1,721,060 research outputs found
Replication Data for: Modal abundances of coarse-grained (>5 µm) components within CI-chondrites and their individual clasts – Mixing of various lithologies on the CI parent body(ies).
No full textAbstract:
For the bulk rocks of CI chondrites, various values are given for the modal abundance of matrix (95–100 vol%) and the accompanying mineral constituents. Here, we have determined the modal abundance of phases >5 μm in the CI chondrites Orgueil, Ivuna, Alais, and Tonk. Considering this cut-off grain-size to distinguish between matrix and coarse-grained constituents, then, we find the modal abundance of the minor phases magnetite, pyrrhotite, carbonate, olivine, and pyroxene to be 6 vol% in total, and these phases are embedded within the fine-grained, phyllosilicate-rich matrix, making up 94 vol%. The values vary slightly from meteorite to meteorite. Considering all four chondrites, the most abundant phase is - by far - magnetite (4.3 vol%) followed by pyrrhotite (∼1.1 vol%). All four CI chondrites are complex breccias, and their degree of brecciation decreases in the sequence: Orgueil > Ivuna > Alais ∼ Tonk. Because these meteorites contain clasts with highly variable modal abundances, we therefore also studied individual clasts with high abundances of specific coarse-grained phases. In this respect, in Orgueil we found a fragment with a 21.5 vol% of magnetite as well as a clast having 31.8 vol% phosphate. In Ivuna, we detected an individual clast with a 21.5 vol% of carbonates. Thus, since the CI composition is used as a geochemical standard for comparison, one also should keep in mind that sufficiently large sample masses are required to reveal a homogeneous CI composition. Small aliquots with one dominating lithology may significantly deviate from the suggested standard CI composition.
TRR 170 no. 7
Replication Data for: Shock stage distribution of 2280 ordinary chondrites – Can bulk chondrites with a shock stage of S6 exist as individual rocks?
No full textAbstract:
The brecciation and shock classification of 2280 ordinary chondrites of the meteorite thin section collection at the Institut für Planetologie (Münster) has been determined. The shock degree of S3 is the most abundant shock stage for the H and LL chondrites (44% and 41%, respectively), while the L chondrites are on average more heavily shocked having more than 40% of rocks of shock stage S4. Among the H and LL chondrites, 40–50% are “unshocked” or “very weakly shocked.” Considering the petrologic types, in general, the shock degree is increasing with petrologic type. This is the case for all meteorite groups. The main criteria to define a rock as an S6 chondrite are the solid‐state recrystallization and staining of olivine and the melting of plagioclase often accompanied by the formation of high‐pressure phases like ringwoodite. These characteristics are typically restricted to local regions of a bulk chondrite in or near melt zones. In the past, the identification of high‐pressure minerals (e.g., ringwoodite) was often taken as an automatic and practical criterion for a S6 classification during chondrite bulk rock studies. The shock stage classification of many significantly shocked chondrites (>S3) revealed that most ringwoodite‐bearing rocks still contain more than 25% plagioclase (74%). Thus, these bulk chondrites do not even fulfill the S5 criterion (e.g., 75% of plagioclase has to be transformed into maskelynite) and have to be classified as S4. Studying chondrites on typically large thin sections (several cm2) and/or using samples from different areas of the meteorites, bulk chondrites of shock stage S6 should be extremely rare. In this respect, the paper will discuss the probability of the existence of bulk rocks of S6.
