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K H Joy - One of the best experts on this subject based on the ideXlab platform.
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the early geological history of the moon inferred from ancient Lunar Meteorite miller range 13317
2019Co-Authors: N M Curran, Martin J Whitehouse, K H Joy, Joshua F Snape, John F Pernetfisher, J D Gilmour, A A Nemchin, R BurgessAbstract:Abstract Miller Range (MIL) 13317 is a heterogeneous basalt-bearing Lunar regolith breccia that provides insights into the early magmatic history of the Moon. MIL 13317 is formed from a mixture of ...
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mineralogy and petrogenesis of Lunar magnesian granulitic Meteorite northwest africa 5744
2017Co-Authors: Jeremy J Kent, A J Irving, K H Joy, Alan D Brandon, T J Lapen, Anne H Peslier, Daniel M ColeffAbstract:Lunar Meteorite Northwest Africa (NWA) 5744 is a granulitic breccia with an anorthositic troctolite composition that may represent a distinct crustal lithology not previously described. This Meteorite is the namesake and first-discovered stone of its pairing group. Bulk rock major element abundances show the greatest affinity to Mg-suite rocks, yet trace element abundances are more consistent with those of ferroan anorthosites. The relatively low abundances of incompatible trace elements (including K, P, Th, U, and rare earth elements) in NWA 5744 could indicate derivation from a highlands crustal lithology or mixture of lithologies that are distinct from the Procellarum KREEP terrane on the Lunar nearside. Impact-related thermal and shock metamorphism of NWA 5744 was intense enough to recrystallize mafic minerals in the matrix, but not intense enough to chemically equilibrate the constituent minerals. Thus, we infer that NWA 5744 was likely metamorphosed near the Lunar surface, either as a lithic component within an impact melt sheet or from impact-induced shock.
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Assessing the shock state of the Lunar highlands: Implications for the petrogenesis and chronology of crustal anorthosites
2017Co-Authors: Jf Pernet-fisher, K H Joy, Martin Djp, Kl ,donaldson HannaAbstract:Our understanding of the formation and evolution of the primary Lunar crust is based on geochemical systematics from the Lunar ferroan anorthosite (FAN) suite. Recently, much effort has been made to understand this suite's petrologic history to constrain the timing of crystallisation and to interpret FAN chemical diversity. We investigate the shock histories of Lunar anorthosites by combining Optical Microscope (OM) 'cold' cathodoluminescence (CL)-imaging and Fourier Transform Infrared (FTIR) spectroscopy analyses. In the first combined study of its kind, this study demonstrates that over ~4.5 Ga of impact processing, plagioclase is on average weakly shocked (30 GPa; maskelynite) are uncommon. To investigate how plagioclase trace-element systematics are affected by moderate to weak shock (~5 to 30 GPa) we couple REE+Y abundances with FTIR analyses for FAN clasts from Lunar Meteorite Northwest Africa (NWA) 2995. We observe weak correlations between plagioclase shock state and some REE+Y systematics (e.g., La/Y and Sm/Nd ratios). This observation could prove significant to our understanding of how crystallisation ages are evaluated (e.g., plagioclase-whole rock Sm-Nd isochrons) and for what trace-elements can be used to differentiate between Lunar lithologies and assess magma source compositional differences
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Assessing the shock state of the Lunar highlands: Implications for the petrogenesis and chronology of crustal anorthosites
2017Co-Authors: Jf Pernet-fisher, K H Joy, Martin Djp, Kl ,donaldson HannaAbstract:Our understanding of the formation and evolution of the primary Lunar crust is based on geochemical systematics from the Lunar ferroan anorthosite (FAN) suite. Recently, much effort has been made to understand this suite's petrologic history to constrain the timing of crystallisation and to interpret FAN chemical diversity. We investigate the shock histories of Lunar anorthosites by combining Optical Microscope (OM) 'cold' cathodoluminescence (CL)-imaging and Fourier Transform Infrared (FTIR) spectroscopy analyses. In the first combined study of its kind, this study demonstrates that over ~4.5 Ga of impact processing, plagioclase is on average weakly shocked (<15 GPa) and examples of high shock states (>30 GPa; maskelynite) are uncommon. To investigate how plagioclase trace-element systematics are affected by moderate to weak shock (~5 to 30 GPa) we couple REE+Y abundances with FTIR analyses for FAN clasts from Lunar Meteorite Northwest Africa (NWA) 2995. We observe weak correlations between plagioclase shock state and some REE+Y systematics (e.g., La/Y and Sm/Nd ratios). This observation could prove significant to our understanding of how crystallisation ages are evaluated (e.g., plagioclase-whole rock Sm-Nd isochrons) and for what trace-elements can be used to differentiate between Lunar lithologies and assess magma source compositional differences
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an unusual clast in Lunar Meteorite macalpine hills 88105 a unique Lunar sample or projectile debris
2014Co-Authors: K H Joy, I A Crawford, G R Huss, Kazuhide Nagashima, G J TaylorAbstract:Lunar Meteorite MacAlpine Hills (MAC) 88105 is a well-studied feldspathic regolith breccia dominated by rock and mineral fragments from the Lunar highlands. Thin section MAC 88105,159 contains a small rock fragment, 400 × 350 μm in size, which is compositionally anomalous compared with other MAC 88105 lithic components. The clast is composed of olivine and plagioclase with minor pyroxene and interstitial devitrified glass component. It is magnesian, akin to samples in the Lunar High Mg-Suite, and also alkali-rich, akin to samples in the Lunar High Alkali Suite. It could represent a small fragment of late-stage interstitial melt from an Mg-Suite parent lithology. However, olivine and pyroxene in the clast have Fe/Mn ratios and minor element concentrations that are different from known types of Lunar lithologies. As Fe/Mn ratios are notably indicative of planetary origin, the clast could either (1) have a unique Lunar magmatic source, or (2) have a nonLunar origin (i.e., consist of achondritic Meteorite debris that survived delivery to the Lunar surface). Both hypotheses are considered and discussed. © The Meteoritical Society, 2014.
