Highly siderophile elements (Re, Os, Ir, Ru, Rh, Pd, Au) in impact melts from three European impact craters (Sääksjärvi, Mien, and Dellen): Clues to the nature of the impacting bodies

Schmidt, Gerhard; Palme, H.; Kratz, K. L.

doi:10.1016/s0016-7037(97)00129-4

Cited by 75 publications

(83 citation statements)

References 30 publications

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“…However, this study revealed that target rock PGE concentrations were highly variable, and in some cases were very high (e.g., Ir up to 3 ppb and Pt up to 39 ppb). The PGE abundance pattern in these samples are fractionated when normalized to chondritic (meteorite) abundances and are enriched in the more volatile PGE and Au, in common with most crustal rocks (Barnes et al 1985;Schmidt et al 1997;Farago et al 2005). It should be noted that in the wider region around Bosumtwi there are several gold mines, and elevated siderophile element abundances are found in many regional country rocks (cf.…”

Section: Search For a Meteoritic Component At Bosumtwimentioning

confidence: 99%

Search for a meteoritic component in drill cores from the Bosumtwi impact structure, Ghana: Platinum group element contents and osmium isotopic characteristics

McDonald

Peucker‐Ehrenbrink

Coney

et al. 2007

Meteorit & Planetary Scien

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Abstract-An attempt was made to detect a meteoritic component in both crater-fill (fallback) impact breccias and fallout suevites (outside the crater rim) at the Bosumtwi impact structure in Ghana. Thus far, the only clear indication for an extraterrestrial component related to this structure has been the discovery of a meteoritic signature in Ivory Coast tektites, which formed during the Bosumtwi impact event. Earlier work at Bosumtwi indicated unusually high levels of elements that are commonly used for the identification of meteoritic contamination (i.e., siderophile elements, including the platinum group elements [PGE]) in both target rocks and impact breccias from surface exposures around the crater structure, which does not allow unambiguous verification of an extraterrestrial signature. The present work, involving PGE abundance determinations and Os isotope measurements on drill core samples from inside and outside the crater rim, arrives at the same conclusion. Despite the potential of the Os isotope system to detect even small amounts of extraterrestrial contribution, the wide range in PGE concentrations and Os isotope composition observed in the target rocks makes the interpretation of unradiogenic, high-concentration samples as an impact signature ambiguous.

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Section: Search For a Meteoritic Component At Bosumtwimentioning

confidence: 99%

Search for a meteoritic component in drill cores from the Bosumtwi impact structure, Ghana: Platinum group element contents and osmium isotopic characteristics

McDonald

Peucker‐Ehrenbrink

Coney

et al. 2007

Meteorit & Planetary Scien

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“…At this time, an analysis of all platinum group elements (PGE) was usually not done, mainly because of the difficulties in the determination of some of the elements, especially Ru, Rh, and Pt, at such low concentration levels. However, with improvements in the analytical techniques, the number of elements used for impactor identification steadily increased (e.g., Schmidt et al 1997;Norman et al 2002;Tagle and Claeys 2005) highlighting the relevance of a precise knowledge of the composition of possible projectiles. The most relevant elements are the platinum group elements (Os, Ir, Ru, Pt, Rh, and Pd) as well as Cr, Co, Ni, and Au (refer to the Element Ratios of the Different Chondrite Groups section for a detailed explanation why these elements were chosen).…”

Section: Introductionmentioning

confidence: 99%

A database of chondrite analyses including platinum group elements, Ni, Co, Au, and Cr: Implications for the identification of chondritic projectiles

Tagle

Berlin

2008

Meteorit & Planetary Scien

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Abstract-Siderophile elements have been used to constrain projectile compositions in terrestrial and lunar impact melt rocks. To obtain a better knowledge of compositional differences between potential chondritic projectile types, meteorite analyses of the elements Ru, Rh, Pd, Os, Ir, Pt, Cr, Co, Ni, and Au were gathered into a database. The presented compilation comprises 806 analyses of 278 chondrites including new ICP-MS analyses of Allende and two ordinary chondrites. Each data set was evaluated by comparing element ratios of meteorites from the same chondrite group. Characteristic element abundances and ratios were determined for each group. Features observed in the element abundance patterns can be linked directly to the presence of certain components, such as the abundance of refractory elements Os, Ir, and Ru correlating with the occurrence of refractory inclusions in CV, CO, CK, and CM chondrites. The refined characteristic element ratios appear to be representative not only for meteorites, but also for related asteroidal bodies. Chondrite element ratios were compared to previously published values from impact melt rocks of the Popigai and Morokweng impact structures confirming that an identification of the specific type of projectile (L and LL chondrite, respectively) is possible. The assessment for Morokweng is supported by the recent discovery of an LL chondrite fragment in the impact melt rocks. Ultimately, the database provides valuable information for understanding processes in the solar nebula as they are recorded in chondrites. A new type of complementarity between element patterns of CK and EH chondrites is suggested to be the result of condensation, redox, and transportation processes in the solar nebula.

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“…Attempts to identify the type of impactor have previously focused on the geochemistry of the impact rocks hosting the recondensed fraction. Studies include measurements and interelement ratios of siderophile elements, primarily the platinum group elements (PGE) (e.g., [11][12][13][14][15]) and Cr-isotope measurements (e.g., [16][17][18]). Both these methods have limitations and are not always successful in the identification of impactor type.…”

Section: Introductionmentioning

confidence: 99%

Extraterrestrial chromite in the resurge deposits of the early Late Ordovician Lockne crater, central Sweden

Alwmark

Schmitz

2007

Earth and Planetary Science Letters

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The distribution of extraterrestrial chromite grains (N63 μm) has been studied in the resurge deposit of the early Late Ordovician (458 Ma) Lockne impact structure in central Sweden. A 1-kg-sample of resurge sediment from the rim of the crater is extremely rich in extraterrestrial chromite. In total the sample contains N 125 chromium spinel grains kg − 1 , most grains being chromite. Due to post-depositional alterations, the origin of several of the grains is dubious, although it is clear that the major part of the chromites is of extraterrestrial origin (N 75 grains kg − 1 ), most likely derived from the impactor. The alterations are primarily due to the hydrothermal system induced by the impactor, with zinc enrichment in the chromites as the most common characteristic. The element chemistry of the least altered chromite grains indicates that the impactor was an ordinary L chondrite. This concurs with a suggested increase in the flux of L chondritic asteroids to Earth, following the disruption of the L chondrite parent body at ca. 470 Ma. More than 170 impact craters are known from around the Earth, but only few of the impactors have been identified, mainly due to the low survival rate of projectile material. Further studies of impact craters will reveal if survival of extraterrestrial chromite is unique for the Lockne structure.

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Highly siderophile elements (Re, Os, Ir, Ru, Rh, Pd, Au) in impact melts from three European impact craters (Sääksjärvi, Mien, and Dellen): Clues to the nature of the impacting bodies

Cited by 75 publications

References 30 publications

Search for a meteoritic component in drill cores from the Bosumtwi impact structure, Ghana: Platinum group element contents and osmium isotopic characteristics

Search for a meteoritic component in drill cores from the Bosumtwi impact structure, Ghana: Platinum group element contents and osmium isotopic characteristics

A database of chondrite analyses including platinum group elements, Ni, Co, Au, and Cr: Implications for the identification of chondritic projectiles

Extraterrestrial chromite in the resurge deposits of the early Late Ordovician Lockne crater, central Sweden

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