Английская Википедия:Ilumetsa crater

Материал из Онлайн справочника
Перейти к навигацииПерейти к поиску

Шаблон:Short description Шаблон:Infobox terrestrial impact site

Ilumetsa is a set of two probable meteorite craters[1] in Estonia. Шаблон:Ambiguous

The Ilumetsa site is located in south eastern Estonia and it consists of two structures, located 725 m from each other. Their diameters are: 75–80 m and ~50 m. Their true depths are about 8 and 3.5 m, respectively.[2] Both structures are surrounded by a rim up to a few meters high: the rims are highest in their eastern parts with maximum rim heights of Ilumetsa Large 4.5 m and 1.5 m for Ilumetsa Small.

The Large Ilumetsa structure has been dated by radiocarbon dating the gyttja and peat from the very bottom of the crater shaped depression.[3] The lowermost organic beds were dated to 6030 +/-100 14C years (7170– 6660 cal. years BP). Recent radiocarbon dating charcoals buried within assumed proximal ejecta blankets of these crater-like features showed Ilumetsa Large and Ilumetsa Small formed simultaneously between 7170 and 7000 cal. years BP.[4]

No clear meteorite fragments or shock metamorphic effects were ever found around those structures. Because of that Ilumetsa is not a proven impact crater. However, indirect lines of evidence are enough to call it a "probable" impact site. It is: 1) presence of deformed sedimentary beds (including the rim consisting of sands mixed with numerous clayey till lenses;[5], 2) only a small thickness of glacial sediments,[2] 3) simultaneous formation of both structures as showed by radiocarbon dating.[4]

References

Шаблон:Reflist

Шаблон:Impact cratering on Earth


Шаблон:Estonia-geo-stub