October 2025 LIP of the Month

Reconstructing past asthenospheric flow using Poiseuille models and observations from large igneous provinces: implications for continental rifting

Ingo L. Stotz

Ludwig-Maximilians-Universität (LMU) München , Theresienstrasse 41, 80333 München, Germany. Email: ingo.stotz@lmu.de

This report is based on and adapted from the following published articles; full details can be found therein,

Stotz, I. L., Vilacís, B., Hayek, J. N. and Bunge, H.-P. (2025). Continental rift driven by asthenosphere flow and lithosphere weakening by flood basalts: South america and africa cenozoic rifting. Minerals 15(6), 644. URL https://www.mdpi.com/2075-163X/15/6/644.

Stotz, I. L. (2025). Predictions of asthenosphere flow from couette/poiseuille models compared to seismic anisotropy and mantle circulation models. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 481(20250085), 20250085. URL http://doi.org/10.1098/rspa.2025.0085.

Abstract

We can now estimate how the asthenosphere—the mechanically weak, flowing layer beneath Earth’s tectonic plates—moved in the past. By combining a simple mathematical model with information about when and where large volcanic regions formed, we can better understand how the asthenosphere flow has rifted continents apart. In Stotz et al. (2025), we explore how rising plumes of hot rock from deep inside Earth helped to pull apart the ancient supercontinent of West Gondwana. Evidence from rocks, sediments, and volcanic activity suggests that plumes beneath the boundary between South America and Africa played a key role. In Stotz (2025), I show that simple flow models can describe how the asthenosphere moves today and in the past. When combined with computer simulations, these models give new insights into how movement deep within Earth shapes the motion of the continents above. Ultimately, this approach provides a theoretical estimate of past mantle flow in agreement with observations.

Introduction

Understanding the internal dynamics, structure, and composition of our planet is a fundamental goal in Earth science. Geodynamic modelling has played a key role in this endeavour, offering a theoretical window into the Earth’s convecting mantle at present-day and in the past. Figure 1A shows the streamlines of the velocity field from a numerical simulation and the light yellow colour emphasizes fast flow velocities concentrated in the upper boundary—i.e., the asthenosphere. This fast asthenospheric flow can facilitate the lateral transport of plume material over considerable distances (1000 to 10000 km) within relatively short geological timescales (< 10 Myrs) (e.g., Morgan, 1972; Hartley et al., 2011; Stotz et al., 2021; Brown et al., 2022; Vilacís et al., 2022).

By now it is well recognised that it is useful to describe asthenosphere flow in the context of Couette and Poiseuille flows (Hoeink & Lenardic, 2008, 2010; Stotz et al., 2018, 2021, 2023, 2024). This allows for analytical solutions of the flow (i.e., Stotz et al., 2021, 2023, 2024). The former arises from simple shear driven by plate tectonic movements (Figure 1B), while the latter is initiated by lateral pressure gradients (Figure 1C). Figure 1D shows the combination of Poiseuille and Couette flow. The relative importance of Couette to Poiseuille flow depends upon the degree to which plates locally inhibit or drive underlying asthenosphere flow (e.g., Brune, 2018). Importantly, the Poiseuille/Couette flow type relates vertical plate motion changes explicitly to pressure variations in the asthenosphere (Stotz et al., 2021; Vilacís et al., 2022). Thus, it connects changes in plate motion to variations in dynamic topography in a testable manner, as shown early on for the South Atlantic region (e.g., Colli et al., 2014). One source of Poiseuille flow in the asthenosphere is triggered by mantle plumes, as argued early on by Morgan (1972). A pressure driven flow can also arise from the flux generated by subducting slabs, previously referred to as slab-suction (Conrad & Lithgow-Bertelloni, 2002). Poiseuille and Couette flow models offer interpretable predictions for asthenospheric flow patterns; where the model is likely to match observations and where differences might arise. This approach enables the testing of various tectonic scenarios, both present and past. One could evaluate the relative importance of various plume fluxes at present and in the past, or investigate the paleo-locations of subduction zones derived from different plate reconstruction models, including those by Müller et al. (2022) and Chen et al. (2019, 2024).

In a duet of studies, I demonstrated that it is possible to estimate past asthenosphere flow, using an analytical model in combination with information of LIP emplacements, and thus drive plate tectonics. In Stotz et al. (2025), we test the hypothesis that the dispersal of West Gondwana plate was driven by the action of mantle plumes. In particular, we argue for the Cape Verde, Fernando, Ascension, Santa Elena and Tristan plumes, which lie on the continental boundary between South America and Africa. We base this hypothesis on observations from sedimentary records, plate motions and the dyke emplacement of large igneous provinces. In Stotz (2025), I show for the first time that fundamental analytical models of Poiseuille and Couette regimes can be used to predict global asthenosphere flow at present-day and for the past. Moreover, pairing the analytical model with numerical simulations of mantle convection provides a deeper insight into the dynamics of mantle flow behavior at present-day and enables a testable prediction of past mantle flow.

