How do differences in density and temperature cause sea-floor spreading and subduction?

Hint: The idea of plate tectonics uses seafloor spreading to explain continental drift. Tensional stress generates fractures in the lithosphere when oceanic plates diverge. Although there is often extensive magma activity along spreading ridges, the motivational force for seafloor spreading ridges is tectonic plate slab pull at subduction zones, rather than magma pressure.

Complete answer:
Subduction occurs when the cooler, denser mantle sinks and the hotter mantle rises to the surface, producing seafloor spreading. In a convection circulation, hot material rises to the surface and begins to cool and spread out once it reaches the surface. The seafloor spreading seen near the mid-ocean ridges is caused by this.

The cooler material descends back down in a convection current, completing the cycle of the convection current. At a subduction zone, the cooler mantle material falls back into the hotter mantle, carrying the crust along with the cooler mantle section. The ocean plates are also formed of basalt, which is significantly denser than the continental plates' granite base. As a result, the ocean plate is the one that descends into the mantle.

Seafloor spreading takes place along mid-ocean ridges, which are huge mountain ranges that rise from the ocean floor. The Mid-Atlantic Ridge, for example, connects the North American and Eurasian plates, as well as the South American and African plates. The East Pacific Rise is a mid-ocean ridge that divides the Pacific plate from the North American plate, the Cocos plate, the Nazca plate, and the Antarctic plate in the eastern Pacific Ocean.

Note: Hot magma propelled by mantle convection bursts up and overflows onto the crust, filling the fissures. Igneous rock is formed when hot magma is cooled by cold seawater. This rock (basalt) is incorporated into the Earth's crust for the first time.