Ball P W, White N J, Maclennan J, Stephenson S N
Bullard Laboratories, Department of Earth Sciences, University of Cambridge, Madingley Rise, Cambridge, UK.
Research School of Earth Sciences, Australian National University, Canberra, ACT, Australia.
Nat Commun. 2021 Apr 6;12(1):2045. doi: 10.1038/s41467-021-22323-9.
The thermochemical structure of lithospheric and asthenospheric mantle exert primary controls on surface topography and volcanic activity. Volcanic rock compositions and mantle seismic velocities provide indirect observations of this structure. Here, we compile and analyze a global database of the distribution and composition of Neogene-Quaternary intraplate volcanic rocks. By integrating this database with seismic tomographic models, we show that intraplate volcanism is concentrated in regions characterized by slow upper mantle shear-wave velocities and by thin lithosphere (i.e. <100 km). We observe a negative correlation between shear-wave velocities at depths of 125-175 km and melt fractions inferred from volcanic rock compositions. Furthermore, mantle temperature and lithospheric thickness estimates obtained by geochemical modeling broadly agree with values determined from tomographic models that have been converted into temperature. Intraplate volcanism often occurs in regions where uplifted (but undeformed) marine sedimentary rocks are exposed. Regional elevation of these rocks can be generated by a combination of hotter asthenosphere and lithospheric thinning. Therefore, the distribution and composition of intraplate volcanic rocks through geologic time will help to probe past mantle conditions and surface processes.
岩石圈和软流圈地幔的热化学结构对地表地形和火山活动起着主要控制作用。火山岩成分和地幔地震波速度为这种结构提供了间接观测数据。在此，我们汇编并分析了一个关于新近纪 - 第四纪板内火山岩分布与成分的全球数据库。通过将该数据库与地震层析成像模型相结合，我们发现板内火山活动集中在以下区域：这些区域以上地幔剪切波速度缓慢和岩石圈薄（即<100千米）为特征。我们观察到125 - 175千米深度处的剪切波速度与根据火山岩成分推断出的熔体分数之间呈负相关。此外，通过地球化学模型获得的地幔温度和岩石圈厚度估计值与从已转换为温度的层析成像模型确定的值大致相符。板内火山活动常常发生在隆起（但未变形）的海相沉积岩出露的区域。这些岩石的区域隆升可能是由较热的软流圈和岩石圈变薄共同作用产生的。因此，地质时期板内火山岩的分布和成分将有助于探究过去的地幔状况和地表过程。
