Thicknesses of mare basalts on the Moon from gravity and topography

Gong, Shengxia; Wieczorek, M. A.; Nimmo, F.; Kiefer, W. S.; Head, J. W.; Huang, Chusheng; Smith, David E.; Zuber, M. T.

doi:10.1002/2016je005008

Cited by 54 publications

(74 citation statements)

References 56 publications

(98 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Postimpact mare deposits may also introduce positive RBA (Evans et al, ). We did not find RBA/ D c extremes in Marius Hills, Oceanus Procellarum, where the thickest mare has been suggested (Gong et al, ). This is probably due to the limited spatial coverage of mare craters (Figure a).…”

Section: Resultscontrasting

confidence: 65%

Constraints on Lunar Crustal Porosity From the Gravitational Signature of Impact Craters

et al. 2018

Self Cite

View full text Add to dashboard Cite

Based on Gravity Recovery and Interior Laboratory (GRAIL) observations and the Lunar Orbiter Laser Altimeter (LOLA) crater database, we constrain the spatial variations in the Moon's crustal porosity (ϕc) to a depth of several kilometers using the gravity anomalies of 4,864 midsized craters (those with a diameter of 20–100 km). For each crater, we estimated the local ϕc by quantifying the gravitational effects of impact‐induced porosity change and postimpact breccia infill. The crustal porosity model was uniquely determined assuming a global mean ϕc of 12%, although a trade‐off exists between the porosity of postimpact breccia infill and the (preimpact) crustal porosity that results in zero net porosity change underlying the crater floor. At this crustal porosity the effects of impact bulking and compaction compensate each other to yield zero crater residual Bouguer anomaly (RBA), when the effect of postimpact infill is excluded. For lower crustal porosities, bulking dominates to produce a negative RBA; for higher crustal porosities, compaction dominates to produce a positive RBA. Spatial kriging and statistical tests suggest lower‐than‐average ϕc in the western nearside maria and southern South Pole‐Aitken (SP‐A) basin, in contrast to higher‐than‐average values in the southwestern periphery of the nearside maria. Most of the large impact basins, presumably formed before the majority of the midsized craters we analyzed, show reduced porosities relative to their immediate surroundings.

show abstract

Section: Resultscontrasting

confidence: 65%

Constraints on Lunar Crustal Porosity From the Gravitational Signature of Impact Craters

et al. 2018

Self Cite

View full text Add to dashboard Cite

show abstract

“…However, the inner depression within 195 km of the basin center has been filled with mare up to ~8-9 km in thickness (Solomon and Head, 1980), though later estimates put the mare thickness between 1.5 and 7 km (Gong et al, 2016). The low amplitude of anomalies in the gravity gradients suggests that this basin fill is nearly uniform in density, as might be expected for volcanic fill, and indicates that the density variability seen elsewhere in the crust is not due to late stage (post-mare) generation of porosity variations.…”

Section: Basin Floorsmentioning

confidence: 99%

Small-scale density variations in the lunar crust revealed by GRAIL

Jansen

Andrews-Hanna

et al. 2017

Icarus

View full text Add to dashboard Cite

Data from the Gravity Recovery and Interior Laboratory (GRAIL) mission have revealed that ~98% of the power of the gravity signal of the Moon at high spherical harmonic degrees correlates with the topography. The remaining 2% of the signal, which cannot be explained by topography, contains information about density variations within the crust. These high-degree Bouguer gravity anomalies are likely caused by small-scale (10's of km) shallow density variations. Here we use gravity inversions to model the small-scale three-dimensional https://ntrs.nasa.gov/search.jsp?R=20170003155 2019-06-07T05:41:52+00:00Z 2 variations in the density of the lunar crust. Inversion results from three non-descript areas yield shallow density variations in the range of 100-200 kg/m 3 . Three end-member scenarios of variations in porosity, intrusions into the crust, and variations in bulk crustal composition were tested as possible sources of the density variations. We find that the density anomalies can be caused entirely by changes in porosity. Characteristics of density anomalies in the South PoleAitken basin also support porosity as a primary source of these variations. Mafic intrusions into the crust could explain many, but not all of the anomalies. Additionally, variations in crustal composition revealed by spectral data could only explain a small fraction of the density anomalies. Nevertheless, all three sources of density variations likely contribute. Collectively, results from this study of GRAIL gravity data, combined with other studies of remote sensing data and lunar samples, show that the lunar crust exhibits variations in density by ±10% over scales ranging from centimeters to 100's of kilometers.

show abstract

“…This dome borders the Hortensius and Kepler areas, two areas that were proposed by Spudis et al (2013) as being ancient lunar volcanic shield complexes. The recent study of Gong et al (2016) that uses GRAIL's gravity data to constrain mare thicknesses also situates the thickest pile of mare basalt next to the Marius Hill area.…”

Section: Discussionmentioning

confidence: 98%

“…Regional constraints on mare thicknesses can also be given by studying the gravitational signal recorded above the maria. Lunar maria are, however, often coincident with lunar mascons, and a major difficulty is to extract the signal due to the mare basaltic flows themselves from the signal coming from the processes of impact basin excavation, relaxation and cooling Gong et al, 2016).…”

Section: Introductionmentioning

confidence: 99%