R L Korotev - One of the best experts on this subject based on the ideXlab platform.
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petrology and geochemistry of feldspathic impact melt breccia abar al uj 012 the first Lunar Meteorite from saudi arabia
2016Co-Authors: R L Korotev, Edwin Gnos, Beda A Hofmann, Marianna Meszaros, Pierre Lanari, Nicolas D Greber, Ingo Leya, R C GreenwoodAbstract:Abar al' Uj (AaU) 012 is a clast-rich, vesicular impact-melt (IM) breccia, composed of lithic and mineral clasts set in a very fine-grained and well-crystallized matrix. It is a typical feldspathic Lunar Meteorite, most likely originating from the Lunar farside. Bulk composition (31.0 wt% Al2O3, 3.85wt% FeO) is close to the mean of feldspathic Lunar Meteorites and Apollo FAN-suite rocks. The low concentration of incompatible trace elements (0.39ppmTh, 0.13ppm U) reflects the absence of a significant KREEP component. Plagioclase is highly anorthitic with a mean of An(96.9)Ab(3.0)Or(0.1). Bulk rock Mg# is 63 and molar FeO/MnO is 76. The terrestrial age of the Meteorite is 33.4 +/- 5.2kyr. AaU 012 contains a similar to 1.4x1.5mm(2) exotic clast different from the lithic clast population which is dominated by clasts of anorthosite breccias. Bulk composition and presence of relatively large vesicles indicate that the clast was most probably formed by an impact into a precursor having nonmare igneous origin most likely related to the rare alkali-suite rocks. The IM clast is mainly composed of clinopyroxenes, contains a significant amount of cristobalite (9.0 vol%), and has a microcrystalline mesostasis. Although the clast shows similarities in texture and modal mineral abundances with some Apollo pigeonite basalts, it has lower FeO and higher SiO2 than any mare basalt. It also has higher FeO and lower Al2O3 than rocks from the FAN- or Mg-suite. Its lower Mg# (59) compared to Mg-suite rocks also excludes a relationship with these types of Lunar material.
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ar 40 ar 39 age of an impact melt lithology in Lunar Meteorite dhofar 961
2016Co-Authors: Barbara Cohen, B L Jolliff, R L Korotev, Barbara Frasl, R A ZeiglerAbstract:The Dhofar 961 Lunar Meteorite was found in 2003 in Oman. It is texturally paired with Dhofar 925 and Dhofar 960 (though Dhofar 961 is more mafic and richer in incompatible elements). Several lines of reasoning point to the South Pole-Aitken Basin (SPA) basin as a plausible source (Figure 2): Mafic character of the melt-breccia lithic clasts consistent the interior of SPA, rules out feldspathic highlands. Compositional differences from Apollo impact-melt groups point to a provenance that is separated and perhaps far distant from the Procellarum KREEP Terrane SPA "hot spots" where Th concentrations reach 5 ppm and it has a broad "background" of about 2 ppm, similar to lithic clasts in Dhofar 961 subsamples If true, impact-melt lithologies in this Meteorite may be unaffected by the Imbrium-forming event that is pervasively found in our Apollo sample collection, and instead record the early impact history of the Moon.
