Mantle Plumes and Plate Tectonics PDF

Mantle plume may be defined as upwelling of ag a erti all through Earth s a tle Plume ?? which is derived from 2900 km (core mantle...

Mantle plume may be defined as upwelling of ag a erti all through Earth s a tle Plume ?? which is derived from 2900 km (core mantle boundary) or 660 km (transition zone). Although plate tectonics effectively explain Plume consists of mushroom type of head various geological processes and conduits (called as tail of plumes) Still there are some geological features which When plume reaches the base of lithosphere a t e e plai ed fro plate te to i s. its head may be about 1000 km if coming Intraplate volcanism fro D -layer which later flattened and take Ocean Island basalt the diameter of 2000 km while if plume Continental flood basalt coming from 660 km head (200 km) and will So, plume tectonics is required to explain be flattened to 1000 km. them.  Types of plume- Oceanic island chains (e.g. Hawaii) do not associated with plate boundaries and hence 1. 1° Plume (Morganian plume)--Primary a t e e plai ed te to i s. 2. 2° Plume --Secondary Oceanic island basalt are enriched in If plume starts from core- a tle D' la er incompatible elements. boundary it is called primary plume/Morganian plume while secondary plumes are derived from shallow depth (transitional zone) Hotspots Afar Azore Surface manifestation of plumes can be Bouvet termed as Hotspot. Cameron Hotspot is a location on the surface of the Eifel Earth that has experienced active volcanism Reunion for long period of time. Kerguelen The hotspots can be recognised at the site of Iceland (2° plume) volcanism that remain nearly stationary Hawaii relative to moving lithospheric plate. Tristan  Indian plate Volcanic chains like Hawaii islands results from slow movement of tectonic plate across Reunion (Deccan traps) a fixed hotspot beneath the surface of the Kerguelen (Rajmahal traps) Earth. Deccan traps are result of drifting of Indian plate across Reunion hotspot. Past movement of plates can be marked by hotspots. Rajmahal traps are result of interaction of Indian plate and Kerguelen hotspot. Plumes are generated due to instability Temperature of plume may be 300° C higher ithi the D la er due to- than the surrounding asthenoshpere. 1. Extraction of heat from core 2. Descending slabs into deep mantle In upward journey of plume- 1. Disturb phase transition boundary 2. Entrain mantle material 3. Impenging at base of lithosphere