The origin of the plume is unknown but likely originates in the core of the mantle boundary where there is a change in topography of a few hundred meters and where the convective liquid core loses heat by conduction. This heat source is believed to be the cause of the partial melting and may be the source of the plume. Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an original essay Plumes are believed to have a long survival period of tens of millions of years. During their ascent they manage to cross the 670 km endothermic discontinuity. Courtillot et al. (2003) suggested plume excitation by three different sources in the mantle. One type originates in the lower mantle based on chemical heterogeneity in the D layer. Another type originates at the base of transition zones that correspond to super swells. A third type originates in the upper mantle. The Courtillot model has played its role in explaining the different morphologies exhibited by plume-related volcanism. Many of the predictions, such as the size of the plume head and the nature of the associated uplift, are fundamentally dependent on the accuracy of its predictions These predictions are as follows: The new plumes consist of a large head followed by a narrower tail; the heads of the plumes are expected to flatten to form a disk 2,000-2,500 km in diameter at the top of their rise; plume should have a diameter of 100 to 200 km in the upper mantle; plume must come from a hot boundary layer, probably the core-mantle boundary; both the heads and tails should produce high-temperature magmas; The excess temperature of the plume head is expected to be significantly hotter at the center of the head than at the edge. of these predictions the most obvious is that the plumes must be warmer than the adjacent mantle. The temperature of the plumes can be obtained from the thickness of the oceanic crust produced when spreading centers overlap a plume, using the method of McKenzie & Bickle (1988) to calculate the temperature of the underlying mantle. Normally the thickness of the oceanic crust is 7 ±1 km. The thickness of the oceanic crust beneath Iceland is 40 km and 25 km beneath the Walvis Rdge, requiring the mantle temperature beneath these ridges to be 250°C and 200°C warmer than the MORB mantle, respectively. Remember: This is just a sample Get a custom paper from our expert writers now. Get a Custom Essay The most precise prediction of plume theory is that plume heads flatten to form disks 2000-2500 km in diameter when they reach the upper surface. The size of the flattened head of the plume can be obtained from the thickness of the oceanic crust. The plumes are believed to be the mechanism that initiates the early stages of continental breakup.