Plume influence on rifting: evidence from stratigraphy, large igneous provinces and flow modelling

Rifting of the West Gondawana plate began in the Early Cretaceous (Figure 2A), when it started to separate into multiple continents, i.e., South America and Africa. These events are coincidental with widespread emplacement of igneous volcanic rocks, both extrusive and intrusive, derived from mantle plume processes (Coffin & Eldholm, 1992), and several phases of uplift and burial (Burke & Gunnell, 2008). In Stotz et al. (2025) we argue that the rifting was driven by the plume located at the margin of South American and African continents (Figure 2A).

Plumes produce a dynamic uplift signal on the Earth’s lithosphere. This can be seen in the stratigraphic record via hiatuses. Such concept works as follows: as plumes rise from the core-mantle boundary towards the surface, they generate dynamic uplift of the surface. This, in turn generates no deposition or erosion and leaves a gap in the sedimentary record. If the plume is deep in the mantle, its upwelling signal will be of low amplitude and large areal extent, while closer to the surface the uplift signal increases in amplitude but decreases in areal extent. This sequence of events leaves a characteristic sedimentary signature that can be mapped on continental regions, as described by Friedrich et al. (2018), Friedrich (2019) and documented in a series of studies by Hayek et al. (2020), Vilacís et al. (2022) and Vilacís et al. (2024). Figure 2B shows the hiatus surfaces for the West Gondwana continent in the late Jurassic, which extend all along the coast that connects these two continents together. Red/blue colours indicate high/low topography on the series in question. Blank regions indicate the absence of the series in question and its immediately preceding unit. The wide distribution of hiatus surfaces in the late Jurassic indicates that plume pulses occurred during the early Cretaceous, accompanied by widespread volcanic activity.

Plume-driven eruptions produce vast voluminous regions of mafic igneous extrusive and intrusive rocks on Earth’s surface, now recognized as large igneous provinces (LIPs) (e.g., Coffin & Eldholm, 1992; Ernst & Buchan, 2002; Coffin & Eldholm, 2019; Ernst et al., 2021). There is an apparent temporal correlation between LIPs emplacement and global environmental crises (climate), including mass extinctions (Kasbohm et al., 2021). Figure 2C illustrates the extent of LIP events across West Gondwana during the rifting period. The opening of the South Atlantic followed the emplacement of vast amounts of mafic igneous extrusive and intrusive rocks associated with the central Atlantic magmatic province (CAMP) in the late Triassic to Jurassic (e.g., Baksi, 2003; Whalen et al., 2015). This triggered the formation of multiple dyke swarms across northern South America and northwestern Africa (e.g., Ernst & Buchan, 1997; Marzoli et al., 1999). The Karoo igneous province consists of Jurassic basaltic rocks preserved in southern Africa (e.g., Cox, 1988), and its counterpart, the Ferrar province extends from Antarctica, Australia to New Zealand (e.g., Segev, 2002). Southern Africa has several dykes dating to this time (e.g., Burke & Dewey, 1973; Ernst & Buchan, 1997). These two vast magmatic events left the northern and southern portions of Africa and, also, South America filled with intrusive dykes. The Early Cretaceous Paraná-Etendeka flood basalts suggest that the primary magmatic phase occurred between approximately ∼138 and ∼121 Ma (Piccirillo et al., 1988; Peate, 1997), with subsequent volcanic activity recorded up to 90 and 83 Ma (Segev, 2002). This event was nearly simultaneous with emplacement of the equatorial magmatic province (EQUAMP). Its main phase of eruptions occurred between ∼138 Ma and ∼81 Ma, with some younger eruptive periods of eruptions dated at ∼75-70 Ma and ∼68-49 Ma (Segev, 2002; Hollanda et al., 2019). The extent and long duration of these large igneous provinces are related to the plume activity in the region (Figure 2A).

Asthenospheric flow as a driver of continental rifting

Here we make a prediction of asthenosphere flow beneath the West Gondwana plate based on the Poiseuille flow model (Stotz et al., 2025; Stotz, 2025). The asthenosphere is assumed to be of uniform thickness with a constant viscosity beneath non-deforming plates. The plume Poiseuille flow beneath the West Gondwana plate spreads radially from each plume center, decreasing in intensity with distance. It occurs within an asthenospheric channel characterized by zero velocity at its upper and lower boundaries. The flow velocity is maximum near the location of the plumes, particularly where multiple plumes converge. The plume flow has regional components and is still characterized by a long wavelength, see Figure 3A. The flow also shows divergence at the common coastline of the South American and African continents. The slab Poiseuille flow is maximum near the subduction zone and decreases in intensity with distance. In particular, the minimum slab flow velocity beneath West Gondwana is near the ridges near Antarctica and India (Figure 3B). The slab Poiseuille flow is characterized by a smooth and long wavelength pattern. It is also characterized by divergence near the southern ridge near Antarctica and Madagascar.

