Superplume activity

Carbon flux by volcanic gas from island arc and by hydrothermal solution from island arc and back arc is estimated as 0.15 x 10 mol my, and (1-6) X 10 mol my, respectively (Shikazono 1995). These fluxes are smaller than subduction flux (3.7 x 10 mol my ). Therefore, it is considered that most carbon subducts to mantle. This subduction flux ((3—4) x 10 mol my ) seems larger than hydrothermal and volcanic gas flux from mid-oceanic ridge (d-2) X 10 mol my ). Therefore, it seems likely that the amoimt of carbrni in mantle reservoir increases with time and the large amounts of carbon stored in mantle may degass intermittently associated with superplume activity (Shikazono 1995). 

It is inferred that long-term global carbon cycle including subduction, mantle storage and superplume activity is in steady state, indicating that continuous and gradual degassing is unlikely. 

Finally, Condie et al. (2001) have presented evidence that the correlation between black shale deposition, paleoclimatic disturbance and mantle superplume events can be extended back to the pre-Cambrian. Particularly good correlations between environmental disturbance and mantle plume activity occur at 1.9 Ga and 2.7 Ga... 

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