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The Late Ordovician (Sandbian) Glasford structure: A marine‐target impact crater with a possible connection to the Ordovician meteorite event
Author(s) -
Monson Charles C.,
Sweet Dustin,
Segvic Branimir,
Zai Giovanni,
Balling Kyle,
Wittmer Jacalyn M.,
Ganis G. Robert,
Cheng Guo
Publication year - 2019
Publication title -
meteoritics and planetary science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.09
H-Index - 100
eISSN - 1945-5100
pISSN - 1086-9379
DOI - 10.1111/maps.13401
Subject(s) - geology , impact crater , ordovician , impact structure , meteorite , paleontology , breccia , sedimentary depositional environment , sedimentary rock , ejecta , sedimentology , geochemistry , astrobiology , structural basin , physics , quantum mechanics , supernova
The Glasford structure in Illinois ( USA ) was recognized as a buried impact crater in the early 1960s but has never been reassessed in light of recent advances in planetary science. Here, we document shatter cones and previously unknown quartz microdeformation features that support an impact origin for the Glasford structure. We identify the 4 km wide structure as a complex buried impact crater and describe syn‐ and postimpact deposits from its annular trough. We have informally designated these deposits as the Kingston Mines unit ( KM ). The fossils and sedimentology of the KM indicate a marine depositional setting. The various intervals within the KM constitute a succession of breccia, carbonate, sandstone, and shale similar to marine sedimentary successions preserved in other craters. Graptolite specimens retrieved from the KM place the time of deposition at approximately 455 ± 2 Ma (Late Ordovician, Sandbian). This age determination suggests a possible link between the Glasford impact and the Ordovician meteorite shower, an increase in the rate of terrestrial meteorite impacts attributed to the breakup of the L‐chondrite parent body in the main asteroid belt.