TRR 170 no. 5
Replication Data for: Hydrogen isotopic composition of CI- and CM-like clasts from meteorite breccias – Sampling unknown sources of carbonaceous chondrite materials
No full textVolatile-rich, CI- and CM-like clasts occur in different brecciated achondrite and chondrite groups. The CI-like clasts in HEDs, polymict ureilites, as well as ordinary, CR, and CB chondrites have a similar mineralogy, indicating a similar alteration history. However, when viewed in detail, their mineral chemistry shows some minor differences between the clasts from different meteorite groups. For CM-like clasts found in HED meteorites, the clasts are, based on their mineralogy, clearly fragments of CM chondrites. To be able to decipher whether CI- (or CM-)like clasts from different meteorite groups are related to certain meteorite classes known to contain volatiles, we obtained D/H ratios of several clasts from the meteorite groups mentioned above and compared them with those of CI and CM chondrites as well as to unique carbonaceous chondrites such as Bells, Essebi, and Tagish Lake. Considering the δD-values, CM-like clasts in HEDs span a similar range compared to bulk values of CM chondrites, further indicating that CM-like clasts are fragments of CM chondrites. For CI-like clasts a clear distinction can be made: While CI-like clasts in HEDs and ordinary chondrites show a very similar range in their δD-signatures compared to “common” CI chondrites, meaning that these clasts are likely related to CI chondrites, the CI-like clasts in polymict ureilites are enriched in D up to 3000‰; a similarly high enrichment is found for the CI-like clasts in CR chondrites. Thus, although the CI-like clasts in ureilites and CR chondrites likely experienced similar alteration histories as the CI-like clasts found in the other meteorite types, these clasts probably formed in a different region than the CI chondrites and, thus, are more accurately referred to as C1 clasts. Overall, the existence and isotopic signatures of the C1 clasts in several meteorite groups proves the existence of additional primitive, volatile-rich material in the (early) Solar System besides the matter we study as the CI, CM, and CR chondrites. This material was distributed throughout the Solar System very early and might have played an important role for the volatile inventory of the terrestrial planets
Replication Data for: Mineralogy of volatile-rich clasts in brecciated meteorites
No full textMeteoritic breccias are valuable samples as they can contain rare materials from the early solar system as clasts. Volatile-rich, CI- and CM-like clasts may represent parent body lithologies, which cannot be found as individual meteorites in today's meteorite collections. In order to reveal a better knowledge about the presence and chemical characteristics and variability of volatile (water-bearing) materials in the early solar system these clasts play an important role. Such materials may have been available as the volatile component during the accretion of terrestrial planets. To understand the distribution of volatile-rich materials in the solar system, we studied CI- and CM-like clasts in brecciated meteorites including polymict ureilites, HEDs, CR, CB, CH, and ordinary chondrites. CI-like clasts occur throughout all of the mentioned meteorite groups, whereas the CM-like clasts have only been identified in HEDs and ordinary chondrites. The abundance of volatile-rich clasts in general decreases in the order CH > CR > ureilites > HEDs > CB > OC > R. The mineralogy of CI-like clasts is similar to CI chondrites, but their compositions of phyllosilicates differ. The mineralogy of CM-like clasts clearly links them to CM chondrites. They must have been delivered to the HED parent body by low-velocity impacts after differentiation and volcanism, as there is no evidence for high shock and heating processes. Additionally, we propose that CI-like clasts in the CR, CB, and CH chondrites are a primary component of the appropriate parent bodies (accretionary breccias). Conversely, the CI-like clasts in polymict ureilites and HEDs represent an infall as (micro)meteorites or as low-velocity impactors, which happened after the accretion and differentiation of the appropriate parent bodies
Replication Data for: Mineralogy of volatile-rich clasts in brecciated meteorites
No full textMeteoritic breccias are valuable samples as they can contain rare materials from the early solar system as clasts. Volatile-rich, CI- and CM-like clasts may represent parent body lithologies, which cannot be found as individual meteorites in today's meteorite collections. In order to reveal a better knowledge about the presence and chemical characteristics and variability of volatile (water-bearing) materials in the early solar system these clasts play an important role. Such materials may have been available as the volatile component during the accretion of terrestrial planets. To understand the distribution of volatile-rich materials in the solar system, we studied CI- and CM-like clasts in brecciated meteorites including polymict ureilites, HEDs, CR, CB, CH, and ordinary chondrites. CI-like clasts occur throughout all of the mentioned meteorite groups, whereas the CM-like clasts have only been identified in HEDs and ordinary chondrites. The abundance of volatile-rich clasts in general decreases in the order CH > CR > ureilites > HEDs > CB > OC > R. The mineralogy of CI-like clasts is similar to CI chondrites, but their compositions of phyllosilicates differ. The mineralogy of CM-like clasts clearly links them to CM chondrites. They must have been delivered to the HED parent body by low-velocity impacts after differentiation and volcanism, as there is no evidence for high shock and heating processes. Additionally, we propose that CI-like clasts in the CR, CB, and CH chondrites are a primary component of the appropriate parent bodies (accretionary breccias). Conversely, the CI-like clasts in polymict ureilites and HEDs represent an infall as (micro)meteorites or as low-velocity impactors, which happened after the accretion and differentiation of the appropriate parent bodies
Replication Data for: Hydrogen isotopic composition of CI- and CM-like clasts from meteorite breccias – Sampling unknown sources of carbonaceous chondrite materials
