Posted on | July 2, 2011 | Comments Off
Small-scale convection at the base of the Pacific plate has been simulated in a model of mantle plume dynamics, enabling researchers to explain the complex set of observations at the Hawaiian hotspot, according to a new study posted online in the June 26 edition of Nature Geoscience.
“A range of observations cannot be explained by the classical version of the mantle plume concept,” says Maxim Ballmer, post doctoral researcher in Mānoa’s School of Ocean and Earth Science and Technology. These observations include the occurrence of secondary volcanism away from the hotspot (e.g., Diamond Head, Punchbowl, Hanauma Bay), as well as the chemical asymmetry (Mauna Loa compared to Mauna Kea) and temporal variability (over timescales greater than 10,000,000 years) of hotspot volcanism itself.
Ballmer and colleagues, including advisor Garrett Ito, associate professor in the Department of Geology and Geophysics, designed a geodynamic model of the mantle that successfully predicts a large range of observations thus providing insight into the composition and dynamics of the mantle. Ballmer says the findings of their model, “make an important contribution toward understanding the origin of volcanism away from plate boundaries.”
“This is a long-standing question in our community that potentially provides general insight into the dynamics of our planet, and particularly into the make-up of the deepest mantle, from where mantle plumes originate,” says Ballmer. “For many reasons, understanding the deepest mantle is relevant for questions about the early days of Earth, and the origin of water and life.”
These findings came as a bit of a surprise. Although small-scale convection was one hypothesis for explaining late-stage rejuvenated volcanism on the islands. “This study is the first to qualitatively explore this mechanism and to show that it can explain both rejuvenated as well as arch volcanism, well away from the islands,” says Ito.