^1,2Ulli Raschke, ¹Ralf Thomas Schmitt, ³Iain McDonald, ^1,4Wolf Uwe Reimold, ⁵Dieter Mader, ^5,6Christian Koeberl
¹Museum für Naturkunde Berlin, Leibniz Institute for Evolution and Biodiversity Science, Berlin, Germany
² Freie Universität Berlin, Institut für Geologische Wissenschaften, Berlin, Germany
³School of Earth & Ocean Sciences, Cardiff University, Cardiff, UK
⁴Humboldt-Universität zu Berlin, Berlin, Germany
⁵Department of Lithospheric Research, Center for Earth Sciences, University of Vienna, Vienna, Austria
⁶Natural History Museum, Vienna, Austria

The complex impact structure El’gygytgyn (age 3.6 Ma, diameter 18 km) in northeastern Russia was formed in ~88 Ma old volcanic target rocks of the Ochotsk-Chukotsky Volcanic Belt (OCVB). In 2009, El’gygytgyn was the target of a drilling project of the International Continental Scientific Drilling Program (ICDP), and in summer 2011 it was investigated further by a Russian–German expedition. Drill core material and surface samples, including volcanic target rocks and impactites, have been investigated by various geochemical techniques in order to improve the record of trace element characteristics for these lithologies and to attempt to detect and constrain a possible meteoritic component. The bedrock units of the ICDP drill core reflect the felsic volcanics that are predominant in the crater vicinity. The overlying suevites comprise a mixture of all currently known target lithologies, dominated by felsic rocks but lacking a discernable meteoritic component based on platinum group element abundances. The reworked suevite, directly overlain by lake sediments, is not only comparatively enriched in shocked minerals and impact glass spherules, but also contains the highest concentrations of Os, Ir, Ru, and Rh compared to other El’gygytgyn impactites. This is—to a lesser extent—the result of admixture of a mafic component, but more likely the signature of a chondritic meteoritic component. However, the highly siderophile element contribution from target material akin to the mafic blocks of the ICDP drill core to the impactites remains poorly constrained.

Reference
Raschke U, Schmitt RT, McDonald I, Reimold WU, Mader D, Koeberl C (2015) Geochemical studies of impact breccias and country rocks from the El’gygytgyn impact structure, Russia. Meteoritics&Planetary Science (in Press)
Link to Article [DOI: 10.1111/maps.12455]

Published by arrangement with John Wiley&Sons