@article{fdi:010090568,
  title = {{I}nsights into {V}enus' crustal plateaus from dyke trajectories below craters},
  author = {{L}e {C}ontellec, {A}. and {M}ichaut, {C}. and {M}accaferri, {F}. and {P}inel, {V}irginie and {C}hambat, {F}. and {S}mrekar, {S}.},
  editor = {},
  language = {{ENG}},
  abstract = {{O}n {V}enus, radar observations of the surface have highlighted two categories of craters: bright-floored, interpreted as pristine, and dark-floored, interpreted as being partially filled by lava. {W}hile volcanic resurfacing occurs within and outside craters in the plains, it seems mainly concentrated within the interior of dark-floored craters in the crustal plateaus, suggesting that the magma is negatively buoyant there. {I}ndeed, crater unloading may facilitate vertical ascent of a negatively buoyant magma by decompressing the underlying crust. {H}owever, the crater topography also generates a shear stress which would tend to horizontalize the vertical propagation of a dyke. {W}e use numerical simulations of magma ascent in an axisymmetric crater stress field to demonstrate that, depending on the crust thickness and the magma-crust density contrast, a negatively buoyant magma can indeed erupt only in the crater interior while remaining stored in the crust elsewhere. {I}n particular, we identify four different behaviors depending on if and where a magma-filled crack ascending below a crater reaches the surface. {W}e draw a regime diagram as a function of two characteristic dimensionless numbers. {F}or eruption to occur only in the crater interior requires a crust thinner than 45 km and a limited range of magma-crust density contrasts, between 40 and 280 kg m-3 for crust thicknesses between 20 and 45 km, the permissible range decreasing for increasing crustal thicknesses. {T}hese results suggest that the crustal plateaus may not be particularly thick and could be slightly differentiated, but probably not very felsic. {T}he {M}agellan mission revealed two categories of impact craters at the surface of {V}enus: the pristine bright-floored and the dark-floored craters, which are interpreted as craters partially filled by smooth lava after their formation. {I}n the crustal plateaus of {V}enus, the magma reaches the surface mainly within craters, suggesting that it is denser than the crust. {B}ecause of the crater negative topography, the underlying crust is decompressed relative to its surroundings, which, in turn, facilitates magma ascent below the crater despite its negative buoyancy. {W}e first gather surface observations on a set of craters located in the crustal plateaus of {V}enus to construct a characteristic fresh crater topography. {W}e then use a model of magma ascent below a crater in the crust of {V}enus to constrain the magma and crust densities as well as the initial magma storage depth that allow for magma eruption within the crater interior only. {W}e show that magma reaches the surface only in the interior of the crater if the crust is slightly less dense than the magma and if it is not too thick (<= 45 km in thickness). {W}e identify four different behaviors for magma-filled crack propagation below craters {W}e draw a behavior diagram as a function of two dimensionless numbers characterizing dyke propagation below a crater {M}agma infilling of dark-floored craters in {V}enus' plateaus requires a crustal thickness <= 45 km and a small crust-magma density contrast},
  keywords = {{V}enus ; volcanism ; crustal plateaus ; dyke propagation ; impact crater},
  booktitle = {},
  journal = {{J}ournal of {G}eophysical {R}esearch : {P}lanets},
  volume = {129},
  numero = {5},
  pages = {e2023{JE}008189 [25 ]},
  ISSN = {2169-9097},
  year = {2024},
  DOI = {10.1029/2023je008189},
  URL = {https://www.documentation.ird.fr/hor/fdi:010090568},
}