Thermal and Magmatic Evolution of the Moon

Shearer, C. K.

doi:10.2138/rmg.2006.60.4

Cited by 414 publications

(398 citation statements)

References 325 publications

(758 reference statements)

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“…Delano, 1986;Shearer et al, 2006). The picritic volcanic glasses are characterised by a broad range in titanium content, with values ranging up to 16.4 wt%.…”

Section: Introductionmentioning

confidence: 99%

Compressibility of molten Apollo 17 orange glass and implications for density crossovers in the lunar mantle

Parker

Agee

Duncan

et al. 2011

Geochimica et Cosmochimica Acta

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We performed density measurements on a synthetic equivalent of lunar Apollo 17 74,220 "orange glass", containing 9.1 wt% TiO 2 , at superliquidus conditions in the pressure range 0.5-8.5 GPa and temperature range 1723-2223 K using the sink/float technique. In the lunar pressure range, two experiments containing pure forsterite (Fo 100 ) spheres at 1.0 GPa and 1727 K, and at 1.3 GPa-1739 K, showed neutral buoyancies, indicating that the density of molten orange glass was equal to the density of Fo 100 at these conditions (3.09 ± 0.02 g cm À3 ). A third tight sink/float bracket using Fo 90 spheres corresponds to a melt density of 3.25 ± 0.02 g cm À3 at $2.8 GPa and $1838 K.Our data predict a density crossover for the molten orange glass composition with equilibrium orthopyroxene at $2.8 GPa, equivalent to a depth of $600 km in the lunar mantle, and a density of $3.25 g cm À3 . This crossover depth is close to the orange glass multiple saturation point, representing its minimum formation depth, at the appropriate oxygen fugacity (2.8-2.9 GPa). A density crossover with equilibrium olivine is predicted to fall outside the lunar pressure range (>4.7 GPa), indicating that molten orange glass is always less dense than its equilibrium olivines in the Moon. Our data therefore suggest that that lunar liquids with orange glass composition are buoyant with respect to their source region at P < $2.8 GPa, enabling their initial rise to the surface without the need for additional external driving forces.Fitting the density data to a Birch-Murnaghan equation of state at 2173 K leads to an array of acceptable solutions ranging between 16.1 and 20.3 GPa for the isothermal bulk modulus K 2173 and 3.6-8 for its pressure derivative K 0 , with best-fit values K 2173 = 18.8 GPa and K 0 = 4.4 when assuming a model 1 bar density value of 2.86 g cm À3 . When assuming a slightly lower 1 bar density value of 2.84 g cm À3 we find a range for K 2173 of 14.4-18.0 and K 0 3.7-8.7, with best-fit values of 17.2 GPa and 4.5, respectively.

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“…Delano, 1986;Shearer et al, 2006). The picritic volcanic glasses are characterised by a broad range in titanium content, with values ranging up to 16.4 wt%.…”

Section: Introductionmentioning

confidence: 99%

Compressibility of molten Apollo 17 orange glass and implications for density crossovers in the lunar mantle

Parker

Agee

Duncan

et al. 2011

Geochimica et Cosmochimica Acta

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“…The KREEP reservoir (K -potassium, REE -rare earth elements, P -phosphorus, plus other incompatible elements like thorium) is commonly interpreted as a residual liquid resulting from the crystallization of a lunar magma ocean (LMO) that formed soon after accretion of the Moon (e.g., Warren and Wasson, 1979;Warren, 1985Warren, , 1988Jolliff, 1998). One possible interpretation of the global thorium distribution thus suggests that this residual liquid concentrated in an area in the northwest quadrant of the lunar nearside [see discussions by Wieczorek et al (2006) and Shearer et al (2006)]. Later in lunar history, an impactor struck this area at ~3.9 Ga, forming the Imbrium basin and spreading thorium-rich ejecta over a vast portion of the Moon's surface (Haskin, 1998;Haskin et al, 2000;Jolliff et al, 2000;Wieczorek and Phillips, 2000).…”

