Corona structures driven by plume–lithosphere interactions and evidence for ongoing plume activity on Venus

Abstract

In the absence of global plate tectonics, mantle convection and plume–lithosphere interaction are the main drivers of surface deformation on Venus. Among documented tectonic structures, circular volcano-tectonic features known as coronae may be the clearest surface manifestations of mantle plumes and hold clues to the global Venusian tectonic regime. Yet, the exact processes underlying coronae formation and the reasons for their diverse morphologies remain controversial. Here we use three-dimensional thermomechanical numerical simulations of impingement of a thermal mantle plume on the Venusian lithosphere to assess the origin and diversity of large Venusian coronae. The ability of the mantle plume to penetrate into the Venusian lithosphere results in four main outcomes: lithospheric dripping, short-lived subduction, embedded plume and plume underplating. During the first three scenarios, plume penetration and spreading induce crustal thickness variations that eventually lead to a final topographic isostasy-driven topographic inversion from circular trenches surrounding elevated interiors to raised rims surrounding inner depressions, as observed on many Venusian coronae. Different corona structures may represent not only different styles of plume–lithosphere interactions but also different stages in evolution. A morphological analysis of large existing coronae leads to the conclusion that at least 37 large coronae (including the largest Artemis corona) are active, providing evidence for widespread ongoing plume activity on Venus.

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Fig. 1: Comparison of various corona morphologies on Venus with numerical simulations.
Fig. 2: Global distribution of coronae identified as inactive or showing ongoing activity.
Fig. 3: Summary of the numerical results and their dependence on the explored parameters.
Fig. 4: Evolution of a corona-forming model involving plume-induced lithospheric delamination of a weak lithosphere.
Fig. 5: Evolution of corona-forming models involving short-lived subduction (left) or plume underplating (right).
Fig. 6: Temporal evolution of radially averaged coronae topography for models representing the four identified regimes.

Data availability

The numerical data that support the findings of this study can be requested from the corresponding author. A KML file based on the coronae classification in this paper is available at Zenodo under the identifier https://zenodo.org/record/3608692 (ref. 51), and can be used in Google Earth or Google Venus. The source data of the USGS coronae nomenclature is publicly available at https://go.nature.com/2Nyp54w45 and the global topography at https://topex.ucsd.edu/pub/sandwell/google/venus49.

Code availability

The numerical code is available upon reasonable request. Requests can be made to T.V.G. (taras.gerya@erdw.ethz.ch).

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Acknowledgements

This study was co-funded by the grant NASA NNX14AG51G (L.G.J.M.), SNF grant 200021_182069 (T.V.G. and J.M.) and EU project Subitop (J.M.). All simulations were performed on the ETH-Zürich Euler cluster. The open-source software ParaView (http://www.paraview.org) was used for 3D visualizations of the experiments.

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A.J.P.G. designed the study, conducted the experiments, interpreted the numerical results and the natural data and prepared this manuscript. T.V.G. designed the study, designed the 3D thermomechanical code and interpreted the results. L.G.J.M. initiated and designed the study, and interpreted the results and natural data. J.M. contributed to the study design and conduction of the numerical experiments. All authors collaborated and contributed intellectually to this paper.

Corresponding author

Correspondence to Anna J. P. Gülcher.

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Peer review information Primary Handling Editors: Tamara Goldin; Stefan Lachowycz.

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Extended data

Extended Data Fig. 1 Global distribution of coronae (diameter > 300 km) identified as inactive (white circles), showing ongoing activity (red circles) or unclassified (grey circles).

The global topography49 is relative to 6051.877 km and is plotted on a Mollweide projection centred at 60°E longitude. Nomenclature of key areas and chasmata are shown in light text. Pink stars relate to the locations of identified raised novae structures48 proposed to be sites of ongoing plume activity25. The orange star correspond to Idunn Mons, an identified location of recently active lava flows16,74. All analysed coronae are recorded in Supplementary Table 1. A KML file containing the location of each of the coronae is available on Gülcher et al. (2020)51. The dashed lines contour our proposed areas of focused plume activity (red) or inactivity (white). The perceptually uniform scientific colour map ‘lapaz’52 was used for this figure to prevent visual distortion of the data.

Extended Data Fig. 2 Numerical model design and boundary conditions.

Details can be found in Methods description. A 2D cross-section through the centre of the model shows initial composition configuration (upper cross-section) and initial temperature distribution (lower cross-section). The vertical model boundaries in the x and z direction are symmetrical. The colour code for different materials is shown at the bottom of the figure.