No full textVolatile-rich, CI- and CM-like clasts occur in different brecciated achondrite and chondrite groups. The CI-like clasts in HEDs, polymict ureilites, as well as ordinary, CR, and CB chondrites have a similar mineralogy, indicating a similar alteration history. However, when viewed in detail, their mineral chemistry shows some minor differences between the clasts from different meteorite groups. For CM-like clasts found in HED meteorites, the clasts are, based on their mineralogy, clearly fragments of CM chondrites. To be able to decipher whether CI- (or CM-)like clasts from different meteorite groups are related to certain meteorite classes known to contain volatiles, we obtained D/H ratios of several clasts from the meteorite groups mentioned above and compared them with those of CI and CM chondrites as well as to unique carbonaceous chondrites such as Bells, Essebi, and Tagish Lake. Considering the δD-values, CM-like clasts in HEDs span a similar range compared to bulk values of CM chondrites, further indicating that CM-like clasts are fragments of CM chondrites. For CI-like clasts a clear distinction can be made: While CI-like clasts in HEDs and ordinary chondrites show a very similar range in their δD-signatures compared to “common” CI chondrites, meaning that these clasts are likely related to CI chondrites, the CI-like clasts in polymict ureilites are enriched in D up to 3000‰; a similarly high enrichment is found for the CI-like clasts in CR chondrites. Thus, although the CI-like clasts in ureilites and CR chondrites likely experienced similar alteration histories as the CI-like clasts found in the other meteorite types, these clasts probably formed in a different region than the CI chondrites and, thus, are more accurately referred to as C1 clasts. Overall, the existence and isotopic signatures of the C1 clasts in several meteorite groups proves the existence of additional primitive, volatile-rich material in the (early) Solar System besides the matter we study as the CI, CM, and CR chondrites. This material was distributed throughout the Solar System very early and might have played an important role for the volatile inventory of the terrestrial planets
Replication Data for: Hydrogen isotopic composition of CI- and CM-like clasts from meteorite breccias – Sampling unknown sources of carbonaceous chondrite materials
No full textVolatile-rich, CI- and CM-like clasts occur in different brecciated achondrite and chondrite groups. The CI-like clasts in HEDs, polymict ureilites, as well as ordinary, CR, and CB chondrites have a similar mineralogy, indicating a similar alteration history. However, when viewed in detail, their mineral chemistry shows some minor differences between the clasts from different meteorite groups. For CM-like clasts found in HED meteorites, the clasts are, based on their mineralogy, clearly fragments of CM chondrites. To be able to decipher whether CI- (or CM-)like clasts from different meteorite groups are related to certain meteorite classes known to contain volatiles, we obtained D/H ratios of several clasts from the meteorite groups mentioned above and compared them with those of CI and CM chondrites as well as to unique carbonaceous chondrites such as Bells, Essebi, and Tagish Lake. Considering the δD-values, CM-like clasts in HEDs span a similar range compared to bulk values of CM chondrites, further indicating that CM-like clasts are fragments of CM chondrites. For CI-like clasts a clear distinction can be made: While CI-like clasts in HEDs and ordinary chondrites show a very similar range in their δD-signatures compared to “common” CI chondrites, meaning that these clasts are likely related to CI chondrites, the CI-like clasts in polymict ureilites are enriched in D up to 3000‰; a similarly high enrichment is found for the CI-like clasts in CR chondrites. Thus, although the CI-like clasts in ureilites and CR chondrites likely experienced similar alteration histories as the CI-like clasts found in the other meteorite types, these clasts probably formed in a different region than the CI chondrites and, thus, are more accurately referred to as C1 clasts. Overall, the existence and isotopic signatures of the C1 clasts in several meteorite groups proves the existence of additional primitive, volatile-rich material in the (early) Solar System besides the matter we study as the CI, CM, and CR chondrites. This material was distributed throughout the Solar System very early and might have played an important role for the volatile inventory of the terrestrial planets
Replication Data for: Mineralogy of volatile-rich clasts in brecciated meteorites
No full textMeteoritic breccias are valuable samples as they can contain rare materials from the early solar system as clasts. Volatile-rich, CI- and CM-like clasts may represent parent body lithologies, which cannot be found as individual meteorites in today's meteorite collections. In order to reveal a better knowledge about the presence and chemical characteristics and variability of volatile (water-bearing) materials in the early solar system these clasts play an important role. Such materials may have been available as the volatile component during the accretion of terrestrial planets. To understand the distribution of volatile-rich materials in the solar system, we studied CI- and CM-like clasts in brecciated meteorites including polymict ureilites, HEDs, CR, CB, CH, and ordinary chondrites. CI-like clasts occur throughout all of the mentioned meteorite groups, whereas the CM-like clasts have only been identified in HEDs and ordinary chondrites. The abundance of volatile-rich clasts in general decreases in the order CH > CR > ureilites > HEDs > CB > OC > R. The mineralogy of CI-like clasts is similar to CI chondrites, but their compositions of phyllosilicates differ. The mineralogy of CM-like clasts clearly links them to CM chondrites. They must have been delivered to the HED parent body by low-velocity impacts after differentiation and volcanism, as there is no evidence for high shock and heating processes. Additionally, we propose that CI-like clasts in the CR, CB, and CH chondrites are a primary component of the appropriate parent bodies (accretionary breccias). Conversely, the CI-like clasts in polymict ureilites and HEDs represent an infall as (micro)meteorites or as low-velocity impactors, which happened after the accretion and differentiation of the appropriate parent bodies
Replication Data for: The old, unique C1 chondrite Flensburg – insight into the first processes of aqueous alteration, brecciation, and the diversity of water-bearing parent bodies and lithologies.
