Topic– Important Geophysical phenomena such as earthquakes, Tsunami, Volcanic activity, cyclone etc.,
1) What do you understand by mantle plumes.Discuss. Also, explain their importance in earth sciences.(250 words)
Discuss- this is an all-encompassing directive which mandates us to write in detail about the key demand of the question. we also have to discuss about the related and important aspects of the question in order to bring out a complete picture of the issue in hand.
Explain- Here we have to to make the topic clear or easy to understand by describing or giving information about it.
Key demand of the question.
The question wants us to write in detail about the mantle plumes- what they mean, how are they formed etc. We also have to describe in detail their relevance and importance for studying earth sciences.
Structure of the answer
Introduction– write a few introductory lines about mantle plumes- e.g A mantle plume is an upwelling of abnormally hot rock within the Earth’s mantle, first proposed by J. Tuzo Wilson in 1963.
- Discuss the meaning of mantle plumes in detail. E.g Convection in the mantle transports heat from the core to the Earth’s surface in thermal diapirs. Two largely independent convective processes occur in the mantle: the broad convective flow associated with plate tectonics, which is driven primarily by the sinking of cold plates of lithosphere back into the mantle asthenosphere, and mantle plumes, which carry heat upward in narrow, rising columns, driven by heat exchange across the core-mantle boundary. The latter type of convection is postulated to be independent of plate motions.A mantle plume is posited to exist where hot rock nucleates at the core-mantle boundary and rises through the Earth’s mantle becoming a diapir in the Earth’s crust. The currently active volcanic centers are known as hotspots. In particular, the concept that mantle plumes are fixed relative to one another, and anchored at the core-mantle boundary, would provide a natural explanation for the time-progressive chains of older volcanoes seen extending out from some such hot spots, such as the Hawaiian–Emperor seamount chain.
- Discuss the relevance and importance of mental plumes in studying earth sciences. E.g The narrow vertical pipe, or conduit, postulated to connect the plume head to the core-mantle boundary, is viewed as providing a continuous supply of magma to a fixed location, often referred to as a “hotspot”. As the overlying tectonic plate (lithosphere) moves over this hotspot, the eruption of magma from the fixed conduit onto the surface is expected to form a chain of volcanoes that parallels plate motion. These mantle are often invoked as the cause of volcanic hotspots, such as Hawaii or Iceland, and large igneous provinces such as the Deccan and Siberian traps. Some such volcanic regions lie far from tectonic plate boundaries, while others represent unusually large-volume volcanism near plate boundaries or in large igneous provinces etc.
Make a rough diagram to illustrate your points in a better way.
Conclusion– sum up your discussion in a few lines and form a fair and a balanced conclusion on the above issue.