The Eoarchean legacy of Isua (Greenland) worth preserving for future generations
The Eoarchean (> 3600 Ma, or millions of years ago) folded and metamorphosed Isua supracrustal belt and the adjacent orthogneiss exposures of Greenland contain rare low deformation lenses that display some uniquelypreserved components of Earth's oldest rock record. These include world's...
| Published in: | Earth-Science Reviews |
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| Main Authors: | , , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Elsevier
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| Subjects: | |
| Online Access: | http://hdl.handle.net/1885/205395 https://doi.org/10.1016/j.earscirev.2019.102923 https://openresearch-repository.anu.edu.au/bitstream/1885/205395/3/01_Nutman_The_Eoarchean_legacy_of_Isua_2019.pdf.jpg |
| Summary: | The Eoarchean (> 3600 Ma, or millions of years ago) folded and metamorphosed Isua supracrustal belt and the adjacent orthogneiss exposures of Greenland contain rare low deformation lenses that display some uniquelypreserved components of Earth's oldest rock record. These include world's oldest (but contested) stromatolites in dolomitic carbonates, conglomerates, pillow basalts demonstrating submarine eruption, slivers of upper mantle rocks, formation of earliest continental crust by multistage tonalite + diorite emplacement followed by intracrustal granite production. All these diverse occurrences are keys to establish early Earth's processes at the start of the geological record. Although some of these features are preserved at several localities, other critical ones are exposed on only a few m2 of rock at single localities or are of historical significance. None of these sites are currently protected, and there is a reliance on responsible sampling to keep them intact for future generations. Given the high interest in the Archean Eon, combined with the increased ease of fieldwork in remote localities, many significant 'Deep Time' localities in not only Greenland but worldwide are in danger of eradication. Here, five key Isua area geological sites are presented, with an explanation of their significance and worthiness for initially reliance on already-collected samples, but hopefully ultimately government protection. This highlights an increasing problem of destruction of in situ evidence of Earth's unique early geological heritage and the need for collaboration in protecting and archiving of these key scientific resources. This work on the Isua supracrustal belt is supported by Australian Research Council Discovery Grant DP170100715. |
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