Cratering History and Lunar Chronology

Stöffler, D.; Ryder, G.; Ivanov, B. A.; Artemieva, N. A.; Cintala, M. J.; Grieve, R. A. F.

doi:10.2138/rmg.2006.60.05

Cited by 318 publications

(294 citation statements)

References 236 publications

(346 reference statements)

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“…In the case of sample 79215, peak metamorphism is dated at 3.9 Ga, which may correlate with formation of the Serenitatis impact basin (Stöffler et al, 2006). The other three samples indicate peak metamorphic ages of ~4.1 Ga.…”

Section: Discussionmentioning

confidence: 86%

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A laser probe 40Ar/39Ar and INAA investigation of four Apollo granulitic breccias

Hudgins

Spray

Kelley

et al. 2008

Geochimica et Cosmochimica Acta

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Infrared laser probe 40 Ar/ 39 Ar geochronology, instrumental neutron activation analysis (INAA) and analytical electron microscopy have been performed on four 0.5 x 1.0 x 0.3 cm polished rock tiles of Apollo 16 and 17 granulitic breccias (60035, 77017, 78155, and 79215). Pyroxene thermometry indicates that these samples were re-equilibrated and underwent peak metamorphic sub-solidus recrystallization at 1000 -1100˚C, which resulted in homogeneous mineral compositions and granoblastic textures. 40 Ar/ 39 Ar data from this study reveal that three samples (60035, 77017, and 78155) have peak metamorphic ages of ~4.1 Ga. Sample 79215 has a peak metamorphic age of 3.9 Ga, which may be related to Serenitatis basin formation. All four samples contain moderately high concentrations of meteoritic siderophiles. Enhanced siderophile contents in three of the samples provide evidence for projectile contamination of their target lithologies occurring prior to peak metamorphism.Post-peak metamorphism, low-temperature (<300ºC) events caused the partial resetting of argon in the two finer-grained granulites (60035 and 77017). These later events did not alter the mineralogy or texture of the rocks, but caused minor brecciation and the partial release of argon from plagioclase.Interpretation of the low-temperature data indicates partial resetting of the argon systematics to as young as 3.2 Ga for 60035 and 2.3 Ga for 77017. Cosmic ray exposure ages range from 6.4 to ~339 Ma.Our results increase the amount of high-precision data available for the granulitic breccias and lunar highlands crustal samples. The results demonstrate the survival of pre-Nectarian material on the lunar surface and document the effects of contact metamorphic and impact processes during the pre-Nectarian Epoch, as well as the low-temperature partial resetting of ages by smaller impact events after 3.9 Ga. ACCEPTED MANUSCRIPTThe mineralogy and chemical composition of these rocks, as well as exhumation constraints, indicate that the source of heat for metamorphism was within kilometres of the surface via burial beneath impact melt sheets or hot ejecta blankets. INTRODUCTIONLunar granulitic breccias comprise a suite of metamorphic rocks recovered at most Apollo and Luna landing sites and found within non-mare lunar meteorites (e.g., ALHA 81005, SaU 300, NWA 3163/4481/4483). They typically occur as lithic clasts in breccias, but some monolithic rocks have been sampled (e.g., 78155 and 79215). Those occurring as lithic clasts have been incorporated into polymict impact-melt breccias.Their diagnostic feature is a granoblastic to poikiloblastic matrix texture attributed to heating to ~1000 ˚C, which resulted in subsolidus recrystallization. There is no evidence of plastic deformation and, in this respect, the rocks can be likened to high-temperature terrestrial hornfelses. The source of heat for metamorphism has been debated. Two scenarios appear feasible: 1) heating of the rock due to burial at depth within the lunar crust (deep origin), and 2) juxtaposit...

