constantly produced, effectively widening the Atlantic basin. Evidence for this is found in the age of the seafloor, which is notably younger near the ridge than at the distant continental margins.31