Then a supervolcano eruptions impact the climate for years or even decades as just happened with the enormous submarine supervolcano Hunga Tonga eruption in 2021/22!
"Geoscientists have long thought that water – along with shallow magma stored in Earth’s crust – drives volcanoes to erupt. Now, thanks to newly developed research tools ... scientists have learned that gaseous carbon dioxide can trigger explosive eruptions. ..."
From the significance and abstract:
"Significance
The role of intraplate volcanoes in the global volatile cycle and their potential to produce explosive eruptions are still major unknowns. Using melt inclusions (MIs) from mafic explosive eruptions from Fogo, one of the world’s most active volcanoes with highly explosive mafic eruptions, we can start answering those questions. We identified that Fogo sampled a volatile-rich mantle source and represents an important global endmember, as evidenced by MIs that record oxidized melt compositions and very high volatile concentrations (2 wt% CO2, 2.8 wt% H2O, 6,000 ppm S, 1,900 ppm F, and 1,100 ppm Cl). Our observations imply that eruptions such as these are fed directly from the mantle, bypassing shallow crustal storage, and are driven up by deep CO2 exsolution.
Abstract
Constraining the volatile content of magmas is critical to our understanding of eruptive processes and their deep Earth cycling essential to planetary habitability ... Yet, much of the work thus far on magmatic volatiles has been dedicated to understanding their cycling through subduction zones. Further, studies of intraplate mafic volcanism have disproportionately focused on Hawaii ..., making assessments of the overall role of intraplate volcanoes in the global volatile cycles a challenge. Additionally, while mafic volcanoes are the most common landform on Earth and the Solar System ... they tend to be overlooked in favor of silicic volcanoes when it comes to their potential for explosivity. Here, we report primitive (olivine-hosted, with host Magnesium number – Mg# 78 to 88%) melt inclusion (MI) data from Fogo volcano, Cabo Verde, that suggest that oceanic intraplate silica-undersaturated explosive eruptions sample volatile-rich sources. Primitive MI (melt Mg# 70 to 71%) data suggest that these melts are oxidized (NiNiO to NiNiO+1) and very high in volatiles (up to 2 wt% CO2, 2.8 wt% H2O, 6,000 ppm S, 1,900 ppm F, and 1,100 ppm Cl) making Fogo a global endmember. Storage depths calculated from these high volatile contents also imply that magma storage at Fogo occurs at mantle depths (~20 to 30 km) and that these eruptions are fed from the mantle. Our results suggest that oceanic intraplate mafic eruptions are sustained from the mantle by high volatile concentrations inherited from their source and that deep CO2 exsolution (here up to ~800 MPa) drives their ascent and explosivity."
No comments:
Post a Comment