Erschienen in:
Earth Surface Dynamics, 7 (2019) 1, Seite 191-197
Sprache:
Englisch
DOI:
10.5194/esurf-7-191-2019
ISSN:
2196-632X
Entstehung:
Anmerkungen:
Beschreibung:
Abstract. Basalt weathering is one of many relevant processes balancing the globalcarbon cycle via land–ocean alkalinity fluxes. The CO2 consumption byweathering can be calculated using alkalinity and is often scaled withrunoff and/or temperature. Here, it is tested if the surface age distributionof a volcanic system derived by geological maps is a useful proxy forchanges in alkalinity production with time. A linear relationship between temperature normalized alkalinity fluxes andthe Holocene area fraction of a volcanic field was identified usinginformation from 33 basalt volcanic fields, with an r2=0.93. Thisrelationship is interpreted as an aging function and suggests that fluxesfrom Holocene areas are ∼10 times higher than those from oldinactive volcanic fields. However, the cause for the decrease with time isprobably a combination of effects, including a decrease in alkalinityproduction from material in the shallow critical zone as well as a declinein hydrothermal activity and magmatic CO2 contribution. The addition offresh reactive material on top of the critical zone has an effect in youngactive volcanic settings which should be accounted for, too. A comparison with global models suggests that global alkalinity fluxesconsidering Holocene basalt areas are ∼60 % higher than theaverage from these models imply. The contribution of Holocene areas to theglobal basalt alkalinity fluxes is today however only ∼5 %,because identified, mapped Holocene basalt areas cover only ∼1 %of the existing basalt areas. The large trap basalt proportion on theglobal basalt areas today reduces the relevance of the aging effect.However, the aging effect might be a relevant process during periods ofglobally intensive volcanic activity, which remains to be tested.