Section: Introductionmentioning

confidence: 99%

A Rb–Sr and Sm–Nd isotope geochronology and trace element study of lunar meteorite LaPaz Icefield 02205

Rankenburg

Brandon

Norman

2007

Geochimica et Cosmochimica Acta

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“…The subsequent forty years of lunar sample analysis have only supported and strengthened the idea that indigenous water was nearly absent from the Moon's interior. In fact, this conclusion has been incorporated into many petrologic and geophysical models constructed to aid in our understanding of lunar formation and lunar geology (3)(4)(5)(6)(7)(8)(9)(10)(11). The bulk water content of the Moon was recently estimated to be less than 1 ppb (11), which would make the Moon at least six orders of magnitude drier than the interiors of Earth (12,13) and Mars (14).…”

mentioning

confidence: 99%

Nominally hydrous magmatism on the Moon

McCubbin

Steele

Hauri

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

272

185

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For the past 40 years, the Moon has been described as nearly devoid of indigenous water; however, evidence for water both on the lunar surface and within the lunar interior have recently emerged, calling into question this long-standing lunar dogma. In the present study, hydroxyl (as well as fluoride and chloride) was analyzed by secondary ion mass spectrometry in apatite [Ca 5 ðPO 4 Þ 3 ðF,Cl,OHÞ] from three different lunar samples in order to obtain quantitative constraints on the abundance of water in the lunar interior. This work confirms that hundreds to thousands of ppm water (of the structural form hydroxyl) is present in apatite from the Moon. Moreover, two of the studied samples likely had water preserved from magmatic processes, which would qualify the water as being indigenous to the Moon. The presence of hydroxyl in apatite from a number of different types of lunar rocks indicates that water may be ubiquitous within the lunar interior, potentially as early as the time of lunar formation. The water contents analyzed for the lunar apatite indicate minimum water contents of their lunar source region to range from 64 ppb to 5 ppm H 2 O. This lower limit range of water contents is at least two orders of magnitude greater than the previously reported value for the bulk Moon, and the actual source region water contents could be significantly higher. O ne of the scientific discoveries resulting from the Apollo missions was the pervasive waterless nature of the Moon and its rocks. The initial studies of the returned samples were pristine and showed no evidence of aqueous alteration, and water analyses were below detection limits. Moreover, hydrous phases were absent from the lunar rocks aside from a few unconfirmed reports of possible amphibole grains (1), which are now considered by many to represent either misidentifications or terrestrial contamination (as summarized by ref. 2). The subsequent forty years of lunar sample analysis have only supported and strengthened the idea that indigenous water was nearly absent from the Moon's interior. In fact, this conclusion has been incorporated into many petrologic and geophysical models constructed to aid in our understanding of lunar formation and lunar geology (3-11). The bulk water content of the Moon was recently estimated to be less than 1 ppb (11), which would make the Moon at least six orders of magnitude drier than the interiors of Earth (12, 13) and Mars (14). This extremely low water content is in keeping with the pervasive volatile-element depletion signature recorded in all lunar materials, because hydrogen is the most volatile of the elements. The exact cause for this volatile-element depletion is still under question; however, many have argued that it stems from the high temperatures associated with the Moon-forming giant-impact event at ∼4.5 Ga (i.e., refs. 3,8,15,and 16).Facilitated by advancements in analytical detection sensitivities for water, several recent discoveries have indicated that the story of water on the Moon is far from complete. Evi...

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Thermal and Magmatic Evolution of the Moon

Cited by 414 publications

References 325 publications

Compressibility of molten Apollo 17 orange glass and implications for density crossovers in the lunar mantle

Compressibility of molten Apollo 17 orange glass and implications for density crossovers in the lunar mantle

A Rb–Sr and Sm–Nd isotope geochronology and trace element study of lunar meteorite LaPaz Icefield 02205

Nominally hydrous magmatism on the Moon

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