Ultra‐Thick Paleoregolith Layer Detected by Lunar Penetrating Radar: Implication for Fast Regolith Formation Between 3.6 and 2.35 Ga

Abstract

Lunar maria are filled by massive basaltic lava flows layered one over another, suggesting multiple volcanic eruptions (Hiesinger et al., 2003;Sato et al., 2017;Schaber, 1973). Most exposed mare basalt layers dated from ∼3.8 to 3.1 Ga. Some small-scale volcanisms may continue to 1.2 Ga (Hiesinger et al., 2010). In Imbrium basin, the oldest mare basalt dated from an Apollo sample is 3.5 billion years for Imbrium low-titanium basalt (Heiken et al., 1991). Due to subsequent meteoric impact and space weathering between lava flows (about 1 Ga), the paleoregolith layers will be likely formed and then covered by younger Eratosthenian lava flows (high-titanium) (see Figure 1a; Heiken et al., 1991;Wilhelms, 1987). The depth and thickness of the paleoregolith deposits can provide solid constraints on the volume of lava flows and regolith production rate that are directly associated with meteorite flux during this period. The paleoregolith layers have been undisturbed since their formation thus are critical for determining early impacting and volcano history of the Moon and are regarded as important records for uncovering early Moon's history and early solar system history (

From Schrödinger to Von Kármán: An Intriguing New Geological Structure Revealed by the Chang'e‐4 Lunar Penetrating Radar

“…In this layer, the uppermost part probably represents paleo‐regolith just less than two m in thickness; with time, under the effect of impact bombardment, a fine‐grained layer would have developed and subsequently been buried by other materials (Head & Wilson, 2020). The mean regolith production rate at late Imbrian is ∼7.3–20.5 m/Ga (Zhu et al., 2021), hence, it took about 0.1 Ga to form this layer. The lower part is probably ejecta from a large crater/basin.…”

Multidimensional imaging method for measuring microscopic characteristics of geological profile

“…Geological profile measurement is a part of geological exploration engineering measurement. At present, the measurement methods of geological profiles mainly include acoustic emission method [1][2][3] , high-density resistivity method [4][5][6] , geological radar [7][8][9] and other methods, but lack of measurement of the contour of the microscopic surface morphology of geological profiles, and the microscopic measurement method of geological section is mainly the traditional imaging technology which mainly uses the spectral and intensity information of target radiation. The measurement dimension is single, and it is easy to be affected by complex background signals, resulting in the decrease of image contrast [10] .…”