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using electron probe microanalysis and quantitative compositional mapping to study lithic clasts in Lunar Meteorites nwa 2727 and nwa 3170
2014Co-Authors: S N Northvalencia, P K Carpenter, B L Jolliff, R L KorotevAbstract:Northwest Africa (NWA) 2727 and NWA 3170, two different stones of the same Lunar Meteorite, are mineralogically and chemically similar [1,2]. Both are breccias that contain an apparently related suite of lithic and mineral clasts. To investigate petrogenetic relationships, we have determined mineral compositional zoning characteristics with Electron Probe Microanalysis (EPMA). The mineralogy includes alkali feldspar (K, Ba, Na), plagioclase, pyroxene (zoned Mg-Fe-Ca), olivine (Fe-rich), and minor amounts of Fe-Ti oxides, phosphates, and troilite. Alteration (Ca-carbonate fracture fillings) occurs in both Meteorites, resulting from hot-desert weathering. In the lithic clasts, mineral-chemical zoning trends, e.g., in pyroxene, are especially useful for comparing lithic clasts and constraining their origins. We used quantitative compositional mapping to study compositional variations, especially for pyroxenes as diagnostic of petrogenetic relationships. We find that quantitative compositional maps extend the characterization of mineral-chemical trends beyond that obtained by EPMA spot analyses.
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the petrogenesis of impact basin melt rocks in Lunar Meteorite shisr 161
2014Co-Authors: A Wittmann, B L Jolliff, R L Korotev, T J Lapen, A J IrvingAbstract:This study explores the petrogenesis of Shisr 161, an immature Lunar regolith breccia Meteorite with low abundances of incompatible elements, a feldspathic affinity, and a significant magnesian component. Our approach was to identify all clasts >0.5 mm in size in a thin section, characterize their mineral and melt components, and reconstruct their bulk major and minor element compositions. Trace element concentrations in representative clasts of different textural and compositional types indicate that the clast inventory of Shisr 161 is dominated by impact melts that include slowly cooled cumulate melt rocks with mafic magnesian mineral assemblages. Minor exotic components are incompatible-element-rich melt spherules and glass fragments, and a gas-associated spheroidal precipitate. Our hypothesis for the petrologic setting of Shisr 161 is that the crystallized melt clasts originate from the upper ~1 km of the melt sheet of a 300 to 500 km diameter Lunar impact basin in the Moon’s feldspathic highlands. This hypothesis is based on size requirements for cumulate impact melts and the incorporation of magnesian components that we interpret to be mantle-derived. The glassy melts likely formed during the excavation of the melt sheet assemblage, by an impact that produced a >15 km diameter crater. The assembly of Shisr 161 occurred in a proximal ejecta deposit of this excavation event. A later impact into this ejecta deposit then launched Shisr 161 from the Moon. Our geochemical modeling of remote sensing data combined with the petrographic and chemical characterization of Shisr 161 reveals a preferred provenance on the Moon’s surface that is close to pre-Nectarian Riemann-Fabry basin.
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comparative zircon u pb geochronology of impact melt breccias from apollo 12 and Lunar Meteorite sau 169 and implications for the age of the imbrium impact
2012Co-Authors: Dunyi Liu, B L Jolliff, R L Korotev, R A Zeigler, Yushan Wan, Hangqiang Xie, Yuhai Zhang, Chunyan Dong, Wei WangAbstract:Abstract The ages of zircons from high-Th impact-melt breccias (IMBs) from Meteorite Sayh al Uhaymir (SaU) 169 and from rock fragments in soil samples from Apollo 12 have been determined using the SHRIMP-II ion microprobe. The IMBs are very similar to each other in chemistry, mineralogy and texture, and the zircons from the KREEP-rich (high-Th) crystalline impact melt have similar U and Th contents and identical ages, within uncertainties, of 3920 ± 13 (2σ) Ma (SaU 169) and 3914 ± 7 (2σ) Ma (Apollo 12). The age results support the idea that the high-Th IMBs (Apollo 12 and SaU 169) formed in the same impact event. The similarity of composition and age suggest that SaU 169 and the high-Th IMB fragments of Apollo 12 originated from the same area of the Procellarum KREEP Terrane. We interpret the age of zircon grains in the Apollo 12 high-Th IMB as a precise and direct determination of the age of the Imbrium impact. This age is significantly older than the commonly cited age of 3.85 Ga but is similar to recent determinations from SIMS U–Pb dating of Apollo 14 apatite grains and with anticipated revision of ages by 40 Ar– 39 Ar and 87 Rb– 86 Sr. The present zircon 207 Pb– 206 Pb age is the first direct zircon age determination of the Imbrium impact event from an Apollo sample. Previous measurements of zircon ages of Apollo IMBs have recorded events pre-dating the Imbrium basin-forming event.
B L Jolliff - One of the best experts on this subject based on the ideXlab platform.