Extended Data Fig. 3 Density increase of crustal material due to the basalt to eclogite phase change.

a, P-T region of the density increase due to the eclogitic phase change64, as implemented in our numerical code (see Methods) bd, Close-up on the short-term evolution of the reference model M0 (Fig. 1, main text). The density is shown in the cross-sections, and as the mantle plume pierces through the lithosphere, the lithosphere at the plume margin is pushed downwards and its density subsequently increases as it undergoes the basalt to eclogite phase change.

Extended Data Fig. 4 Evolution of a corona model in the transitional regime featuring an embedded plume (Model M2).

Model M2 has a colder initial mantle plume than the reference model, and thus a lower plume buoyancy (see Extended Data Table 2 for details of the models). a, the plume rises up to the surface, resulting in crustal uplift (at 1.88 Myr); b, the plume partially penetrates through the lithosphere but becomes embedded (at 3.24 Myr); c, the plume cools down and molten material recrystallizes, and the corona interior sinks to leave behind a raised rim (at 38.9 Myr).

Extended Data Fig. 5 Surface-strain rate for three evolutionary stages of models M9 (left), M2 (middle) and M17 (right).

See Extended Data Table 2 for details of the models. a, model M9 (reference model for ‘ephemeral subduction’ regime): the penetrating plume fully penetrates the lithosphere and crust resulting in a high strain rate, viscous corona interior in which deformation structures cannot be distinguished. Concentric deformation features at the corona margin can be recognized throughout the model evolution. The times of the snapshots correspond to those shown in Fig. 5a–c. b, model M2 (reference model for ‘embedded plume’ regime): more deformation structures can be recognized due to less melt at the surface. In addition to concentric features, stellate deformation features trace the surface in the first two stages. The timing of the snapshots corresponds to those shown in Extended Data Fig. 4. c, model M17 (also categorized as ‘embedded plume’ regime): many concentric and few radial deformation features can be observed at the surface. Important to note is that our model resolution and simplifications do not allow for a more detailed interpretation of tectonic structures at the surface and comparison thereof with observables (see Methods).

Extended Data Fig. 6 Sketches of the four geodynamic regimes identified in numerical models, during the active stage.

a, Lithospheric dripping, in which mantle plume penetration into the lithosphere is followed by delamination of lithospheric drips at the plume margins. b, Ephemeral subduction, in which a short-lived radial subduction zones follows plume impingement. The downgoing slabs eventually break off. c, Embedded plume (transitional regime), in which the plume is able to penetrate partially through the lithosphere but is terminally embedded beneath the crust. d, Plume underplating, in which the mantle plume is not able to pierce through the lithosphere but instead spreads outward beneath it.

Extended Data Fig. 7 Comparison between topographic signatures displayed by the Artemis corona (left) and the simulated coronae in model M3 at time t = 1.4 Myr (right).

colour code in both images has the same scale. The Artemis topographic profile is plotted with GMT73 based on the global topography data49. Both models show a small but clear ridge within the corona-encircling trench, characteristics in numerical models for the period shortly following lithospheric break-off/delamination and trench uplift. It is notable that the shoulders on the southeast of the figures are markedly different. This could possibly be ascribed due to the fact that the modelled case features lithospheric dripping and not subduction (as is proposed for Artemis30,31,32,43,45). Models with greater scaled crustal thicknesses (Hcrust/Hlith) have shown to produce higher-amplitude trenches and outer rises (see text).

Extended Data Fig. 8 Averaged corona surface heat flow over time (first 10 Myr of model evolution) for all numerical models in this study.

Color coding is accordingly to the regime the numerical models are assigned to (see main text and Fig. 3). More detail on the calculation of the averaged corona surface heat flow can be found in Methods. Peak heat flow reaches ~500–600 mW/m2 (plume penetrating regimes); ~200 mW/m2 (embedded plume regime), or ~50 mW/m2 (for underplated plume), but decreases significantly following peak activity.

Extended Data Table 1 Physical properties of rock materials used in the numerical experiments
Extended Data Table 2 Summary of the conditions and results of the numerical experiments

Supplementary information

Supplementary Information

Supplementary Table 1.

Supplementary Video 1

Locations of classified active and inactive coronae on the Venusian surface on a 3D rotating globe. The red circles represent active coronae and the white circles inactive coronae. The global topography45 is relative to 6,051.877 km. of ongoing plume activity25. All analysed coronae are recorded in Supplementary Table 1. A KML file containing the location of each of the coronae is available from ref. 51.

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Gülcher, A.J.P., Gerya, T.V., Montési, L.G.J. et al. Corona structures driven by plume–lithosphere interactions and evidence for ongoing plume activity on Venus. Nat. Geosci. 13, 547–554 (2020). https://doi.org/10.1038/s41561-020-0606-1

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