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Schrödinger Basin is the second youngest lunar basin, and was produced in the oldest and largest lunar basin, South Pole-Aitken (SPA). Schrödinger has been targeted as an ideal location for a future landing site because it may provide: 1) ages (for SPA and Schrödinger) that bracket the basin-forming epoch, 2) samples of the lower crust and potentially mantle, and 3) volcanic materials in younger mare and/or pyroclastic erupted deposits on its floor.
The basin formation and history described herein used crater scaling models supported by geomorphological and spectroscopic evidence from LRO and M3 data. Based on a final basin diameter of 320 km, the Schrödinger impact excavated ~20 km into the lunar crust. A Ca-dominated pyroxene and plagioclase (noritic) crustal lithology is exposed in the basin walls, rim, and proximal ejecta. The thickness of the central melt sheet is calculated to be 1.3 to 3.7 km at the crater center, and measured to be <1.2 km, where a 12 km-diameter crater near the periphery of the basin floor penetrates the impact melt and exposes noritic target crust in its ejecta.
In a standard, differentiated-Moon model, the uplifted peak ring of Schrödinger is expected to contain lower crustal norite and upper mantle ultramafics. However, we observe massive blocks of olivine-dominated, pyroxene-free spectra (dunite?), anorthite-dominated spectra with insignificant mafics (anorthosite), and spectra clearly showing olivine + plagioclase (olivine-rich anorthosite or troctolite), which may be a consequence of the earlier SPA impact.
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