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ar 40 ar 39 age of an impact melt lithology in Lunar Meteorite dhofar 961
2016Co-Authors: Barbara Cohen, B L Jolliff, R L Korotev, Barbara Frasl, R A ZeiglerAbstract:The Dhofar 961 Lunar Meteorite was found in 2003 in Oman. It is texturally paired with Dhofar 925 and Dhofar 960 (though Dhofar 961 is more mafic and richer in incompatible elements). Several lines of reasoning point to the South Pole-Aitken Basin (SPA) basin as a plausible source (Figure 2): Mafic character of the melt-breccia lithic clasts consistent the interior of SPA, rules out feldspathic highlands. Compositional differences from Apollo impact-melt groups point to a provenance that is separated and perhaps far distant from the Procellarum KREEP Terrane SPA "hot spots" where Th concentrations reach 5 ppm and it has a broad "background" of about 2 ppm, similar to lithic clasts in Dhofar 961 subsamples If true, impact-melt lithologies in this Meteorite may be unaffected by the Imbrium-forming event that is pervasively found in our Apollo sample collection, and instead record the early impact history of the Moon.
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using electron probe microanalysis and quantitative compositional mapping to study lithic clasts in Lunar Meteorites nwa 2727 and nwa 3170
2014Co-Authors: S N Northvalencia, P K Carpenter, B L Jolliff, R L KorotevAbstract:Northwest Africa (NWA) 2727 and NWA 3170, two different stones of the same Lunar Meteorite, are mineralogically and chemically similar [1,2]. Both are breccias that contain an apparently related suite of lithic and mineral clasts. To investigate petrogenetic relationships, we have determined mineral compositional zoning characteristics with Electron Probe Microanalysis (EPMA). The mineralogy includes alkali feldspar (K, Ba, Na), plagioclase, pyroxene (zoned Mg-Fe-Ca), olivine (Fe-rich), and minor amounts of Fe-Ti oxides, phosphates, and troilite. Alteration (Ca-carbonate fracture fillings) occurs in both Meteorites, resulting from hot-desert weathering. In the lithic clasts, mineral-chemical zoning trends, e.g., in pyroxene, are especially useful for comparing lithic clasts and constraining their origins. We used quantitative compositional mapping to study compositional variations, especially for pyroxenes as diagnostic of petrogenetic relationships. We find that quantitative compositional maps extend the characterization of mineral-chemical trends beyond that obtained by EPMA spot analyses.
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the petrogenesis of impact basin melt rocks in Lunar Meteorite shisr 161
2014Co-Authors: A Wittmann, B L Jolliff, R L Korotev, T J Lapen, A J IrvingAbstract:This study explores the petrogenesis of Shisr 161, an immature Lunar regolith breccia Meteorite with low abundances of incompatible elements, a feldspathic affinity, and a significant magnesian component. Our approach was to identify all clasts >0.5 mm in size in a thin section, characterize their mineral and melt components, and reconstruct their bulk major and minor element compositions. Trace element concentrations in representative clasts of different textural and compositional types indicate that the clast inventory of Shisr 161 is dominated by impact melts that include slowly cooled cumulate melt rocks with mafic magnesian mineral assemblages. Minor exotic components are incompatible-element-rich melt spherules and glass fragments, and a gas-associated spheroidal precipitate. Our hypothesis for the petrologic setting of Shisr 161 is that the crystallized melt clasts originate from the upper ~1 km of the melt sheet of a 300 to 500 km diameter Lunar impact basin in the Moon’s feldspathic highlands. This hypothesis is based on size requirements for cumulate impact melts and the incorporation of magnesian components that we interpret to be mantle-derived. The glassy melts likely formed during the excavation of the melt sheet assemblage, by an impact that produced a >15 km diameter crater. The assembly of Shisr 161 occurred in a proximal ejecta deposit of this excavation event. A later impact into this ejecta deposit then launched Shisr 161 from the Moon. Our geochemical modeling of remote sensing data combined with the petrographic and chemical characterization of Shisr 161 reveals a preferred provenance on the Moon’s surface that is close to pre-Nectarian Riemann-Fabry basin.
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comparative zircon u pb geochronology of impact melt breccias from apollo 12 and Lunar Meteorite sau 169 and implications for the age of the imbrium impact
2012Co-Authors: Dunyi Liu, B L Jolliff, R L Korotev, R A Zeigler, Yushan Wan, Hangqiang Xie, Yuhai Zhang, Chunyan Dong, Wei WangAbstract:Abstract The ages of zircons from high-Th impact-melt breccias (IMBs) from Meteorite Sayh al Uhaymir (SaU) 169 and from rock fragments in soil samples from Apollo 12 have been determined using the SHRIMP-II ion microprobe. The IMBs are very similar to each other in chemistry, mineralogy and texture, and the zircons from the KREEP-rich (high-Th) crystalline impact melt have similar U and Th contents and identical ages, within uncertainties, of 3920 ± 13 (2σ) Ma (SaU 169) and 3914 ± 7 (2σ) Ma (Apollo 12). The age results support the idea that the high-Th IMBs (Apollo 12 and SaU 169) formed in the same impact event. The similarity of composition and age suggest that SaU 169 and the high-Th IMB fragments of Apollo 12 originated from the same area of the Procellarum KREEP Terrane. We interpret the age of zircon grains in the Apollo 12 high-Th IMB as a precise and direct determination of the age of the Imbrium impact. This age is significantly older than the commonly cited age of 3.85 Ga but is similar to recent determinations from SIMS U–Pb dating of Apollo 14 apatite grains and with anticipated revision of ages by 40 Ar– 39 Ar and 87 Rb– 86 Sr. The present zircon 207 Pb– 206 Pb age is the first direct zircon age determination of the Imbrium impact event from an Apollo sample. Previous measurements of zircon ages of Apollo IMBs have recorded events pre-dating the Imbrium basin-forming event.
