Investigating the Influences of Crustal Thickness and Temperature on the Uplift of Mantle Materials Beneath Large Impact Craters on the Moon. Issue 2 (18th February 2021)

• Record Type: Journal Article
• Authors: Ding, Min; Soderblom, Jason M.; Bierson, Carver J.; Zuber, Maria T.
• Is Part Of: Journal of geophysical research. Volume 126:Issue 2(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-02-18
• Subjects: Crustal thickness -- gravity -- impact crater -- mantle uplift -- Moon -- temperature; Planets -- Periodicals; Geophysics -- Periodicals; 559.9
• DOI: 10.1029/2020JE006533
• Languages: English
• ISSNs: 2169-9097

Abstract

Abstract: In this work, we examine variations in the mantle uplift associated with large lunar impact craters and basins between major terranes. This study is based on Bouguer gravity anomalies of 100–650‐km diameter impact craters using Gravity Recovery and Interior Laboratory (GRAIL) observations and the Lunar Orbiter Laser Altimeter (LOLA) crater database. The Bouguer gravity anomalies of 324 large impact craters analyzed herein are primarily controlled by the uplifted crust‐mantle (Moho) interface in the central region of these impact craters, while postimpact mare deposits that represent ∼25%–35% of the postimpact deposit column also contribute to the gravity anomalies of mare craters. The central uplift of the Moho interface is primarily controlled by impact energy and increases to ∼ 30 km for a 650‐km diameter crater. Analyses of nonmare craters in the Feldspathic Highlands Terrane (FHT) with varied crustal thickness ( T c ) reveal that the onset crater diameter ( D min ) with an uplifted Moho interface is dependent on the local T c : D min ∼ 150 + 1.3 T c (in a unit of km). This equation also provides a quantification of the depth‐dependent attenuation of impact‐induced structural uplift, using the Moho uplift as a proxy for the structural uplift. The Moho uplift of large craters in the South Pole‐Aitken (SPA) Terrane is not statistically different from the FHT craters, consistent with limited overall thermal difference between these two terranes and compensational thermal effects at crater collapse and viscoelastic relaxation stages. Plain Language Summary: Gravitational signatures of impact basins reveal notable mantle uplifts under the basin floor. The mantle uplift is significant for lunar basins with a crater diameter larger than ∼ 200 km and is one of the main characteristics for peak‐ring and multiring basins. The magnitude of the mantle uplift increases with impact energy, which also correlates with crater diameter. It has been suggested that the target properties, including the crustal thickness and thermal state, affect the crater mantle uplift as well. In this study, we find that increasing crustal thickness reduces basin mantle uplift. But there is no statistical difference between the mantle uplifts of impact basins formed in the highlands and those in the South Pole‐Aitken basin. We attribute this to limited thermal differences between the two terranes in the pre‐Nectarian period, which is consistent with the hypothesized early lunar thermal evolution and impact chronology. The compensational thermal effects at the transient crater collapse and viscoelastic relaxation stages also help explain this statistical indistinguishability. Key Points: The minimum crater diameter for which impacts result in mantle uplift is positively correlated with local crustal thickness Gravity signatures of mare craters suggest that the mare deposits account for ∼ 25%–35% of the thickness of postimpact deposits Statistical indistinguishability between the SPA and FHT craters provides an upper limit on the effect of thermal difference