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Section: Discussionmentioning

confidence: 86%

“…In the case of sample 79215, peak metamorphism is dated at 3.9 Ga, which may correlate with formation of the Serenitatis impact basin (Stöffler et al, 2006). versus An (molar Ca/(Ca+Na+K) x 100) in feldspar for minerals present in the lithic clasts observed in the four studied granulitic breccias.…”

Section: Discussionmentioning

confidence: 88%

A laser probe 40Ar/39Ar and INAA investigation of four Apollo granulitic breccias

Hudgins

Spray

Kelley

et al. 2008

Geochimica et Cosmochimica Acta

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“…The primary lunar crust is dominated by ferroan anorthosites (Smith et al, 1970;Wood et al, 1970), while extrusive KREEP basalts and intrusive Mg-suite rocks are derived from melts of the lunar mantle (Warren and Wasson, 1977). The few dated samples of Mg-suite rocks and KREEP basalts indicate ancient ages 43.8 Ga, immediately after the Imbrium formation event (Nyquist et al, 1975;Papanastassiou and Wasserburg, 1976;Ryder and Spudis, 1980;Nyquist and Shih, 1992;Stöffler et al, 2006). There is no indication that these lithologies continued to be produced after 3.8 Ga.…”

Section: Introductionmentioning

confidence: 99%

“…Returned samples tell the story of a much more compositionally and temporally diverse volcanic history compared to the mare basalt deposits. During the first $ 500 My, the Moon was simultaneously producing mare basalts, KREEP basalts, and Mg-suite rocks (Ryder and Spudis, 1980;Taylor et al, 1983;Nyquist and Shih, 1992;Stöffler et al, 2006;Terada et al, 2007). Soon afterwards, around 3.8 Ga, there was either a substantial increase in the eruption of mare basalts or a decrease in the production of parental melts for KREEP basalts and Mg-suite rocks, or both processes occurred simultaneously.…”

Section: Introductionmentioning

confidence: 99%

Lunar cryptomaria: Mineralogy and composition of ancient volcanic deposits

Whitten

Head

2015

Planetary and Space Science

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“…Based on radiometric 15 ages of impact melts of lunar samples, the concept of a short, intense period of impacts on the Moon at ∼3.9 Ga was proposed (e.g., Tera et al, 1974;Cohen et al, 2000). This heavy bombardment on the Moon is often called the lunar cataclysm or the Late Heavy Bombardment (LHB) and has been debated for decades since it is related to the bombardment on the early Earth and the 20 dynamical evolution of the Solar System (e.g., Stöffler et al, 2006;Gomes et al, 2005). One end-member is an intensive LHB model which assumes that most impact basins, including degraded ones, were formed during this short period (e.g., Ryder, 2002).…”

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confidence: 99%

The relative timing of Lunar Magma Ocean solidification and the Late Heavy Bombardment inferred from highly degraded impact basin structures

Kamata

Sugita

Abe

et al. 2015

Icarus

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The solidification of the Lunar Magma Ocean (LMO) and formation of impact basins are important events that took place on the early Moon. The relative timing of these events, however, is poorly constrained. The aim of this study is ing substantial viscous lateral flow in the crust. Recent geodetic measurements reveal that the lunar crust is thinner than previously estimated, indicating that an extremely high crustal temperature is required for lateral flow to occur. In this study, we calculate lunar thermal evolution and viscoelastic deformation of basins and investigate the thermal state at the time of basin formation using recent crustal thickness models. We find that a Moho temperature >1300-1400K at the time of basin formation is required for substantial viscous relaxation of topography to occur; the implied elastic thickness at the time of loading is <30 km. Such a high temperature can be maintained only for a short time (i.e., <50Myr for most conditions) after solidification of the LMO or after mantle overturn if it took place; relaxed impact basins forming ≥150 Myr later than LMO solidification are unlikely. This result is in conflict with an intensive Late Heavy Bombardment (LHB) model, which assumes that most impact basins were formed at ∼3.9 Ga, since it requires LMO solidification time extremely later than previous theoretical estimates. Either the LHB was moderate, or the majority of proposed early PN basins were not in fact formed by impacts.

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Cratering History and Lunar Chronology

Cited by 318 publications

References 236 publications

A laser probe 40Ar/39Ar and INAA investigation of four Apollo granulitic breccias

A laser probe 40Ar/39Ar and INAA investigation of four Apollo granulitic breccias

Lunar cryptomaria: Mineralogy and composition of ancient volcanic deposits

The relative timing of Lunar Magma Ocean solidification and the Late Heavy Bombardment inferred from highly degraded impact basin structures

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