Spinel-anorthosites on the Moon: Impact melt origins suggested by enthalpy constraints

Treiman, Allan H.; Kulis, Michael J.; Glazner, Allen F.

doi:10.2138/am-2019-6652

Cited by 14 publications

(17 citation statements)

References 99 publications

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“…(2014), and Treiman et al. (2019) demonstrated in the Forsterite‐Anorthosite‐SiO 2 ternary and Forsterite‐Anorthite binary systems that assimilation of anorthositic wall rock by an olivine‐saturated melt could produce melts in the spinel stability field. These melts would have a crystallization sequence of spinel ⇒ spinel + plagioclase ⇒ spinel + melt react to plagioclase + olivine ⇒ plagioclase + olivine ⇒ olivine + melt reacts to plagioclase + low‐Ca pyroxene.…”

Section: Discussionmentioning

confidence: 99%

“…This has been demonstrated to be a favorable process to account for observations of magmatic rocks with high spinel contents (e.g., pink-spinel anorthosites, ALHA 81005), but is it appropriate for these shallow spinel troctolites? Gross and Treiman (2011), and Treiman et al (2019 demonstrated in the Forsterite-Anorthosite-SiO 2 ternary and Forsterite-Anorthite binary systems that assimilation of anorthositic wall rock by an olivine-saturated melt could produce melts in the spinel stability field. These melts would have a crystallization sequence of spinel ⇒ spinel + plagioclase ⇒ spinel + melt react to plagioclase + olivine ⇒ plagioclase + olivine ⇒ olivine + melt reacts to plagioclase + low-Ca pyroxene.…”

Section: Origin Of the Spinel-bearing Magmatic Lithologiesmentioning

confidence: 99%

See 1 more Smart Citation

Multiple Shallow Crustal Origins for Spinel‐Bearing Lithologies on the Moon: A Perspective From the Luna 20 Mission

et al. 2022

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Spinel (predominantly the MgAl 2 O 4 -end member)-bearing crustal lithologies have long been recognized in the Apollo sample collection. However, such lithologies are rather rare and individual samples are small in mass (<1 g). It has been inferred since the early 1970s that these lithologies (e.g., extensively shocked spinel ± cordierite troctolite clasts) were excavated during basin-forming events from the deep lunar crust and/or upper mantle

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Section: Discussionmentioning

confidence: 99%

Section: Origin Of the Spinel-bearing Magmatic Lithologiesmentioning

confidence: 99%

Multiple Shallow Crustal Origins for Spinel‐Bearing Lithologies on the Moon: A Perspective From the Luna 20 Mission

et al. 2022

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“…Treiman et al. () recently indicated that magnesium aluminate spinel on the walls and central peaks of impact craters results from rapid cooling and partial crystallization of superliquidus melts produced in the impacts by enthalpy constraints. Our experiments indicate that spinel (albeit of a more Fe‐rich composition) can also be a product of LMO crystallization if water was present.…”

Section: Discussionmentioning

confidence: 99%

“…Experiments have shown that such Mg-rich spinel likely formed through the interaction between Mg suite parent magma and anorthositic crust (i.e., during processes that occurred after completion of LMO solidification, Prissel et al 2014;Williams et al 2016). Treiman et al (2019) recently indicated that magnesium aluminate spinel on the walls and central peaks of impact craters results from rapid cooling and partial crystallization of superliquidus melts produced in the impacts by enthalpy constraints. Our experiments indicate that spinel (albeit of a more Fe-rich composition) can also be a product of LMO crystallization if water was present.…”

