Chromium isotope evidence in ejecta deposits for the nature of Paleoproterozoic impactors

• Published in: Earth and Planetary Science Letters
• Main Authors: Mougel, Bérengère, Moynier, Frédéric, Göpel, Christa, Koeberl, Christian
• Other Authors: Institut de Physique du Globe de Paris (IPGP (UMR_7154)), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Institut Universitaire de France (IUF), Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.), Department of Lithospheric Research Wien, Universität Wien, Natural History Museum Vienna (NHM), IPGP multidisciplinary program PARI, and the Region île-de-France SESAME for Grant no.12015908.IDEX13C445UnivEarthS Labex program ANR-10-LABX-0023ANR-11-IDEX-0005-02IPGP multidisciplinary program PARI Region Ile-de-France12015908, ANR-11-IDEX-0005,USPC,Université Sorbonne Paris Cité(2011), European Project: 637503,H2020,ERC-2014-STG,PRISTINE(2015)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2017
• Subjects: meteorite; impact ejecta; crater; chromium isotopes; Sudbury; Vredefort; [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry; [SDU.STU.PL]Sciences of the Universe [physics]/Earth Sciences/Planetology; Greenland
• Online Access: https://hal-insu.archives-ouvertes.fr/insu-02917511; https://hal-insu.archives-ouvertes.fr/insu-02917511/document; https://hal-insu.archives-ouvertes.fr/insu-02917511/file/1612.06922.pdf; https://doi.org/10.1016/j.epsl.2016.12.008

International audience Non-mass dependent chromium isotopic signatures have been successfully used to determine the presence and identification of extra-terrestrial materials in terrestrial impact rocks. Paleoproterozoic spherule layers from Greenland (Graensesø) and Russia (Zaonega), as well as some distal ejecta deposits (Lake Superior region) from the Sudbury impact (1,849±0.3 Ma) event, have been analyzed for their Cr isotope compositions. Our results suggest that 1) these distal ejecta deposits are all of impact origin, 2) the Graensesø and Zaonega spherule layers contain a distinct carbonaceous chondrite component, and are possibly related to the same impact event, which could be Vredefort (2,023±4 Ma) or another not yet identified large impact event 2 from that of similar age, and 3) the Sudbury ejecta record a complex meteoritic signature, which is different from the Graensesø and Zaonega spherule layers, and could indicate the impact of a heterogeneous chondritic body.