Stephenson Simon N, Ball Patrick W, Richards Fred D
Department of Earth Sciences, University of Oxford, Oxford, UK.
Department of Geosciences, Colorado State University, Fort Collins, CO, USA.
Sci Adv. 2023 Sep 8;9(36):eadf6216. doi: 10.1126/sciadv.adf6216. Epub 2023 Sep 6.
Large igneous provinces (LIPs) are formed by enormous (i.e., frequently >10 km) but short-lived magmatic events that have profound effects upon global geodynamic, tectonic, and environmental processes. Lithospheric structure is known to modulate mantle melting, yet its evolution during and after such dramatic periods of magmatism is poorly constrained. Using geochemical and seismological observations, we find that magmatism is associated with thin (i.e., ≲80 km) lithosphere and we reveal a striking positive correlation between the thickness of modern-day lithosphere beneath LIPs and time since eruption. Oceanic lithosphere rethickens to 125 km, while continental regions reach >190 km. Our results point to systematic destruction and subsequent regrowth of lithospheric mantle during and after LIP emplacement and recratonization of the continents following eruption. These insights have implications for the stability, age, and composition of ancient, thick, and chemically distinct lithospheric roots, the distribution of economic resources, and emissions of chemical species that force catastrophic environmental change.
大火成岩省（LIPs）是由巨大（即通常大于10千米）但短暂的岩浆活动形成的，这些活动对全球地球动力学、构造和环境过程产生深远影响。已知岩石圈结构会调节地幔熔融，然而在如此剧烈的岩浆活动期间及之后其演化情况却受到的限制较少。利用地球化学和地震学观测，我们发现岩浆活动与薄（即小于约80千米）岩石圈有关，并且揭示了大火成岩省下方现代岩石圈厚度与喷发后的时间之间存在显著的正相关关系。大洋岩石圈重新增厚至125千米，而大陆地区则超过190千米。我们的研究结果表明，在大火成岩省就位期间及之后，岩石圈地幔会发生系统性破坏及随后的重新生长，以及喷发后大陆的再造山作用。这些见解对于古老、厚重且化学性质不同的岩石圈根部的稳定性、年龄和组成、经济资源的分布以及导致灾难性环境变化的化学物质排放具有重要意义。
