<P> A supercontinent cycle is the break - up of one supercontinent and the development of another, which takes place on a global scale . Supercontinent cycles are not the same as the Wilson cycle, which is the opening and closing of an individual oceanic basin . The Wilson cycle rarely synchronizes with the timing of a supercontinent cycle . However, supercontinent cycles and Wilson cycles were both involved in the creation of Pangaea and Rodinia . </P> <P> Secular trends such as carbonatites, granulites, eclogites, and greenstone belt deformation events are all possible indicators of Precambrian supercontinent cyclicity, although the Protopangea - Paleopangea solution implies that Phanerozoic style of supercontinent cycles did not operate during these times . Also there are instances where these secular trends have a weak, uneven or lack of imprint on the supercontinent cycle; secular methods for supercontinent reconstruction will produce results that have only one explanation and each explanation for a trend must fit in with the rest . </P> <P> The causes of supercontinent assembly and dispersal are thought to be driven by convection processes in the Earth's mantle . Approximately 660 km into the mantle, a discontinuity occurs, affecting the surface crust through processes like plumes and "superplumes". When a slab of subducted crust is denser than the surrounding mantle, it sinks to the discontinuity . Once the slabs build up, they will sink through to the lower mantle in what is known as a "slab avalanche". This displacement at the discontinuity will cause the lower mantle to compensate and rise elsewhere . The rising mantle can form a plume or superplume . </P> <P> Besides having compositional effects on the upper mantle by replenishing the large - ion lithophile elements, volcanism affects plate movement . The plates will be moved towards a geoidal low perhaps where the slab avalanche occurred and pushed away from the geoidal high that can be caused by the plumes or superplumes . This causes the continents to push together to form supercontinents and was evidently the process that operated to cause the early continental crust to aggregate into Protopangea . Dispersal of supercontinents is caused by the accumulation of heat underneath the crust due to the rising of very large convection cells or plumes, and a massive heat release resulted in the final break - up of Paleopangea . Accretion occurs over geoidal lows that can be caused by avalanche slabs or the downgoing limbs of convection cells . Evidence of the accretion and dispersion of supercontinents is seen in the geological rock record . </P>

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