Origin and Evolution of the Moon’s Procellarum KREEP Terrane

Bradley Jolliff,Srinidhi Ravi,Mark Robinson

doi:10.3847/25c2cfeb.8668f714

Bradley Jolliff, Srinidhi Ravi + Show 1 more

Open Access

https://doi.org/10.3847/25c2cfeb.8668f714

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Abstract

Whitepaper #294 submitted to the Planetary Science and Astrobiology Decadal Survey 2023-2032. Topics: interior evolution and volcanism; Mercury and/or the Moon; solar system formation, dynamics processes, and chronology

Highlights

The Moon displays a fundamental asymmetry that has been evident since the first images of the farside revealed an ancient, mountainous, heavily cratered feldspathic highlands but very little of the low-lying, dark basaltic plains that are prominent on the nearside, especially the western regions that incorporate Oceanus Procellarum, Imbrium, and several other nearside impact basins
The majority of mare basalts erupted within large impact basins where the low-density upper crust has been substantially thinned
What is the relationship between early planetary differentiation and the volcanic production of a differentiated body? How do planetary-scale asymmetries form and affect the thermal evolution of planets? These are the sorts of questions that can be addressed by further exploration of the Procellarum KREEP Terrane

Summary

Introduction

The Moon displays a fundamental asymmetry that has been evident since the first images of the farside revealed an ancient, mountainous, heavily cratered feldspathic highlands but very little of the low-lying, dark basaltic plains that are prominent on the nearside, especially the western regions that incorporate Oceanus Procellarum, Imbrium, and several other nearside impact basins. A defining characteristic of the Procellarum KREEP Terrane is its unique volcanic history Outside of this terrane, the majority of mare basalts erupted within large impact basins where the low-density upper crust has been substantially thinned. Some of the large impact basins appear to be super-isostatic, that is, the crust-mantle interface has been uplifted above the isostatic level Those basins that formed within or near the boundary of the PKT (Imbrium, Serenitatis, Grimaldi, and Humorum) appear to have been in an isostatic state prior to the emplacement of their mare fill (Wieczorek and Phillips 1999), consistent with enhanced viscous relaxation within the PKT. Owing to the unique character of the PKT, this process was likely confined to this region, but all of the various aspects of these hypotheses need to be proven with on-surface, in-situ analysis

Outstanding questions

Findings

Conclusion