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trace element analyses in Lunar Meteorite sayh al uhaymir 169
2008Co-Authors: R A Zeigler, P K Carpenter, B L Jolliff, R L KorotevAbstract:We acquired high precision measurements of Ti in zircon, Sr in plagioclase, and Y, REEs (rare earth elements), and Th in phosphates in Sayh al Uhaymir (SaU) 169, a Lunar Meteorite collected in Oman that is exceptionally rich in incompatible elements. SaU 169 is dilithologic, consisting of an impact-melt breccia (IMB) lithology and a regolith-breccia lithology [1]; all analyses were done on the former. Measurements were done at Washington University on a five-spectrometer JEOL 8200 Superprobe using Probe for Windows software.
K M Rockow - One of the best experts on this subject based on the ideXlab platform.
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geochemistry and petrology of Lunar Meteorite queen alexandra range 94281 a mixed mare and highland regolith breccia with special emphasis on very low titanium mafic components
1998Co-Authors: B L Jolliff, R L Korotev, K M RockowAbstract:— Queen Alexandra Range (QUE) 94281, a Lunar Meteorite recently discovered in Antarctica, is a glassy-matrix, clast-rich regolith breccia containing a mixture of mafic, volcanic-glass and gabbroic constituents and a diverse set of highland constituents. In thin section, the clast assemblage is dominated by coarse mineral debris from a shallow intrusive or hypabyssal setting, or from deep within a thick mare flow. Abundant coarse-grained pyroxene clasts have fine-scale exsolution lamellae and compositions similar to pyroxenes of known Lunar very-low-Ti (VLT) basalts and other Lunar Meteorites of basaltic composition. Pyroxene compositions follow Fe-enrichment extending to hedenbergite, which is associated with fayalite and cristobalite, indicating slow cooling. We refer to the protolith of the crystalline VLT component as VLT gabbro. Fragments of pyroclastic glasses that have high Fe and low Ti concentrations, similar to the pyroclastic green glasses known from Apollo samples, are common. Lithic clasts include abundant subrounded, glassy to cryptocrystalline, aluminous (∼17–30 wt% Al2O3) KREEP-poor melt breccias of highland origin and a variety of other feldspathic impactites. On the basis of composition of our subsamples, QUE 94281 consists of ∼54 wt% mafic or “mare” components and 46 wt% feldspathic or “highland” components. The bulk composition of QUE 94281 is similar to that of Yamato (Y) 793274, but QUE 94281 has slightly greater concentrations of some siderophile elements and slightly lower concentrations of those elements contributed mainly by mafic constituents. Differences in siderophile element concentrations are consistent with longer surface exposure of QUE 94281. Minor differences in trace element variations of subsamples of the two Meteorites suggest subtle differences in the composition of their highland constituents. Nonetheless, the overall similarity of compositions supports the possibility that they were ejected from the same source region on the Moon. The crystalline VLT component of QUE 94281 differs from those known from Apollo 17 and Luna 24 VLT lithologies and from that of basaltic breccia Elephant Moraine (EET) 87521. The VLT-gabbro component and the ferroan VLT volcanic glasses in QUE 94281 have compositions that may be petrogenetically related by derivation from a common picritic parent composition, represented by an ultramafic glass found in QUE 94281.
