On the origin of the lunar smooth-plains

Oberbeck, V. R.; Hörz, Friedrich; Morrison, R. H.; Quaide, W. L.; Gault, D. E.

doi:10.1007/bf02626332

Cited by 96 publications

(100 citation statements)

References 18 publications

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“…1a and 1b. Oberbeck et al (1975) we have quantified the amount of material ejected by basins across the lunar surface and mapped the predicted depth of the well-mixed megaregolith. This quantification of the effects of basin formation on the lunar crust allows us to discuss the relationship between basin formation and several key aspects of lunar geology: 1) the relationship between the global distribution of basin ejecta and the depth to which it is mixed in the context of lunar geochemical terranes identified by Jolliff et al (2000), 2) the context of the Apollo and Luna landing sites with respect to the effects of basin formation, and 3) the potential relationship between the lunar seismic structure and the depth of the megaregolith.…”

Section: Discussionmentioning

confidence: 99%

“…The mixing ratio utilized in the megaregolith model is modified from the original Oberbeck et al (1975) (5) where R s is the range from the center of the crater to the location of interest. The equation for the modified mixing ratio value as used by Petro and Pieters (2006), which has been referred to as "µ/2" is given by the equation…”

Section: Discussionmentioning

confidence: 99%

“…Petro and Pieters (2004) presented a model to quantify the effects of basin formation and estimate the resulting proportion of locally derived material relative to foreign material in the regolith. Petro and Pieters utilized the ejecta scaling equations of Pike (1974) and Housen et al (1983) and the concept of an ejecta mixing ratio from Oberbeck et al (1975). Although similar in concept to the detailed model of Haskin et al (2003aHaskin et al ( , 2003b, the Petro and Pieters approach readily allows global scale issues to be addressed.…”

Section: Basin Ejecta Modelingmentioning

confidence: 99%

“…The Mean* TC diameter values are from Petro and Pieters (2004) and Wieczorek and Phillips (1999 aspects of basin modification of the surface: 1) the amount of basin ejecta distributed across the surface and 2) the mixing that occurs when the ejected material is ballistically emplaced onto the surface. The re-impact of ejecta into the lunar surface creates a mixed zone that contains some proportion of both distally and locally derived material (Oberbeck et al 1975;Schultz and Gault 1985). Here we will model both the depth of this mixed zone as well as the cumulative amount of material laterally transported by basin impact processes for the entire lunar surface.…”

Section: Early Models Of Crater Modification Of the Lunar Surfacementioning

confidence: 99%

“…At all points on the grid there are 42 independent values of the amount of ejecta for each basin. Additionally, a modified (lower) value of the mixing ratio of Oberbeck et al (1975) is used at all points for each basin (see the appendix for details). These values were used to describe the total amount of basin ejecta redistributed around the Moon and the depth to which that material mixed for each event.…”

Section: Lunar-wide Distribution Of Cumulative Ejected Materials From mentioning

confidence: 99%

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The lunar‐wide effects of basin ejecta distribution on the early megaregolith

Petro

Pieters

2008

Meteorit & Planetary Scien

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Abstract-The lunar surface is marked by at least 43 large and ancient impact basins, each of which ejected a large amount of material that modified the areas surrounding each basin. We present an analysis of the effects of basin formation on the entire lunar surface using a previously defined basin ejecta model. Our modeling includes several simplifying assumptions in order to quantify two aspects of basin formation across the entire lunar surface: 1) the cumulative amount of material distributed across the surface, and 2) the depth to which that basin material created a well-mixed megaregolith. We find that the asymmetric distribution of large basins across the Moon creates a considerable nearside-farside dichotomy in both the cumulative amount of basin ejecta and the depth of the megaregolith. Basins significantly modified a large portion of the nearside while the farside experienced relatively small degrees of basin modification following the formation of the large South Pole-Aitken basin. The regions of the Moon with differing degrees of modification by basins correspond to regions thought to contain geochemical signatures remnant of early lunar crustal processes, indicating that the degree of basin modification of the surface directly influenced the distribution of the geochemical terranes observed today. Additionally, the modification of the lunar surface by basins suggests that the provenance of lunar highland samples currently in research collections is not representative of the entire lunar crust. Identifying locations on the lunar surface with unique modification histories will aid in selecting locations for future sample collection.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Basin Ejecta Modelingmentioning

confidence: 99%

Section: Early Models Of Crater Modification Of the Lunar Surfacementioning

confidence: 99%

Section: Lunar-wide Distribution Of Cumulative Ejected Materials From mentioning

confidence: 99%

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The lunar‐wide effects of basin ejecta distribution on the early megaregolith

Petro

Pieters

2008

Meteorit & Planetary Scien

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Characterization of space weathering from Lunar Reconnaissance Orbiter Camera ultraviolet observations of the Moon

Denevi

Robinson

Boyd

et al. 2014

J. Geophys. Res. Planets

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We investigate the effects of space weathering at ultraviolet wavelengths using a near-global seven-band (321-689 nm) mosaic from the Lunar Reconnaissance Orbiter Camera (LROC) Wide Angle Camera (WAC). We confirm that for moderate-to high-iron compositions (≳ 5 wt % FeO), the steeply positive UV slope at wavelengths <415 nm shallows with increasing exposure to space weathering. We measure these differences in LROC WAC data as variations in the 321/415 nm ratio, which has low values for fresh craters in the mare and moderate-iron highlands. For low-iron highland compositions, the break in slope occurs at shorter wavelengths, and it is instead the 321/360 nm ratio that increases with exposure to the space-weathering environment, whereas the 321/415 nm ratio appears to be largely controlled by the degree of shock experienced during the impact. The effects of shock may be more important at highland craters because modest shock pressures result in the solid-state transformation of plagioclase to its glass equivalent, maskelynite, and can help distinguish between primary shocked ejecta and locally exposed fresh material in rays. While all of the "fresh" craters we examined have UV spectral properties consistent with substantial alteration due to space weathering, the UV spectra of lunar swirls (magnetically shielded from the solar wind) are consistent with exposure of immature, crystalline material. Together these results suggest that lunar space weathering is dominated by the solar wind and "saturates" in the UV at I s /FeO values of 40 (submature).

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Lunar Volcanism in Space and Time

Head¹

1977

1977, Reviews of Lunar Sciences

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On the origin of the lunar smooth-plains

Cited by 96 publications

References 18 publications

The lunar‐wide effects of basin ejecta distribution on the early megaregolith

The lunar‐wide effects of basin ejecta distribution on the early megaregolith

Characterization of space weathering from Lunar Reconnaissance Orbiter Camera ultraviolet observations of the Moon

Lunar Volcanism in Space and Time

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