کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5779880 | 1634696 | 2017 | 7 صفحه PDF | دانلود رایگان |
- Identification of impactors in paleoproterozoic ejecta deposits.
- Chromium isotope study of the Sudbury, Grænsesø and Zaonega ejecta layers.
- Links between paleoproterozoic ejecta, and the Sudbury and Vredefort impact events.
Non-mass dependent chromium isotopic signatures have been successfully used to determine the presence and identification of extra-terrestrial materials in terrestrial impact rocks. Paleoproterozoic spherule layers from Greenland (Grænsesø) and Russia (Zaonega), as well as some distal ejecta deposits (Lake Superior region) from the Sudbury impact (1849±0.3 Ma) event, have been analyzed for their Cr isotope compositions. Our results suggest that 1) these distal ejecta deposits are all of impact origin, 2) the Grænsesø and Zaonega spherule layers contain a distinct carbonaceous chondrite component, and are possibly related to the same impact event, which could be Vredefort (2023±4 Ma) or another not yet identified large impact event from that of similar age, and 3) the Sudbury ejecta record a complex meteoritic signature, which is different from the Grænsesø and Zaonega spherule layers, and could indicate the impact of a heterogeneous chondritic body.
Journal: Earth and Planetary Science Letters - Volume 460, 15 February 2017, Pages 105-111