New observational evidence of global seismic effects of basin‐forming impacts on the Moon from Lunar Reconnaissance Orbiter Lunar Orbiter Laser Altimeter data

Abstract

[1] New maps of kilometer-scale topographic roughness and concavity of the Moon reveal a very distinctive roughness signature of the proximal ejecta deposits of the Orientale basin (the Hevelius Formation). No other lunar impact basin, even the just-preceding Imbrium basin, is characterized by this type of signature although most have similar types of ejecta units and secondary crater structures. The preservation of this distinctive signature, and its lack in basins formed prior to Orientale, is interpreted to be the result of seismically induced smoothing caused by this latest major basin-forming event. Intense seismic waves accompanying the Orientale basin-forming event preceded the emplacement of its ejecta in time and operated to shake and smooth steep and rough topography associated with earlier basin deposits such as Imbrium. Orientale ejecta emplaced immediately following the passage of the seismic waves formed the distinctive roughness signature that has been preserved for almost 4 billion years.

The Miniature Radio Frequency instrument’s (Mini-RF) global observations of Earth’s Moon

“…Interestingly, recent LOLA roughness studies by Kreslavsky and Head [2012] and Rosenburg et al [2011] reported low concavity values that suggest not just western Orientale, but the entire basin and ejecta of the Hevelius formation have uniquely high kilometer-scale roughness characteristics. This is not contradictory to radar findings but reflective of how roughness and the size of material scatterers vary when measured at multiple wavelength scales.…”

“…Mini-RF, Diviner, LROC, and LOLA-derived data products [e.g., Bandfield et al, 2011;Rosenburg et al, 2011;Kreslavsky and Head, 2012;Scholten et al, 2012] enable a crosssectional view of depths similar to or greater for physical parameter characteristics of these same surfaces that were analyzed with Clementine and Lunar Prospector data.…”

Lunar cryptomaria: Physical characteristics, distribution, and implications for ancient volcanism

“…LOLA-derived surface roughness data were converted to a roughness parameter (Kreslavsky and Head, 2012;Kreslavsky et al, 2013); three separate length scales were used to parameterize surface roughness, 0.115 km, 0.46 km, 1.84 km. Lower values of the roughness parameter indicate smoother deposits.…”

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

“…Seismic shaking from subsequent impacts appears to have a substantial effect on both the roughness (Kreslavsky and Head, 2012) and density of these older basin ejecta deposits.…”