Peak-ring structure and kinematics from a multi-disciplinary study of the Schrödinger impact basin

Abstract

The Schrödinger basin on the lunar farside is ∼320 km in diameter and the best-preserved peak-ring basin of its size in the Earth–Moon system. Here we present spectral and photogeologic analyses of data from the Moon Mineralogy Mapper instrument on the Chandrayaan-1 spacecraft and the Lunar Reconnaissance Orbiter Camera (LROC) on the LRO spacecraft, which indicates the peak ring is composed of anorthositic, noritic and troctolitic lithologies that were juxtaposed by several cross-cutting faults during peak-ring formation. Hydrocode simulations indicate the lithologies were uplifted from depths up to 30 km, representing the crust of the lunar farside. Through combining geological and remote-sensing observations with numerical modelling, we show that a Displaced Structural Uplift model is best for peak rings, including that in the K–T Chicxulub impact crater on Earth. These results may help guide sample selection in lunar sample return missions that are being studied for the multi-agency International Space Exploration Coordination Group.

The formation of peak rings in large impact craters

“…These simulations suggest that, as crater size increases, the rocks that form peak rings originate from increasingly deeper depths (38). This relationship means that the composition of the peak-ring lithology provides information on the crustal composition and layering of planetary bodies, and be used to verify formation models, such as for the Moon (e.g., 6,[38][39]. One of the principal observations used to support a version of the nested melt-cavity hypothesis in Baker et al (7) is that peak rings within basins of all sizes on the Moon contain abundant crystalline anorthosite and must, therefore, originate from the upper crust if indeed the lower crust is noritic.…”

“…These simulations suggest that, as crater size increases, the rocks that form peak rings originate from increasingly deeper depths (38). This relationship means that the composition of the peak-ring lithology provides information on the crustal composition and layering of planetary bodies, and be used to verify formation models, such as for the Moon (e.g., 6,[38][39].…”

“…Recovery and Interior Laboratory (GRAIL) mission results of a highly porous lunar crust (42) and the presence of mid-crustal rocks juxtaposed by shear zones in the peak ring at Schrödinger crater (38). This linkage between deformation and overturning of material at the scales > 10 km implies that over an extended period of time impact cratering greatly increases the porosity of the subsurface and cause vertical fluxes of materials within the crust.…”

Ring faults and ring dikes around the Orientale basin on the Moon

“…In terms of the gross structure of the main basin rings, Chicxulub more closely resembles a peak ring basin such as Schrödinger (Baker et al, 2017;Kring et al, 2016) or Schwarzschild, rather than a multiring basin such as Orientale (Gulick et al, 2013), despite gravity scaling of basin diameters that would indicate otherwise. This discrepancy is consistent with expectations that the impact excavation depth relative to the lithosphere thickness should control the…”

Rock core from dinosaur-killing impact reveals how enormous craters form

“…Last month, he and his colleagues showed that, like Chicxulub, the peak ring of the Moon's 320-kilometre-wide Schrödinger crater is made of material from deep in the crust 2 . This means that robots or astronauts could visit Schrödinger to pick up samples of the lunar interior.…”