Section: Comparison With a Nominally Dry Moonmentioning

confidence: 99%

Experimental constraints on the solidification of a hydrous lunar magma ocean

Lin

Hui

Xia

et al. 2019

Meteorit & Planetary Scien

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The identification of hydrogen in a range of lunar samples and the similarity of its abundance and isotopic composition with terrestrial values suggest that water could have been present in the Moon since its formation. To quantify the effect of water on early lunar differentiation, we present new analyses of a high-pressure, high-temperature experimental study designed to model the mineralogical and geochemical evolution of the solidification material equivalent to 700 km deep lunar magma oceans first reported in Lin et al. (2017a). We also performed additional experiments to better quantify water contents in the run products. Water contents in the melt phases in hydrous run products spanning a range of crystallization steps were quantified directly using a secondary ion mass spectrometry (SIMS). Results suggest that a significant but constant proportion (68 AE 5%) of the hydrogen originally added to the experiments was lost from the starting material independent of run conditions and run duration. The volume of plagioclase formed during our crystallization experiments can be combined with the measured water contents and the observed crustal thickness on the Moon to provide an updated lunar interior hygrometer. Our data suggest that at least 45-354 ppm H 2 O equivalent was present in the Moon at the time of crust formation. These estimates confirm the inference of Lin et al. (2017a) that the Moon was wet during its magma ocean stage, with corrected absolute water contents now comparable to estimates derived from the water content in a range of lunar samples.

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“…Since the first discovery of spinel-bearing clasts in Apollo samples, scientists have explored their formation, but have not formed an unified opinion (Gross et al, 2014 and references therein). The petrological characteristics and computational results of the isothermal, isobaric phase diagrams of enthalpy versus composition support recrystallization from impact melts (Treiman et al, 2015). Similarly, impact melting has been suggested as the mode of formation of fine-grained, glassy melt breccias in Dho 1528 and GRA 06157 that contain ＜10 -20 μm spinel phenocrysts (Wittmann et al, 2019).…”

Section: Formation Of Spinel-bearing Clasts In Nwa 13191mentioning

confidence: 75%

A possible origin of the lunar spinel-bearing lithologies as told by the meteorite NWA 13191

Xie,

Chen,

Miao

et al. 2024

American Mineralogist

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Pink spinel anorthosite (PSA) and pink spinel troctolite (PST) are two lunar lithologies known to contain Mgrich spinel. PSA rich in spinel and lacking mafic minerals, was detected by the visible and near-infrared reflectance spectroscopy. PST clasts were found in returned lunar samples and meteorites. NWA 13191 is a recently approved lunar meteorite that contains a large amount of spinel-bearing clasts and provides an opportunity to discuss its origin. In this paper, 64 spinel-bearing clasts are studied. These clasts are dominated by anorthitic feldspars (20.8 -80.9 vol.%, An90.9-96.8), mafic-rich and aluminum-rich melt (14.7 -72.1 vol.%) and spinels (0.19 -5.18 vol.%). 49 of these clasts appears to have an unusually low modal abundance of mafic silicates (avg. olivine ± pyroxene, 1.87 vol.%), which distinguishes it from known spinel-bearing lunar samples (e.g., PST). The spinel composition (avg. Mg # = 90.6, Al # = 97.4) and mafic minerals content are basically consistent with those of PSA. The absorption characteristics of the melt in the reflection spectrum are not obvious, so it is not clear if the PSA contains melt. The simulated crystallization experiment clearly shows that it contains a large amount of melt at the spinel crystallization stage. These phenomena provide experimental and sample evidences for the existence of melt in the lunar spinel-bearing lithologies. NWA 13191 records the highest known bulk Mg # (avg. 89.8) and the spinel records the highest Al # (98.8) and Mg # (93.1) of lunar samples to date. The chemical properties of spinel-bearing clasts in NWA 13191 are consistent with the slightly REE-enriched and alkali-poor Mg-suite rocks, such as PST, magnesian anorthosites (MANs), and olivine-enriched Mg-suite rocks. These phenomena and previous simulated crystallization experiments indicate that the Mg-Al-rich melt may be produced by impact melting of Mg-rich anorthosite precursors. The spinel is a metastable crystallization product along with plagioclase and vitric melt near the Moon's surface. This realization provides sample observational evidence for previous simulated crystallization experiments and theoretical speculations.

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Spinel-anorthosites on the Moon: Impact melt origins suggested by enthalpy constraints

Cited by 14 publications

References 99 publications

Multiple Shallow Crustal Origins for Spinel‐Bearing Lithologies on the Moon: A Perspective From the Luna 20 Mission

Multiple Shallow Crustal Origins for Spinel‐Bearing Lithologies on the Moon: A Perspective From the Luna 20 Mission

Experimental constraints on the solidification of a hydrous lunar magma ocean

A possible origin of the lunar spinel-bearing lithologies as told by the meteorite NWA 13191

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