Chicxulub impact crater data from the Yucatán Peninsula in Mexico re-interpreted: evidence for an iron meteoritic asteroid as impactor
Notice bibliographique
Résumé
. IntroductionThe Cretaceous-Paleogene (K-Pg) mass extinction is marked globally by elevated concentrations of the platinum group elements (PGE), emplaced by a impact event 66.051 ± 0.031 Ma ago [1][2]. The 180- to 200-km-wide Chicxulub impact structure on the Yucatán Peninsula [3] is being considered as a possible impact crater that led to the global enrichment of PGE at the K-Pg boundary. The PGE signature (data from [4]) in the gray-green marlstone interval of Core 40R-1 recovered from Site M0077 on the Chicxulub peak ring in the Gulf of Mexico is distinctly different from a meteoritic component consistent with a chondritic impactor as well as the near-chondritic PGE abundance pattern at the European K-Pg boundary sites of Caravaca in Spain and Stevns Klint in Denmark. 2. Non-chondritic PGE abundance pattern at the Chicxulub impact structureThe PGE pattern (or inter-element ratios) from the upper transitional unit (TU; 616.58-616.60 mbsf) [4], Stevns Klint, Caravaca [5], Earth’s upper mantle, and crust [6][7], and the iron meteorite Mundrabilla [8] are shown in Figure 1. Unfortunately Rh was not determined. Significant differences can be seen, for example, in the Ru/Ir ratio (Table 1).While the K-Pg sediments from Europe show a subchondritic Ru/Ir ratio of about 1.3, the suprachondritic Ru/Ir ratios of sediments from core 40R-1 range from about 2 to 4 (Figures 1-4).The Ru/Ir ratio of about 4 was measured on two subsamples from a depth of 616.6 mbsf at the University of Tokyo in Komaba using a Thermo Element XR HR-ICP-MS. The Ru/Ir ratio of about 2 was measured by ID-MS on one sample (616.58 mbsf) at the Vrije Universiteit Brussel [4]. The iron meteorites Mundrabilla and Duchesne have Ru/Ir ratios of about 3 and 5, respectively [8].The signature of the upper TU from the drill core is similar to the PGE pattern from the irons Mundrabilla and Duchesne (Figure 4). This observation calls into question the Chicxulub impact structure as the source crater for the near-chondritic PGE ratios in European K-Pg boundary sites. The non-chondritic PGE ratios of the upper TU are evidence that the globally distributed iridium layer is not preserved in the Chicxulub impact structure. The most likely source for the PGEs in the upper TU of core 40R-1 sediments are Mundrabilla and Duchesne like iron impactors.3. Future studiesThe Ru isotope composition could be used as a powerful analytical tool alongside PGE ratios (especially the diagnostic Ru/Rh and Ir/Rh mass ratios [9]) to identify impactor signatures [10].4. ConclusionIt seems to have been different projectile types and different temporal events [11][12], that left the near-chondritic PGE abundance patterns in Europe and the iron meteoritic abundance pattern in the sediments of the Chicxulub impact crater. When talking about synchronicity, it is easily overlooked that enormous time spans of ±31 ka (uncertainties) are meant for events that took place about 66 Ma ago. However, relative dating of individual events and their correlation is possible with lithostratigraphy and biostratigraphy and can be supplemented, but not replaced, by radioisotope dating.References[1] Alvarez L. W., Alvarez W., Asaro F. & Michel H. V. (1980) Extraterrestrial cause for the Cretaceous-Tertiary extinction. Science 208, 1095 - 1108.[2] Renne P. R., Arenillas I., Arz J. A., Vajda V., Gilabert V. & Bermúdez H. D. (2018) Multi-proxy record of the Chicxulub impact at the Cretaceous-Paleogene boundary from Gorgonilla Island, Colombia. Geology 46, 547 - 550.[3] Hildebrand A. R., Penfield G. T., Kring D. A., Pilkingston M., Camargo Z. A., Jacobsen S. B. & Boynton W. V. (1991) Chicxulub Crater: A possible Cretaceous/Tertiary boundary impact crater on the Yucatán Peninsula, Mexico. Geology 19, 867 - 871.[4] Goderis S., Sato H., Ferrière L., Schmitz B., Burney D., Kaskes P., Vellekoop J., Wittmann A., Schulz T., Chernonozhkin S. M., Claeys P., de Graaff S. J., Déhais T., de Winter N. J., Elfman M., Feignon J.-G., Ishikawa A., Koeberl C., Kristiansson P., Neal C. R., Owens J. D., Schmieder M., Sinnesael M., Vanhaecke F., Van Malderen S. J. M., Bralower T. J., Gulick S. P. S., Kring D. A., Lowery C. M., Morgan J. V., Smit J., Whalen M. T. & IODP-ICDP Expedition 364 Scientists (2021) Globally distributed iridium layer preserved within the Chicxulub impact structure. Science Advances 7, eabe3647.[5] Lee C.-T. A., Wasserburg G.J. & Kyte F. (2003) Platinum-group elements (PGE) and rhenium in marine sediments across the Cretaceous–Tertiary boundary: Constraints on Re-PGE transport in the marine environment. Geochimica et Cosmochimica Acta 67, 655 - 670.[6] Schmidt G. (2004) Are high-temperature fractionations in the solar nebula preserved in highly siderophile element systematics of the Earth’s mantle? Meteoritics & Planetary Science 39, 1995 - 2007. [7] Schmidt G. & Palme H. (1998) The concentrations of highly siderophile elements in Earth's upper crust as inferred from the compositions of large terrestrial impact melt sheets. 29th Lunar and Planetary Science Conference, Abstract #1273[8] Petaev M.I. & Jacobsen S.B. (2004) Differentiation of metal‐rich meteoritic parent bodies: I. Measurements of PGEs, Re, Mo, W, and Au in meteoritic Fe‐Ni metal. Meteoritics & Planetary Science 39, 1685 - 1697.[9] Schmidt G. (2019) Ru/Rh and Ir/Rh as diagnostic mass ratios for the identification of specific impactor compositions of terrestrial impact craters. Paneth Kolloquium, Nördlingen (Germany), Abstract #0009[10] Schmidt G. (2019) Distinguishing different types of projectiles from terrestrial impact craters – Clearwater East (Canada) and Rochechouart (France) re-investigated. Large Meteorite Impacts and Planetary Evolution VI, Lunar and Planetary Institute Contribution No. 2136, Abstract #5006.[11] Keller G., Stinnesbeck W., Adatte T. & Stüben D. (2003) Multiple impacts across the Cretaceous–Tertiary boundary. Earth-Science Reviews 62, 327 - 363.[12] Keller G. (2005) Impacts, volcanism and mass extinction: Random coincidence or cause and effect? Australian Journal of Earth Sciences 52, 725 - 757.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 0,001 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,002 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».