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Lunar Meteorite queen alexandra range 93069 and the iron concentration of the Lunar highlands surface
1996Co-Authors: R L Korotev, B L Jolliff, K M RockowAbstract:RANDY L. KOROTEV*, BRADLEY L. JOLLIFF AND KAYLYNN M. ROCKOW _..y'_ %,: ,-_//Department of Earth and Planetary Sciences and McDonnell Center for the Space Sciences,Washington University, St. Louis, Missouri 63130, USA*Correspondence author's e-mail address: r[k@levee.wustl.edu(Received 1995 December 19, accepted in revised form 1996 August 3)(Submitted as part of a series of papers on Queen Alexandra Range 93069 and other Lunar Meteorites)Abstract--Lunar Meteorite Queen Alexandra Range 93069 is a clast-rich, glassy-matrix regolith breccia offerroan, highly aluminous bulk composition. It is similar in composition to other feldspathic Lunar Meteoritesbut differs in having higher concentrations of siderophile elements and incompatible trace elements. Basedon electron microprobe analyses of the fusion crust, glassy matrix, and clasts, and instrumental neutron acti-vation analysis of breccia fragments, QUE 93069 is dominated by nonmare components of ferroan, noritic-anorthosite bulk composition. Thin section QUE 93069,31 also contains a large, impact-melted, partiallydevitrified clast of magnesian, anorthositic-norite composition. The enrichment in Fe, Sc, and Cr and lowerMg/Fe ratio of Lunar Meteorites Yamato 791197 and Yamato 82192/3 compared to other feldspathic LunarMeteorites can be attributed to a small proportion (5-10%) of Iow-Ti mare basalt. It is likely that the non-mare components of Yamato 82192/3 are similar to and occur in similar abundance to those of Yamato86032, with which it is paired. There is a significant difference between the average FeO concentration ofthe Lunar highlands surface as inferred from the feldspathic Lunar Meteorites (mean: -5.0%; range: 4.3-6.1%) and a recent estimate based on data from the Clementine mission (3.6%).INTRODUCTIONLunar Meteorite QUE 93069, a 21 g stone, was collected in An-tarctica -45 km from the collection site of the paired Lunar mete-orites MAC 88104 and MAC 88105 (hereafter: MAC 88104/5). Wereport here results of chemical analysis and petrographic examina-tion of QUE 93069 and compare those results with previous resultsfor MAC 88104/5 and other Meteorites from the Lunar highlands.We also report new data for Lunar Meteorite Yamato 86032, some ofwhich were presented previously in a figure in Jolliff et al. (1991).Of the Lunar Meteorites recovered so far, about half have highlyfeldspathic compositions (>25% A1203) and are thought to repre-sent several random locations in the Lunar highlands (e.g., Palme etal., 1991; Warren, 1994). Most contain regolith components andthus appear to represent surface and near surface materials. The lowconcentrations of incompatible trace elements (ITE) in the feldspathicLunar Meteorites compared to highland samples collected by theApollo missions have been taken to mean that the feldspathic mete-orites derive from locations on the Moon distant from the Apollolanding sites (e.g., Pieters et al., 1983; Korotev et al., 1983; Warrenand Kallemeyn, 1986; Jolliffetal., 1991; Palme etal., 1991). Thus,their compositions and components have special significance as theytell us about the nature of the Lunar highlands far removed from anduncontaminated by mafic, ITE-rich, impact-melt qiecta from the largenearside basins. Compositional differences among the Meteoritesand between the Meteorites and the Apollo samples provide valuableinformation about regional variations in the lithologies and compo-sition of the Lunar surface. This type of information is particularlyimportant now that global, remotely sensed compositional data fromthe Clementine mission are available, because the feldspathic LunarMeteorites provide a degree of "ground truth" lbr the vast otherwiseunsampled regions of the highlands.In this paper, we examine the causes of some of the compositionaldifferences among the feldspathic Lunar Meteorites, specifically, theeffects of different proportions of ferroan (low Mg/Fe) and magne-sian (high Mg/Fe) nonmarc components and different proportions ofmare-derived components. We also consider the implications of l:econcentrations in the feldspathic Lunar Meteorites for estimates (Luceyet al., 1995) of the average surface Fe concentration determinedfrom Clementine data.SAMPLES STUDIED AND ANALYTICAL PROCEDURESFor QUE 93069, our study is based on bulk chemical analysis of five50-70-rag fragments (primary splits 9, 10, 11, 20, and 21; Fig. I) andpetrographic study of a thin section (93069,31). We broke each of the fivefragments with an agate mortar and pestle and divided all material fromeach fragment into two or three subsplits designated A, B, and C. In total,1I subsplits were prepared, which ranged in mass from 20 to 32 mg; ten ofthese were dominated by one large chip. Results of electron microprobeanalysis (EMPA) of glass and minerals in the thin section and instrumentalneutron activation analysis (INAA) of the subsplits are presented in TablesI-7.For Yamato 86032, we received 0.5 g of material as nine fragmcnlscollectively designated Yamato 86032, I 15. We broke four of the fragmentsinto smaller chips with an agate mortar and pestle. For INAA, we analyzed20 subsplits: 14 dark chips that appeared relatively devoid of large clasts(3-1 I mg each), 5 chips that were dominated by whitish clastic material (2-7 mg each), and a sample of residual