Non-destructive spectroscopic and petrochemical investigations of Paleoarchean spherule layers from the ICDP Drill Core BARB5, Barberton Mountain Land, South Africa
- Author(s)
- Jörg Fritz, Roald Tagle, Luisa Ashworth, Ralf Thomas Schmitt, Axel Hofmann, Béatrice Luais, Phillip D. Harris, Desirée Hoehnel, Seda Özdemir, Tanja Mohr-Westheide, Christian Koeberl
- Abstract
A Paleoarchean impact spherule-bearing interval of the 763 m long International Continental Scientific Drilling Program (ICDP) drill core BARB5 from the lower Mapepe Formation of the Fig Tree Group, Barberton Mountain Land (South Africa) was investigated using nondestructive analytical techniques. The results of visual observation, infrared (IR) spectroscopic imaging, and micro-X-ray fluorescence (μXRF) of drill cores are presented. Petrographic and sedimentary features, as well as major and trace element compositions of lithologies from the micrometer to kilometer-scale, assisted in the localization and characterization of eight spherule-bearing intervals between 512.6 and 510.5 m depth. The spherule layers occur in a strongly deformed section between 517 and 503 m, and the rocks in the core above and below are clearly less disturbed. The μXRF element maps show that spherule layers have similar petrographic and geochemical characteristics but differences in (1) sorting of two types of spherules and (2) occurrence of primary minerals (Ni-Cr spinel and zircon). We favor a single impact scenario followed by postimpact reworking, and subsequent alteration. The spherule layers are Al
2O
3-rich and can be distinguished from the Al
2O
3-poor marine sediments by distinct Al-OH absorption features in the short wave infrared (SWIR) region of the electromagnetic spectrum. Infrared images can cover tens to hundreds of square meters of lithologies and, thus, may be used to search for Al-OH-rich spherule layers in Al
2O
3-poor sediments, such as Eoarchean metasediments, where the textural characteristics of the spherule layers are obscured by metamorphism.
- Organisation(s)
- Department of Lithospheric Research
- External organisation(s)
- Saalbau Weltraum Projekt, Museum für Naturkunde Berlin - Leibniz-Institut für Evolutions- und Biodiversitätsforschung, GeoSpectral Imaging, University of Johannesburg (UJ), Bruker Nano GmbH, Centre National De La Recherche Scientifique (CNRS)
- Journal
- Meteoritics and Planetary Science
- Volume
- 51
- Pages
- 2441–2458
- No. of pages
- 18
- ISSN
- 1086-9379
- DOI
- https://doi.org/10.1111/maps.12736
- Publication date
- 12-2016
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 105105 Geochemistry
- Keywords
- ASJC Scopus subject areas
- Geophysics, Space and Planetary Science
- Sustainable Development Goals
- SDG 15 - Life on Land
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/aba3d98a-d94c-4110-ab03-ad74bce735e7