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Are the 3,800-Myr-old Isua objects microfossils, limonite-stained fluid inclusions, or neither?

Nature

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DOI: 10.1038/293459a0

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Abstract

Bridgwater et al.1 issued a 'cautionary note' concerning several reports published by Pflug and co-workers2-5 describing objects called yeast-like microfossils (Isuasphaera isua Pflug) from a metamorphosed quartzite of the 3,800-Myr-old Isua supracrustal belt of south-west Greenland; Bridgwater et al. believe that the objects described by Pflug et al. 2-5 are 'indistinguishable from limonite-stained fluid inclusions' and hence are non-biogenic. I show here that the objects are neither limonite-stained fluid inclusions nor microfossils, but are limonite-stained cavities from the otherwise complete dissolution by weathering of ferruginous dolomite grains in these rocks. Several supporting arguments presented by both sides are believed to be invalid, and others are ambiguous. In view of the extensive research on the earliest life forms, and then significance to evolution, to early geochemical cycles and to the origin of the atmosphere and some ore deposits, the exact nature of the Isua objects, and particularly the validity of the evidence either for or against a biological origin, are of considerable importance. A careful evaluation of the evidence from Isua is particularly pertinent, as bona fide Precambrian fossils are also found in chemically similar (but much younger) silica-rich environments. ?? 1981 Nature Publishing Group.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Are the 3,800-Myr-old Isua objects microfossils, limonite-stained fluid inclusions, or neither?
Series title:
Nature
DOI:
10.1038/293459a0
Volume
293
Issue:
5832
Year Published:
1981
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Nature
First page:
459
Last page:
462
Number of Pages:
4