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Determining the age and possibility for an extraterrestrial impact formation mechanism of the Ilumetsa structures (Estonia)
Author(s) -
Losiak A.,
Jõeleht A.,
Plado J.,
Szyszka M.,
Kirsimäe K.,
Wild E. M.,
Steier P.,
Belcher C. M.,
Jazwa A. M.,
Helde R.
Publication year - 2020
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.13431
Subject(s) - impact crater , ejecta , impact structure , geology , extraterrestrial life , astrobiology , earth science , charcoal , circumstantial evidence , paleontology , geochemistry , archaeology , geography , astronomy , physics , materials science , supernova , metallurgy
The Ilumetsa site, in Estonia, consists of two round, rimmed structures that are 725 m apart. The structures are listed as proven impact craters in the Impact Earth database, despite lack of commonly accepted, unequivocal proof of extraterrestrial collision identified at this location. We excavated trenches though the Ilumetsa Large and Ilumetsa Small structures and found small pieces of charcoal within the putative proximal ejecta in both structures, in a similar geological setting as previously identified charcoal in Kaali (Losiak et al. 2016) and Morasko craters (see Szokaluk et al. 2019). Our 14 C dating of charcoal allowed us to conclude that these crater‐like features formed simultaneously between 7170 and 7000 cal. years bp , about 7 ka after deglaciation of this area. A ground penetrating radar survey of the nearby bog shows that no additional Ilumetsa structures bigger than 40 m exist. Geochemical studies of the ejecta and a search using a metal detector did not reveal any clear indication of extraterrestrial material. This suggests Ilumetsa may have been formed by an impact of stony‐iron or stony body, which got significantly weathered in a wet‐temperate climate. The mystery of the formation of the structures at Ilumetsa remains; however, due to significant circumstantial evidence discussed herein, we are confident to call it a “probable” impact site.