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 = University of Vienna, 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://insu.hal.science/insu-02917511; https://insu.hal.science/insu-02917511/document; https://insu.hal.science/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.