fines (11 mg) [br a total of 114 mg InTable 8, column I contains the mass-weighted mean concentrations of theclast-poor chips and the residual fines subsplit; the sample standard devia-tion and minimum and maximum concentrations observed for these 15 sub-splits are listed in columns 5, 6, and 7. Column 2 contains mass-weightedmean concentrations for the five whitish, clast-rich chips, which were allsimilar in composition. We prepared fused beads for major element analysisby I';MPA of seven of the dark, matrix-rich chips analyzed by INAA andthin sections from three of the remaining large unirradiated fragments (A -107 mg, B = 22 mg, and C = 17 rag). The average major-element composi-lion of the fused beads is given in Table 9 along with the compositions of athick glass vein and the glassy breccia matrix taken from thin section A.All analytical procedures were the same as those described in Jolliff etaL (1991), except that for QUE 93069 the samples received a 24 h irradia-lion.RESULTSPetrography of QUE 93069Our petrographic description is based primarily on examinationof thin section QUE 93069,31 and to a lesser extent on examinationby binocular microscope of the chips analyzed by INAA. The rock909
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Lunar Meteorite queen alexandra range 93069 and the iron concentration of the Lunar highlands surface
1996Co-Authors: R L Korotev, B L Jolliff, K M RockowAbstract:Lunar Meteorite Queen Alexandra Range 93069 is a clast-rich, glassy-matrix regolith breccia of ferroan, highly aluminous bulk composition. It is similar in composition to other feldspathic Lunar Meteorites but differs in having higher concentrations of siderophile elements and incompatible trace elements. Based on electron microprobe analyses of the fusion crust, glassy matrix, and clasts, and instrumental neutron activation analysis of breccia fragments, QUE 93069 is dominated by nonmare components of ferroan, noritic- anorthosite bulk composition. Thin section QUE 93069,31 also contains a large, impact-melted, partially devitrified clast of magnesian, anorthositic-norite composition. The enrichment in Fe, Sc, and Cr and lower Mg/Fe ratio of Lunar Meteorites Yamato 791197 and Yamato 82192/3 compared to other feldspathic Lunar Meteorites can be attributed to a small proportion (5-10%) of low-Ti mare basalt. It is likely that the non- mare components of Yamato 82192/3 are similar to and occur in similar abundance to those of Yamato 86032, with which it is paired. There is a significant difference between the average FeO concentration of the Lunar highlands surface as inferred from the feldspathic Lunar Meteorites (mean: approx. 5.0%; range: 4.3-6.1 %) and a recent estimate based on data from the Clementine mission (3.6%).
Paul H Warren - One of the best experts on this subject based on the ideXlab platform.
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porosities of Lunar Meteorites strength porosity and petrologic screening during the Meteorite delivery process
2001Co-Authors: Paul H WarrenAbstract:Porosity has been directly measured for eight Lunar Meteorite breccias and calculated for two more on the basis of literature density measurements. Lunar Meteorite regolith breccias display systematically low porosity in comparison to otherwise analogous Apollo regolith breccias. Among seven meteoritic regolith breccias, porosity ranges from 1 to 11% and averages 7.5 ± (1-σ) 3.2%, whereas for 44 analogous Apollo samples (porosities mostly calculated from literature density data) the average is 25 ± (1-σ) 7%. The origin of this disparity is enigmatic, but the trend probably reflects mainly a bias in favor of strong, compact breccias among fragments that manage to survive the violent process of launch to Lunar escape velocity (2.38 km/s). In addition, compaction during launch may play an important role. The population of Lunar Meteorites is clearly not a random, unmodified sample of lithic materials near the surface of the parent body.
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Lunar Meteorite queen alexandra range 94281 glass compositions and other evidence for launch pairing with yamato 793274
1999Co-Authors: Tomoko Arai, Paul H WarrenAbstract:Abstract— Lunar Meteorite Queen Alexandra Range 94281 is remarkably similar to Yamato 793274. Pairing in the conventional Earth-entry sense is difficult to reconcile with the 2500 km separation between the find locations for these two samples. Nonetheless, both of these regolith breccias are dominated by very-low-Ti (VLT) mare basalt, the pyroxenes of which feature exsolution lamellae on a remarkably coarse scale (typical lamella width = 0.5–1 μm) by mare standards. The pyroxenes also show similar compositional variations (e.g., Fe# vs. Ti# trends, which confirm parentage from VLT mare basalt). Plots using Al2O3 or FeO as a tracer of the highland component indicate indistinguishable internal mare-highland geochemical mixing trends. The same two distinctive glass types dominate the mare glass populations of both breccias. Glass type YQ1 features 0.37–0.63 wt% TiO2, 10–17 wt% MgO, and 9–11 wt% Al2O3. Glass type YQ2 features higher TiO2 (0.99–1.22 wt%), which is inversely correlated with MgO (12.6–13.8 wt%), and nearly constant (8.8 wt%) Al2O3. All of these similarities suggest that Y-793274 and QUE 94281 are a launch pair, which we designate YQ. Most of these similarities also extend to another mare-breccia Meteorite, Elephant Moraine 87521. However, the EET 87521 