What causes stretching of the crust during continental rifting?

The stretching of the crust during continental rifting is primarily caused by the ascension of magma. As tectonic plates move apart in a rifting environment, magma from the mantle rises to fill the gap created by the diverging plates. This upward movement of magma not only contributes to the formation of new crust but also exerts pressure on the surrounding rock, leading to the stretching and thinning of the continental crust.

As the magma ascends, it causes the already present rocks to experience tensile stress, promoting fractures and a series of faults that characterize rift valleys. This process is a fundamental aspect of tectonic plate interactions, where extensional forces prevail over the surrounding material, ultimately reshaping the geological landscape.

Other factors, such as destructive forces or weathering effects, do not drive the rifting process in the same way. Destructive forces typically refer to those associated with subduction zones, while weathering pertains to the breakdown of rocks at the surface and is not directly related to the tectonic dynamics of rifting. Tectonic stability also does not relate to the active processes occurring during continental rifting, as stability implies a lack of movement, while rifting involves significant tectonic activity.