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Iridium anomaly but no shocked quartz from Late Archean microkrystite layer: Oceanic impact ejecta?

1998; Geological Society of America; Volume: 26; Issue: 3 Linguagem: Inglês

10.1130/0091-7613(1998)026 2.3.co;2

1943-2682

Bruce M. Simonson, D. A. Bryn Davies, Malcolm W. Wallace, Shane Reeves, S. W. Hassler,

Methane Hydrates and Related Phenomena

Research Article| March 01, 1998 Iridium anomaly but no shocked quartz from Late Archean microkrystite layer: Oceanic impact ejecta? Bruce M. Simonson; Bruce M. Simonson 1Department of Geology, Oberlin College, Oberlin, Ohio 44074-1044 Search for other works by this author on: GSW Google Scholar Darian Davies; Darian Davies 1Department of Geology, Oberlin College, Oberlin, Ohio 44074-1044 Search for other works by this author on: GSW Google Scholar Malcolm Wallace; Malcolm Wallace 2School of Earth Sciences, University of Melbourne, Parkville, Victoria 3052, Australia Search for other works by this author on: GSW Google Scholar Shane Reeves; Shane Reeves 2School of Earth Sciences, University of Melbourne, Parkville, Victoria 3052, Australia Search for other works by this author on: GSW Google Scholar Scott W. Hassler Scott W. Hassler 3Department of Geological Sciences, California State University, Hayward, California 94542 Search for other works by this author on: GSW Google Scholar Author and Article Information Bruce M. Simonson 1Department of Geology, Oberlin College, Oberlin, Ohio 44074-1044 Darian Davies 1Department of Geology, Oberlin College, Oberlin, Ohio 44074-1044 Malcolm Wallace 2School of Earth Sciences, University of Melbourne, Parkville, Victoria 3052, Australia Shane Reeves 2School of Earth Sciences, University of Melbourne, Parkville, Victoria 3052, Australia Scott W. Hassler 3Department of Geological Sciences, California State University, Hayward, California 94542 Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1998) 26 (3): 195–198. https://doi.org/10.1130/0091-7613(1998)026 2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Bruce M. Simonson, Darian Davies, Malcolm Wallace, Shane Reeves, Scott W. Hassler; Iridium anomaly but no shocked quartz from Late Archean microkrystite layer: Oceanic impact ejecta?. Geology 1998;; 26 (3): 195–198. doi: https://doi.org/10.1130/0091-7613(1998)026 2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Samples from a ca. 2.54 Ga layer rich in microkrystites (sand-size spherules of former silicate melt) in the Hamersley Group (Western Australia) are enriched in Ir up to 50 fold over associated carbonates and shales, but few of the other siderophile elements display significant anomalies or chondritic interelement ratios. However, similar concentrations and interelement ratios are observed in ejecta from the ca. 590 Ma Acraman impact structure and have been attributed to diagenetic redistribution. The microkrystite layer also contains sand-size quartz grains with internal textures typical of regionally metamorphosed rocks rather than evidence of shock metamorphism. We suggest that the microkrystites were created by an impact that took place in a deep ocean basin rather than on a continent, and that the associated quartz is epiclastic detritus brought in by unusually high energy waves and/or currents, not as ballistic ejecta. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.