Explain the processes occuring at constructive tectonic plate boundaries

Constructive plate boundaries occur when two tectonic plates move away from each other. These tectonic plates drift apart due to the convection currents in the magma present in the Earth's mantle which originate as the result of the heat being admitted from the Earth's core due to radioactive processes occurring here. This results in a gap in the Earth's crust to appear through magma from the mantle seeps, cools and hardens to form igneous rock. An example of this plate margin can be found in the Atlantic ocean where the mid-Atlantic ridge has been widely documented as the Eurasian and African plates drift away from the North and South American plates.