The Tatahouine diogenite: Mineralogical and chemical effects of sixty‐three years of terrestrial residence

Barrat, Jean‐Alix; Gillet, Ph.; Lesourd, M.; Blichert‐Toft, Janne; Poupeau, Gérard

doi:10.1111/j.1945-5100.1999.tb01734.x

Cited by 89 publications

(101 citation statements)

References 33 publications

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“…They are found on all types of substrates at the surface of the meteorite (calcite, orthopyroxene, or chromite). Moreover, the same rodshaped forms are found on several other objects collected in the Tataouine sand (21).…”

mentioning

confidence: 72%

“…Vecht and Ireland (36) propose that rod-shaped features in calcites observed in ALH84001 (6) and in the Tataouine diogenite (21) could result from the pseudomorphic replacement of vaterite by calcite. Indeed, they synthesized small spherical vaterite particles ranging between 50 and 100 nm in diameter, similar in shape and size to many of the nanobacteria-like objects reported in these studies.…”

Section: Discussion Relationships Between Calcite Precipitates and Pymentioning

confidence: 99%

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Nanobacteria-like calcite single crystals at the surface of the Tataouine meteorite

Benzerara

Menguy

Guyot

et al. 2003

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

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Nanobacteria-like objects evidenced at the surface of the orthopyroxenes of the Tataouine meteorite in South Tunisia have been studied by scanning and transmission electron microscopies. A method of micromanipulation has been developed to ensure that exactly the same objects were studied by both methods. We have shown that the nanobacteria-like objects are spatially correlated with filaments of microorganisms that colonized the surface of the meteoritic pyroxene during its 70 years of residence in the aridic Tataouine soil. Depressions of a few micrometers in depth are observed in the pyroxene below the carbonates, indicating preferential dissolution of the pyroxene and calcite precipitation at these locations. The nanobacteria-like small rods that constitute calcium carbonate rosettes are well crystallized calcite single crystals surrounded by a thin amorphous layer of carbonate composition that smoothes the crystal edges and induces rounded shapes. Those morphologies are unusual for calcite single crystals observed in natural samples. A survey of recent literature suggests that the intervention of organic compounds derived from biological activity is likely in their formation.

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mentioning

confidence: 72%

Section: Discussion Relationships Between Calcite Precipitates and Pymentioning

confidence: 99%

Nanobacteria-like calcite single crystals at the surface of the Tataouine meteorite

Benzerara

Menguy

Guyot

et al. 2003

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

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“…If the melt has been almost totally expelled, as is the case for the diogenites (e.g., Barrat 2004), zoning can be far less pronounced, or the volume of rim material highly restricted compared to that of the core. In other words, the average composition of the crystals may not necessarily be far removed from that of their core and Berkley and Boynton (1992), Mittlefehldt (1994Mittlefehldt ( , 2000, Fowler et al (1994Fowler et al ( , 1995, Domanik et al (2003), Liermann and Ganguly (2001), Barrat et al (1999Barrat et al ( , 2006 and this study. The 2σ errors for the new analyses are equivalent to the size of the data points.…”

Section: How Many Parental Melts For Diogenites?mentioning

confidence: 90%

“…A similar explanation has been proposed by Mittlefehldt (2000) for Elephant Moraine (EET) A79002. Clearly, if this nugget effect is correct, it will need to be taken into account, not only for the interpretation of highly siderophile element abundances in bulk rocks, but also in dating studies using those produced during hot desert weathering (e.g., Barrat et al 1999Barrat et al , 2006, accessory phases (e.g., phosphates, plagioclase), a trapped melt fraction, or any foreign fragments (e.g., chondritic meteorites, plagioclase or small eucritic clasts in diogenitic breccias, see Lomena et al [1976], Hewins [1988] and Mittlefehldt [1994]). Therefore, the abundances of light REEs in orthopyroxene compared to bulk rocks can differ significantly.…”

Section: Factors Controlling the Composition Of Diogenitesmentioning

confidence: 99%

Geochemistry of diogenites: Still more diversity in their parental melts

Barrat

Yamaguchi

Greenwood

et al. 2008

Meteorit & Planetary Scien

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154

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Abstract-We report on the major and trace element abundances of 18 diogenites, and O-isotopes for 3 of them. Our analyses extend significantly the diogenite compositional range, both in respect of Mg-rich (e.g., Meteorite Hills [MET] 00425, MgO = 31.5 wt%) and Mg-poor varieties (e.g., Dhofar 700, MgO = 23 wt%). The wide ranges of siderophile and chalcophile element abundances are well explained by the presence of inhomogeneously distributed sulfide or metal grains within the analyzed chips. The behavior of incompatible elements in diogenites is more complex, as exemplified by the diversity of their REE patterns. Apart from a few diogenite samples that contain minute amounts of phosphate, and whose incompatible element abundances are unlike the orthopyroxene ones, the range of incompatible element abundances, and particularly the range of Dy/Yb ratios in diogenites is best explained by the diversity of their parental melts. We estimate that the FeO/MgO ratios of the diogenite parental melts range from about 1.4 to 3.5 and therefore largely overlap the values obtained for non-cumulate eucrites. Our results rule out the often accepted view that all the diogenites formed from parental melts more primitive than eucrites during the crystallization of a magma ocean. Instead, they point to a more complex history, and suggest that diogenites were derived from liquids produced by the remelting of cumulates formed from the magma ocean.

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“…;:c to r;; Barrat et al (1999). EET 84302, Gibson, LEW 88280, Fukuoka and Kimura (1990); Torigoye et al (1993); Lodran (silicate), MAC 88177, Mittlefehldt et at (1996);Weigel et al (1999).…”

Section: Imartimentioning

confidence: 99%

The trapped noble gas component in achondrites

Busemann

Eugster

2002

Meteorit & Planetary Scien

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Abstract-The trapped noble gases Ar, Kr and Xe in several achondrites were analysed. We chose separates of the lodranites Lodran and Graves Nunataks 95209 and bulk samples ofthe Tatahouine diogenite, Pasamonte eucrite, five aubrites and two angrites. Among these, Lodran, Tatahouine, Pasamonte and the aubrite Norton County have been reported to contain U-Xe, a noble gas component assumed to be the most primitive component in the solar system. U-Xe might have been incorporated into the early Earth. We found large concentrations ofXe in several separates of the Lodran lodranite, however, none of the measurements revealed U-Xe composition. The Xe composition of all achondrites can straightforwardly be explained with mixtures of trapped common Xe-Q, absorbed air and various amounts offissiogenic and cosmogenic Xe. Reanalysis ofliterature data for Pasamonte, Angra dos Reis and some aubrites is consistent with Xe-Q as the trapped endmember component and contributions offissiogenic Xe. The presence ofXe-Q in many primitive achondrites is in agreement with the formation of their parent bodies from originally chondritic precursor material. The Ar-Xe elemental composition of Lodran and the aubrites indicate subsolar composition, which is commonly found in E chondrites. This result supports a model of formation of the aubrites from E-chondritic precursor material.

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The Tatahouine diogenite: Mineralogical and chemical effects of sixty‐three years of terrestrial residence

Cited by 89 publications

References 33 publications

Nanobacteria-like calcite single crystals at the surface of the Tataouine meteorite

Nanobacteria-like calcite single crystals at the surface of the Tataouine meteorite

Geochemistry of diogenites: Still more diversity in their parental melts

The trapped noble gas component in achondrites

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