No full textAbstract:
On September 12, 2019 at 12:49:48 (UT) a bolide was observed by hundreds of eye-witnesses from the Netherlands, Germany, Belgium, Denmark and the UK. One day later a small meteorite stone was found by accident in Flensburg. The presence of short-lived cosmogenic radionuclides with half-lives as short as 16 days proves the recent exposure of the found object to cosmic rays in space linking it clearly to the bolide event. An exceptionally short exposure time of ∼5000 years was determined. The 24.5 g stone has a fresh black fusion crust, a low density of
In the three oxygen isotope diagram, Flensburg plots at the 16O-rich end of the CM chondrite field and in the transition field to CV-CK-CR chondrites. The mass-dependent Te isotopic composition of Flensburg is slightly different from mean CM chondrites and is most similar to those of the ungrouped C2 chondrite Tagish Lake. On the other hand, 50Ti and 54Cr isotope anomalies indicate that Flensburg is similar to CM chondrites, as do the ∼10 wt.% H2O of the bulk material. Yet, the bulk Zn, Cu, and Pb concentrations are about 30% lower than those of mean CM chondrites. The He, Ne, and Ar isotopes of Flensburg show no solar wind contribution; its trapped noble gas signature is similar to that of CMs with a slightly lower concentration of 20Netr.
Based on the bulk H, C, and N elemental abundances and isotopic compositions, Flensburg is unique among chondrites, because it has the lightest bulk H and N isotopic compositions of any type 1 or 2 chondrite investigated so far. Moreover, the number of soluble organic compounds in Flensburg is even lower than that of the brecciated CI chondrite Orgueil.
The extraordinary significance of Flensburg is evident from the observation that it represents the oldest chondrite sample in which the contemporaneous episodes of aqueous alteration and brecciation have been preserved. The characterization of a large variety of carbonaceous chondrites with different alteration histories is important for interpreting returned samples from the OSIRIS-REx and Hayabusa 2 missions
Replication Data for: The Renchen L5-6 chondrite breccia – The first confirmed meteorite fall from Baden-Württemberg (Germany).
No full textOn July 10, 2018 at 21:29 UT extended areas of South-Western Germany were illuminated by a very bright bolide. This fireball was recorded by instruments of the European Fireball Network (EN). The records enabled complex and precise description of this event including the prediction of the impact area. So far six meteorites totaling about 1.23 kg have been found in the predicted location for a given mass during dedicated searches. The first piece of about 12 g was recovered on July 24 close to the village of Renchen (Baden-Württemberg) followed by the largest fragment of 955 g on July 31 about five km north-west of Renchen.
Renchen is a moderately-shocked (S4) breccia consisting of abundant highly recrystallized rock fragments as well as impact melt rock clasts. The texture, the large grain size of plagioclase, and the homogeneous compositions of olivine (∼Fa26) and pyroxene (∼Fs22) clearly indicate that Renchen is composed of metamorphosed rock fragments (L5–6). An L-group (and ordinary chondrite) heritage is consistent with the data on the model abundance of metal, the density, the magnetic susceptibility as well as on O-, Ti-, and Cr-isotope characteristics. Renchen does not contain solar wind implanted noble gases and is a fragmental breccia. An unusually large mm-sized merrillite-apatite aggregate shows trace element characteristics like other phosphates from ordinary chondrites.
Data on the bulk chemistry, IR-spectroscopy, cosmogenic nuclides, and organic components also indicate similarities to other metamorphosed L chondrites. Noble gas studies reveal that the meteorite has a cosmic ray exposure (CRE) age of 42 Ma and that most of the cosmogenic gases were produced in a meteoroid with a radius of at max. 20 cm based on the radionuclide 26Al and 10–150 cm based on cosmogenic 22Ne/21Ne. K-Ar and U/Th-He gas retention ages are both in the range ∼3.0–3.2 Ga. Both systems do not show evidence for a complete reset 470 Ma ago, and may instead have recorded the same resetting event 3.0 Ga ago.
TRR 170 no. 6
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