Beneath the continents, far below the crust and upper mantle that most geological models focus on, slow-moving columns of anomalously hot rock rise from near the core–mantle boundary. These mantle plumes are not surface phenomena. They originate thousands of kilometers down, where temperature contrasts and buoyancy allow massive volumes of material to ascend over tens of millions of years. When they reach the base of the lithosphere, they spread laterally, decompress, and partially melt. If conditions allow, that melt erupts at the surface in quantities that dwarf normal volcanic systems. The result is what geologists call a large igneous province.
Large igneous provinces are defined by their scale. They are not typical volcanic arcs or isolated hotspot chains. They involve millions of cubic kilometers of magma emplaced over relatively short geological intervals. Flood basalts can cover areas the size of nations. Intrusive complexes penetrate deep into continental crust. Gas release from these systems can alter atmospheric chemistry and ocean structure on a global scale.
Several of Earth’s largest biological crises coincide with these events. Around 252 million years ago, the Siberian Traps erupted across what is now northern Russia. This magmatic episode is temporally associated with the end-Permian mass extinction, the most severe biotic crisis in Earth history. An estimated majority of marine species and a substantial fraction of terrestrial life disappeared. The eruption volume was immense, and geochemical evidence indicates sustained carbon dioxide release, sulfur emissions, and thermogenic gas generation as magma intruded organic-rich sediments.
At approximately 201 million years ago, the Central Atlantic Magmatic Province formed during the breakup of Pangea. This event aligns with the end-Triassic extinction. Flood basalts erupted across multiple continents that were then joined together. Rapid carbon release, climatic warming, and ocean disruption followed.
Around 66 million years ago, the Deccan Traps in India produced another major large igneous province. This eruption overlapped with the end-Cretaceous extinction interval. While an asteroid impact played a decisive role in that event, the Deccan system contributed sustained volcanic gas emissions that affected climate and atmospheric chemistry.
The association between large igneous provinces and mass extinctions is not accidental. These provinces represent deep Earth processes capable of releasing greenhouse gases and aerosols on scales sufficient to disrupt planetary systems. Carbon dioxide drives long-term warming. Sulfur dioxide can cause short-term cooling followed by acid deposition. Ocean chemistry shifts as dissolved carbon increases. Marine anoxia develops when warming reduces oxygen solubility and alters circulation. Ecosystems collapse under compounded stress.
Yet mantle plumes do not automatically generate extinction-level events. The outcome depends on how plume material interacts with the lithosphere. The lithosphere is not uniform. Continental blocks vary in thickness, strength, and thermal structure. Some regions possess thick, cold cratonic roots extending more than 150 kilometers into the mantle. Other regions, particularly orogenic belts and previously stretched crust, have thinner lithosphere. These differences matter.
When a plume head rises beneath a continent, it encounters the base of this heterogeneous lithosphere. If the lithosphere is thick and mechanically strong, it can inhibit vertical melt ascent. Plume material may spread laterally beneath it, deflecting along zones of lower resistance. If the lithosphere is thinner, decompression melting is enhanced, and magma can more easily penetrate upward. Pre-existing structural weaknesses, such as deep faults and sutures, further localize ascent.
This structural control influences both the volume and distribution of surface volcanism. A plume beneath uniformly thin lithosphere may generate broad, radially distributed flood basalts. A plume interacting with thick cratonic keels may produce asymmetric magmatic footprints, concentrated corridors of intrusion, and prolonged sub-lithospheric ponding before eruption. These differences affect the rate of gas release, the duration of volcanism, and the degree of environmental stress imposed on the biosphere.
The Tarim Large Igneous Province of northwestern China provides an example of this interaction in the geological record. Formed during the Early Permian, it developed along the margin of a craton adjacent to an orogenic belt. Geochemical analysis of basaltic rocks shows varying affinities to plume-derived and subduction-modified mantle sources across the region. Recent analytical approaches using machine learning classification of major and trace element data indicate that plume signatures decrease northward from the craton into the adjacent orogen. This pattern suggests that lithospheric architecture modulated plume spread.
Reconstruction of lithospheric thickness using geochemical proxies indicates that thinner zones coincided with stronger plume-related signatures, while thicker blocks corresponded with suppressed plume influence. In practical terms, variations on the order of tens of kilometers in lithospheric thickness were sufficient to redirect plume material laterally over distances exceeding several hundred kilometers. Thick lithospheric regions acted as barriers. Thin regions functioned as channels. Deep faults provided vertical pathways for melt ascent.
This framework clarifies why large igneous provinces are often located near craton margins rather than centered within the thickest continental interiors. The margin represents a transition zone between strong lithospheric keels and weaker, thinner belts. That transition promotes lateral plume flow and focused melt extraction. It also explains why magmatism associated with a plume may not appear uniformly distributed, even when driven by a single deep mantle source.
The environmental consequences of plume events depend not only on total magma volume but also on emplacement style. Intrusive activity within sedimentary basins can generate thermogenic gases by heating carbon-rich rocks. Explosive gas release through fissure eruptions can inject aerosols high into the atmosphere. Prolonged sub-lithospheric ponding may extend volcanic activity over millions of years, sustaining climate forcing beyond a single eruptive pulse.
In the case of the Siberian Traps, intrusion into evaporite and hydrocarbon-bearing sediments likely amplified greenhouse gas release. That amplification was partly controlled by the lithospheric and sedimentary architecture of the region at the time. The same deep plume mechanism interacting with different crustal compositions could produce different atmospheric outcomes.
Understanding what controls plume spread therefore informs how extinction-scale events develop. The plume provides the thermal engine. The lithosphere dictates where and how that energy is expressed. Thickness contrasts, structural weaknesses, and crustal composition determine whether a plume produces widespread flood basalts, concentrated intrusive complexes, or a combination of both. Those differences shape the magnitude and duration of environmental disruption.
It is important to emphasize that mantle plumes operate on geological timescales. The formation of a large igneous province unfolds over hundreds of thousands to millions of years. There is no evidence of an imminent extinction-scale plume event in the present day. Modern mantle upwellings such as those beneath Iceland or Hawaii represent localized hotspots, not continental flood basalt systems of the scale associated with mass extinctions.
However, the geological record demonstrates that Earth’s interior retains the capacity for such events. The core–mantle boundary remains thermally active. Mantle convection continues. Plume generation is an intrinsic part of planetary heat loss. Over deep time, these processes recur.
The broader implication is that mass extinctions linked to volcanism were not random catastrophes. They were the surface manifestation of structured interactions between deep mantle dynamics and continental architecture. The distribution of cratons, sutures, and lithospheric thickness variations conditioned how plume energy was released.
Future research integrates high-resolution geochemical datasets, geophysical imaging of lithospheric thickness, and numerical simulations of plume ascent in heterogeneous mantle conditions. Such work refines estimates of melt volume, gas flux, and thermal evolution. It also clarifies why some plume events coincide with severe environmental crises while others do not.
Deep mantle plumes represent one of the most powerful forces in Earth history. When their ascent intersects favorable lithospheric conditions, they generate large igneous provinces capable of altering climate and reshaping life. The trigger originates thousands of kilometers below the surface. The outcome is determined in large part by the structure of the continents above.
Source:
Geoscience Frontiers (2026)
Lithospheric thickness controls asymmetric mantle plume spreading and metallogenesis in the Tarim Large Igneous Province–Central Asian Orogenic Belt System
https://doi.org/10.1016/j.gsf.2026.102249
