Asteroid 2008 TC3 and the Fall of Almahata Sitta, a Unique Meteorite Breccia

Goodrich, C. A.; Bischoff, A.; O’Brien, D. P.

doi:10.2113/gselements.10.1.31

Cited by 32 publications

(30 citation statements)

References 24 publications

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“…; Goodrich et al. ; Horstmann and Bischoff ) or to the complex regolith breccias among the L‐ and LL‐group ordinary chondrites (Bischoff et al. , , ; Metzler et al.…”

Section: Discussionmentioning

confidence: 99%

The Stubenberg meteorite—An LL6 chondrite fragmental breccia recovered soon after precise prediction of the strewn field

Bischoff

Barrat

Bauer

et al. 2017

Meteorit & Planetary Scien

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On March 6, 2016 at 21:36:51 UT, extended areas of Upper Austria, Bavaria (Germany) and the southwestern part of the Czech Republic were illuminated by a very bright bolide. This bolide was recorded by instruments in the Czech part of the European Fireball Network and it enabled complex and precise description of this event including prediction of the impact area. So far six meteorites totaling 1473 g have been found in the predicted area. The first pieces were recovered on March 12, 2016 on a field close to the village of Stubenberg (Bavaria). Stubenberg is a weakly shocked (S3) fragmental breccia consisting of abundant highly recrystallized rock fragments embedded in a clastic matrix. The texture, the large grain size of plagioclase, and the homogeneous compositions of olivine (Fa31.4) and pyroxene (Fs25.4) clearly indicate that Stubenberg is an LL6 chondrite breccia. This is consistent with the data on O, Ti, and Cr isotopes. Stubenberg does not contain solar wind‐implanted noble gases. Data on the bulk chemistry, IR spectroscopy, cosmogenic nuclides, and organic components also indicate similarities to other metamorphosed LL chondrites. Noble gas studies reveal that the meteorite has a cosmic ray exposure (CRE) age of 36 ± 3 Ma and that most of the cosmogenic gases were produced in a meteoroid with a radius of at least 35 cm. This is larger than the size of the meteoroid which entered the Earth's atmosphere, which is constrained to <20 cm from short‐lived radionuclide data. In combination, this might suggest a complex exposure history for Stubenberg.

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“…; Goodrich et al. ; Horstmann and Bischoff ) or to the complex regolith breccias among the L‐ and LL‐group ordinary chondrites (Bischoff et al. , , ; Metzler et al.…”

Section: Discussionmentioning

confidence: 99%

The Stubenberg meteorite—An LL6 chondrite fragmental breccia recovered soon after precise prediction of the strewn field

Bischoff

Barrat

Bauer

et al. 2017

Meteorit & Planetary Scien

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“…; Goodrich et al. ; Horstmann and Bischoff ) bearing the potential of a mixing relation of constituents. In the following, several arguments are compiled to clearly show that there is (1) no link between the ureilite precursor material and E chondrites and (2) no intimate mixing relation (e.g., mobilized metal and/or sulfides) of Almahata Sitta fine‐grained ureilites and E chondrites: In general, (1) ureilites are somewhat enigmatic igneous rocks whose oxygen and osmium isotope data suggest a link to carbonaceous chondrites (Clayton and Mayeda ; Rankenburg et al.…”

Section: Discussionmentioning

confidence: 99%

“…; Goodrich et al. ; see Horstmann and Bischoff for a review). The ureilites recovered exhibit an impressive range of both textures and chemical compositions.…”

Section: Introductionmentioning

confidence: 99%

Si‐bearing metal and niningerite in Almahata Sitta fine‐grained ureilites and insights into the diversity of metal on the ureilite parent body

Horstmann

Humayun

Fischer-Gödde

et al. 2014

Meteorit & Planetary Scien

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A detailed mineralogical and chemical study of Almahata Sitta fine-grained ureilites was performed to shed light on the origin of these lithologies and their sulfide and metal. The Almahata Sitta fine-grained ureilites (silicates <30 lm grain size) show textural and chemical evidence for severe impact smelting as described for other fine-grained ureilites. Highly reduced areas in Almahata Sitta finegrained ureilites show large (up to $ 1 mm) Si-bearing metal grains (up to $ 4.5 wt% Si) and niningerite [Mg >0.5, (Mn,Fe) <0.5 S] with some similarities to the mineralogy of enstatite (E) chondrites. Overall, metal grains show a large compositional variability in Ni and Si concentrations. Niningerite grains probably formed as a by-product of smelting via sulfidation. The large Si-Ni variation in fine-grained ureilite metal could be the result of variable degrees of reduction during impact smelting, inherited from coarsegrained ureilite precursors, or a combination of both. Large Si-bearing metal grains probably formed via coalescence of existing and newly formed metal during impact smelting. Bulk and in situ siderophile trace element abundances indicate three distinct populations of (1) metal crystallized from partial melts in MS-20, (2) metal resembling bulk chondritic compositions in MS-165, and (3) residual metal in MS-168. Almahata Sitta fine-grained ureilites developed their distinctive mineralogy due to severe reduction during smelting. Despite the presence of E chondrite and ureilite stones in the Almahata Sitta fall, a mixing relation of E chondrites or their constituents and ureilite material in Almahata Sitta can be ruled out based on isotopic, textural, and mineral-chemical reasons.

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“…For example, Almahata Sitta meteorite, which fell in October 2008 in Sudan, is a polymict ureilite consisting of centimeter-to decimeter-sized fragments of different types of ureilites and various chondrites (Jenniskens et al 2009;Zolensky et al 2010;Bischoff et al 2010). The detailed studies of Almahata Sitta lead to a scenario involving break-up of a large ureilite parent body whose original diameter was larger than 200 km and reaccumulation into smaller daughter bodies (e.g., Bischoff et al 2010;Herrin et al 2010;Mikouchi et al 2010;Zolensky et al 2010;Goodrich et al 2014;Horstmann and Bischoff 2014). The parent asteroid of Almahata Sitta, asteroid 2008 TC3, is considered to have been a smaller rubble-pile block of these daughter bodies in which fragments were loosely packed, as evidenced by the fact that no recovered stones consisted of more than one lithology.…”

Section: Introductionmentioning

confidence: 99%

Mineralogy and crystallography of some Itokawa particles returned by the Hayabusa asteroidal sample return mission

et al. 2014

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We studied seven Itokawa particles provided by the Japan Aerospace Exploration Agency (JAXA) as first International Announcement of Opportunity (AO) study mainly using electron and synchrotron radiation X-ray beam techniques. All the analyzed particles were collected from the first-touchdown site and composed of olivine and plagioclase with traces of Ca phosphate and chromite, and do not contain pyroxenes. Optical microscopy of these particles shows minor undulatory extinction of olivine and plagioclase, suggesting minor shock metamorphism (shock stage: S2). The electron microprobe analysis shows that olivine is

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Asteroid 2008 TC3 and the Fall of Almahata Sitta, a Unique Meteorite Breccia

Cited by 32 publications

References 24 publications

The Stubenberg meteorite—An LL6 chondrite fragmental breccia recovered soon after precise prediction of the strewn field

The Stubenberg meteorite—An LL6 chondrite fragmental breccia recovered soon after precise prediction of the strewn field

Si‐bearing metal and niningerite in Almahata Sitta fine‐grained ureilites and insights into the diversity of metal on the ureilite parent body

Mineralogy and crystallography of some Itokawa particles returned by the Hayabusa asteroidal sample return mission

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