研究小组报道了来自佛得角Fogo火山的原始熔融包裹体(MI)数据(以橄榄石为主体，主体镁数—Mg # 78-88%)，这些数据表明大洋板块内二氧化硅的不饱和喷发取样富含挥发性物质的来源。原始熔融包裹体(熔融 Mg # 70-71%)的数据表明，这些熔融物被氧化(NiNiO-NiNiO+1)，挥发物含量非常高(高达2 wt%的CO2，2.8 wt%的H2O，6,000 ppm的S，1,900 ppm F 和 1,100 ppm 的Cl)，使得Fogo成为一个全球性的端元。根据这些高挥发性成分计算出的存储深度也意味着Fogo的岩浆存储发生在约20-30 km地幔深度，即这些火山喷发来自地幔。研究结果表明，大洋板内镁铁质火山喷发是由地幔，通过从其源头继承的高挥发浓度维持的，并且深部二氧化碳的出溶(这里高达约800 MPa)驱动其上升和喷发性。
据介绍，限制岩浆的挥发性成分对人们理解喷发过程及其对行星可居住性十分关键的地球深部循环至关重要。然而，到目前为止，有关岩浆挥发性成分的大部分的工作都致力于了解它们在俯冲带的循环。此外，对板内的镁铁质火山作用的不成比例的研究集中在夏威夷，使得评估板内火山在全球波动周期中的总体作用成为一项挑战。另外，虽然镁铁质火山是地球和太阳系中最常见的地貌，但当涉及到它们的潜在喷发性时，因有利于形成硅质火山往往被忽略。
附：英文原文
Title: Oceanic intraplate explosive eruptions fed directly from the mantle
Author: DeVitre, Charlotte L., Gazel, Esteban, Ramalho, Ricardo S., Venugopal, Swetha, Steele-MacInnis, Matthew, Hua, Junlin, Allison, Chelsea M., Moore, Lowell R., Carracedo, Juan Carlos, Monteleone, Brian
Issue&Volume: 2023-8-7
Abstract: Constraining the volatile content of magmas is critical to our understanding of eruptive processes and their deep Earth cycling essential to planetary habitability [R. Dasgupta, M. M. Hirschmann, Earth Planet. Sci. Lett. 298, 1 (2010)]. 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 [P. E. Wieser et al., Geochem. Geophys. Geosyst. 22, e2020GC009364 (2021)], 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 [C. A. Wood, J. Volcanol. Geotherm. Res. 7, 387–413 (1980)], 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.
DOI: 10.1073/pnas.2302093120
Source: https://www.pnas.org/doi/10.1073/pnas.2302093120