Mantle plumes are key drivers of volcanism within tectonic plates. Variations in plume flux and the resulting magma flux are expected within a plume’s lifetime, but their impact on volcanic architecture and eruption products and styles remains poorly constrained. Here we combine mineralogy, petrology and geochronology of Earth’s longest continental hotspot chain to assess the effects of waning plume strength on magma flux and pre-eruptive magma transport and storage. We focus on Cenozoic age-progressive volcanoes across eastern Australia, divided by a change in plate motion and voluminous volcanism. Northern volcanoes are older and ‘long-lived’ (3.5–7 million years (Ma)) and erupted high volumes (>800 km³) of bimodal magmas (basalts and rhyolites), producing homogeneous, crystal-poor basalts (~3 vol% phenocrysts). Southern volcanoes are smaller (<300 km³), ‘short-lived’ (≤1.5 Ma) and split into two parallel tracks that erupted more evolved and texturally complex magmas (~12 vol% phenocrysts, internally zoned). These findings imply waning magma flux leads to increasingly complex feeder systems that enhance magma storage and differentiation. Similar trends in hotspot tracks globally suggest that plume and magma flux play a crucial role in the evolution of intraplate volcanoes.

地幔柱是构造板块内火山活动的主要驱动力。羽流的变化和由此产生的岩浆流在羽流的生命周期内是预期的，但它们对火山结构和喷发产物和样式的影响仍然没有得到很好的限制。在这里，我们结合地球最长大陆热点链的矿物学、岩石学和地质年代学，评估逐渐减弱的羽流强度对岩浆通量和喷发前岩浆运输和储存的影响。我们关注澳大利亚东部的新生代年龄渐进火山，除以板块运动和大量火山活动的变化。北部火山较老且“长寿”（350 万至 700 万年 (Ma)）并喷发大量 (>800 km³) 双峰岩浆（玄武岩和流纹岩），产生均质、贫晶玄武岩（~3 vol%斑晶）。南部火山较小（<300 km³），“寿命短”（≤1.5 Ma）并分成两条平行轨道，喷出更多演化和结构复杂的岩浆（~12 vol% 斑晶，内部分区）。这些发现意味着岩浆通量的减弱导致供给系统越来越复杂，从而增强了岩浆的储存和分化。全球热点轨迹的类似趋势表明，羽流和岩浆通量在板内火山的演化中起着至关重要的作用。