Then, by combining these two flow regimes (plumes and slabs), the total Poiseuille flow in the asthenosphere is constructed and shown in Figure 3C. This is by construction (i.e., Vpoiseuille = Vplumes + Vslabs). The superposition of these two flow regimes can generate asthenosphere flow velocities up to ∼20 cm/yr (for a thickness of 110 km and a viscosity of 5·1019 Pa·s). The fastest asthenosphere flow velocities are near the plume centres and near the subduction zones. This fast flow is due to the combination of extensive subduction margins along the western and northeastern boundaries of the West Gondawana plate and the combined effect of the five plumes within the plate. In particular, the Poiseuille flow beneath the South American plate is predominantly westward, while beneath the African plate the flow is predominantly northeastward. This flow has a nearly constant velocity throughout the area, due to the combined action of the plumes and slabs. It is also characterized by divergence close to the coastlines that connect South America to the African continent. In Stotz et al. (2025), we showed that the torque generated solely by the rapid flow of mantle plumes is sufficient to drive the rifting between South America and Africa.

The events leading to the rifting of the West Gondwana plate into South American and African are summarized in Figure 4. Beneath the West Gondwana continent, rising plumes induce lithospheric uplift (Figure 4A), a process that is supported by stratigraphic records in South America and Africa (Figure 2B). Once plumes reach the asthenosphere, they will generate large amounts of igneous rock eruptions in the lithosphere at the surface (Figure 4B). The distinct provinces of major eruptions across West Gondwana serve as a proxy for the intensity and extent of plume activity during the late Cretaceous (Figure 2C). The channelized nature of the asthenosphere allows the development of fast plume flow and strong divergent currents below tectonic plates (Figure 4C). Thus plume Poiseuille flow is the most straightforward mechanism for rifting the lithosphere.

Past asthenospheric flow: insights from analytical models and evidence from large igneous provinces

A fundamental task of Earth science is to reconstruct mantle flow histories, so that they can be tested against observations from the geological record. This can be accomplished numerically through the use of adjoint techniques (e.g., Ghelichkhan et al., 2024). Adjoint models incorporate the complexities of a forward model, i.e. MCMs, within an inverse problem. This added complexity makes it attractive to derive quantitative expectations for past mantle flow, at least within the asthenosphere. The analytical approach presented here makes this possible.

Focussing on the last 120 Myrs (i.e., about one mantle transient time), I use as input a plate motion history for the Couette component, and the paleo location of subducting margins and locations and records of volcanic activity related to plumes (i.e, eruption of large igneous provinces) for the Poiseuille component. The Couette flow is obtained from the global kinematic reconstruction by Müller et al. (2022). The slab Poiseuille flow is obtained from paleo location of subducting margins (Müller et al., 2022). Previous studies exploited continental stratigraphy (e.g., Vilacís et al., 2022) to estimate the regional and temporal variations of the Poiseuille component, because the latter is expressed as dynamic topography. This yielded estimates of asthenosphere flow below the Atlantic basin for the Cenozoic. But it is limited to plates with continents. Here I go one step further and estimate the past activity of plumes globally based on the emplacement of large igneous provinces (e.g., Ernst & Buchan, 2002; Stotz et al., 2024, and references therein). A simple catalog of Cretaceous/Cenozoic plume activity is listed in Figure 5.

Figure 6 presents the estimated paleo asthenosphere flow from 20 Ma to 120 Ma. The flow is time dependent, as expected, and characterised by a smooth, long-wavelength structure. It reaches velocities of more than 20 cm/yr in regions where more than one plume is presumed active at the same time, and/or where several subduction zones are located nearby. Note that alternative plate reconstruction models, such as those proposed by Chen et al. (2019, 2024) could be used and that the representation of the plume and slab flow could be further improved— for example by assigning regional and temporal variations in slab flux. In other words, the analytical model makes it straight forward to explore a number of hypotheses that bear on past asthenosphere flow.

Conclusion

Computer models are increasingly used to study how Earth’s interior moves and evolves. However, interpreting these complex models and comparing them with real geological and geophysical data remains challenging. In geodynamics, a key goal is to understand how mantle flow shapes Earth’s surface over time. Here we had a look at a simple analytical model that describes how material flows within the asthenosphere beneath the tectonic plates. The results suggest that two types of flow, known as Poiseuille (pressure-driven) and Couette (shear-driven), are both essential parts of asthenosphere flow. Because it is easy to compute, this analytical model helps interpret results from more complex numerical simulations. It can also be applied to past time periods, offering new insights into how mantle flow may have evolved through Earth’s history. Notably, Poiseuille flow within the asthenosphere offers a simple yet powerful mechanism to explain continental rifting and plate motions.

References