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GEOREF RECORD

Impact spherules from Karelia, Russia; possible ejecta from the 2.02 Ga Vredefort impact event

Matthew S. Huber, Alenka E. Crne, Iain McDonald, Lutz Hecht, Victor A. Melezhik and Christian Koeberl
Impact spherules from Karelia, Russia; possible ejecta from the 2.02 Ga Vredefort impact event
Geology (Boulder) (March 2014) 42 (5): 375-378

Abstract

Spherule beds of possible impact origin have been discovered in two drill cores in the Paleoproterozoic Zaonega Formation, Karelia, northwest Russia. Spherules are found within the dolomite matrix of in-situ brecciated sedimentary dolostones. Spherules are millimeter size and generally round, although teardrop and dumbbell morphologies are present. Spherules contain up to 0.75 ppb Ir, with a Ru/Ir of 2, indicating a mixing of target rocks with a minor chondritic component. The age of the Zaonega Formation is constrained between limits of 1.975 + or - 0.024 Ga (Sm-Nd) and 1.980 + or - 0.057 Ga (Pb-Pb), and 2.050 Ga (Re-Os), which brackets the age of the 2020 Ma Vredefort impact structure in South Africa, and suggests that the spherule beds could represent ejecta from that event. If the link is confirmed, the size of the spherules and thickness of the beds suggest that the distance from the impact site was <2500 km, thereby constraining the paleogeographic distance between the Fennoscandian Shield and Kaapvaal craton during the late Paleoproterozoic.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 42
Serial Issue: 5
Title: Impact spherules from Karelia, Russia; possible ejecta from the 2.02 Ga Vredefort impact event
Affiliation: University of Vienna, Department of Lithospheric Research, Vienna, Austria
Pages: 375-378
Published: 20140321
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 24
Accession Number: 2014-028733
Categories: Sedimentary petrologyGeochemistry of rocks, soils, and sediments
Document Type: Serial
Bibliographic Level: Analytic
Annotation: GSA Data Repository item 2014141
Illustration Description: illus. incl. 1 table
N60°40'00" - N66°40'00", E29°19'60" - E37°55'00"
Secondary Affiliation: Geological Survey of Norway, NOR, NorwayCardiff University, GBR, United KingdomMuseum fuer Naturkunde Berlin, DEU, Germany
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2022, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201418
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