Australia: The Land Where Time Began

A biography of the Australian continent 

Subduction-Induced Mantle Flow Driving Yellowstone Plume Bifurcation

According to the authors¹ there is continuing debate concerning the causes of volcanism that has been occurring in the northwestern US since 20 Ma (Hooper, Camp, Reidel & Ross, 2007). There are 3 drivers that have been suggested to explain this volcanism. One suggestion has been that the melting that accompanies plate subduction (Faccenna et al., 2010; Liu & Stegman, 2012). Another suggestion is tectonic extension and magmatism that results from the roll back of the subducting slab (Carlson, 1984; Carlson & Hart, 1997; Christiansen, Foulgar & Evans, 2002), or the Yellowstone mantle plume (Morgan 1972; Smith et al., 2009; Jordan, Grunder, Duncan & Deino, 2004). Arguments frequently used to oppose the suggestion that a plume is the origin of volcanism in this region is based on the age progression of 2 neighbouring volcanic chains, the Snake River Plain and the High Lava Plains, the age of which progresses in opposite directions. According to the authors¹ it is likely that plumes occur near subduction zones (Weinstein & Olson, 1989), though the influence of subduction on mantle plume expressions on the surface is not well understood. In this study the authors¹ have shown by use of a laboratory model that in the northwestern US the patterns of volcanism can be explained by a plume that upwells through mantle circulating in the wedge beneath a subducting zone. Their results show that the buoyant plume may be stalled, deformed or parted by the subducting plate inducing mantle flow. The authors¹ suggest plume bifurcation can reproduce the primary volcanic features that have been observed in the northwestern US, by using plausible model parameters, in particular the way in which the 2 volcanic chains progress in opposite directions. The authors¹ suggest the presence of the Yellowstone Plume in the northwestern US is supported by the results obtained from the model used in the experiment, which also highlights the power to modify the surface geology at the margins of the convergent plates that result from interactions between the plume and the subduction processes.

Sources & Further reading

1. Kincaid, C., K. A. Druken, R. W. Griffiths, and D. R. Stegman. "Bifurcation of the Yellowstone Plume Driven by Subduction-Induced Mantle Flow." Nature Geosci 6, no. 5 (05//print 2013): 395-99.