... I really wish it were that simple. I realized things get complicated as I tried to draw a cartoon representation of the Hawaiian plume. I felt like I would be well-prepared for the task because once a week I get to sit around with some awesome geophysics graduate students and we talk about a couple of plume-related papers we all agreed to read. But I think that reading these papers made me realize that although mantle plumes seem simple when taught in class, they are not.
The diagram started out OK. I attached a picture of Hawaii to the surface and then I labeled the relevant layers of the Earth, like the crust and the mantle etc.
And since we are pretty sure that the mantle flows, I wanted to add an arrow showing that flow in the asthenosphere, and had to look up some papers showing the direction of mantle flow in the near Hawaii so I could point the arrow in the right direction.
But then I started drawing the plume and things really went downhill from there. For starters, there is still a minority in the scientific community that contests the existence of plumes, and there is still some uncertainty over exactly where the bottom of the Hawaiian plume is located (e.g. Montelli et al., 2004; Foulger and Natland, 2003). However, the majority of the literature seemed to view Hawaii as a deeply-rooted mantle plume, and even as an "archetypal" mantle plume, so I decided to draw the plume as a tube of hot material rising from the core-mantle boundary (e.g. Courtillot et al., 2003).
But I gradually realized that, in this cartoon picture, it would really be difficult to do an excellent representation of the Hawaiian plume. Factors that I decided I couldn't represent included (1) the fact that the plume probably doesn't go perfectly straight up from the core-mantle boundary to the surface, (2) the size/width of the plume probably changes with depth, (3) there is probably some significant change in the plume structure at important transition zones like the lithosphere-asthenosphere boundary, (4) mantle flow around the Hawaiian plume is more complicated than a single arrow, and convection may be layered. While I would like to draw a picture of the Hawaiian plume interacting with mantle flow that took into account all of these features, I don't think I can.
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