mare basalt is unusually V-poor (∼88 μg/g), whereas the YQ mare component contains ∼166 μg/g. Queen Alexandra Range 94281 features a variety of textural domains. Discrete patches of dark matrix material appear to represent clods of mature regolith that have been mixed with a coarser, relatively immature material. Interior to a frothy fusion crust are areas of massive glass that probably formed as a splash coating on QUE 94281 when it was still on the Moon. The coarse YQ and EET 87521 pyroxene exsolution features imply relatively slow cooling in either a very shallow sill or an unusually thick (ponded) lava and/or later annealing within a cryptomare. Mare pyroclastic glasses, including the two YQ varieties, are systematically MgO-rich compared to crystalline mare basalts. This disparity may be a consequence of limited survival of graphite—the main fuel for explosive volcanism—during formation of the mare source regions as magma ocean cumulates. Graphite (2.2 g/cm3) survived preferentially in regions that avoided extensive early melting and thus remained MgO-rich. An apparent bimodality in the TiO2 contents of mare volcanics, especially the pyroclastic glasses, also seems a plausible consequence of petrogenesis by remelting of magma ocean cumulates. Cumulates deposited after the magma ocean evolved to ilmenite saturation had vastly higher TiO2 contents than cumulates deposited shortly before. The YQ regolith's subequal proportions of mare and highland matter are consistent with derivation from a terrain close to a mare-highland boundary. However, a similar mixture might also develop through vertical mixing in a cryptomare or a region of thin mare coverage. Thus, unfortunately, the YQ bulk composition is not a very useful clue to the identity of the source crater.
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the macalpine hills Lunar Meteorite and implications of the Lunar Meteorites collectively for the composition and origin of the moon
1991Co-Authors: Paul H Warren, Gregory W KallemeynAbstract:The MAC88104/MAC88105 Meteorite is a Lunar highlands regolith breccia even more anorthositic than previously available samples of highlands regolith. Clasts studied include two unusual pristine rocks. One, a 2.5-mm, slightly granulitic clast rated as probably pristine, contains extraordinarily Fe-rich (Fo40) olivine. The other, a 5-mm clast with clear vestiges of a poikilitic cumulate texture, has silicate compositions that extend the range of the Mg-suite in the direction of the high-mg∗ end of the ferroan-anorthositic suite. The pyroxene of the latter clast is relatively Ca-rich and poorly equilibrated by Lunar cumulate standards, suggesting that it may have formed in an uncommonly shallow intrusion. The four Lunar highlands Meteorites are all regolith breccias (or, in one case, a marginal type between regolith breccia and “ordinary” polymict breccia), and they probably represent three to four separate Lunar source craters. The proportion of regolith breccias is higher among Lunar highlands Meteorites than among rock samples from the classic highlands site, Apollo 16 (~9% regolith breccias). For the majorelement composition of the crust, the highlands Meteorites confirm that the two low-Th central nearside sites, Luna 20, and especially Apollo 16, are approximately representative. The consistently high-Al2O3 composition indicated for the upper crust supports the magmasphere hypothesis. For the trace-element composition of the crust, the highlands Meteorites indicate that the central nearside Apollo and Luna sites are in several respects grossly unrepresentative. Concentrations of siderophile elements are far lower in highlands-meteoritic regolith breccias than in their central nearside counterparts. The high overall siderophile levels and hyperchondritic NiIr and AuIr ratios characteristic of highlands materials from Apollo 16 and Apollo 14 are evidently idiosyncracies of the central nearside. Concentrations of incompatible elements, including K, Th, and U, are far lower in the highlands Meteorites than in regolith samples from the central nearside. This trend implies that certain lower limits on the bulk-Moon content of U (and associated refractory lithophile elements) should be relaxed. Models of Lunar origin implying large enrichments of refractory lithophile elements are not favored by the new constraints from these Meteorites.
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the macalpine hills Lunar Meteorite and implications of the Lunar Meteorites collectively for the composition and origin of the moon
1991Co-Authors: Paul H Warren, Gregory W KallemeynAbstract:The MAC88104/105 Meteorite, a Lunar highlands regolith breccia, is described. The rock and a number of its component clasts are characterized. One of the clasts is considered to be a rare pristine nonmare rock containing extraordinarily Fe-rich (Fo40) olivine; the other has silicate compositions that extend the range of the Mg-suite in the direction of the high-mg* end of the ferroan-anorthositic suite. For the major element composition of the crust, the highlands Meteorites confirm that the two low-Th central nearside sites, Luna 20 and Apollo 16, are approximately representative. The high Al2O3 composition indicated for the upper crusts supports the magmasphere hypothesis. For the trace-element composition of the crust, the highlands Meteorites indicate that the central nearside Apollo and Luna sites are in several respects grossly unrepresentative.
