Search NASA⌕ Search

Engineering topics

Barghoorn, E. S.

Publications and source records attributed to Barghoorn, E. S..

6 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

Microfossil-like objects from the Archaean of Greenland - A cautionary note

Recent reports have described 'yeast-like microfossils' (Isuasphaera isua Pflug) in 3,800-million year old metaquartzites from the Isua supracrustal belt of south-west Greenland. A biogenic interpretation of these objects is inconsistent with the tectonic history of the Isua region, with the petrology of the metaquartzites, and with the morphology of the microstructures themselves. The putative microfossils are indistinguishable from limonite-stained fluid inclusions: microstructures which are demonstrably inorganic and post-depositional in origin. As such, it is contended that these objects should not be regarded as evidence of early Archaean life forms.

Bridgwater, D.↗
NASA NTRS1977

Variation in stable carbon isotopes in organic matter from the Gunflint Iron Formation

Results are presented for an isotopic analysis of the kerogen separated from 15 samples of the Gunflint Iron Formation, Ontario, and the conformably overlying Rove Formation. Reasons for which the Gunflint Iron Formation is suitable for such a study of a single Precambrian formation are identified. The general geology of the formation is outlined along with sample selection, description, and preparation. Major conclusions are that the basal Gunflint algal chert and shale facies are depleted in C-13 relative to the chert-carbonate and taconite facies, that differences in the delta C-13 values between Gunflint facies correlate with marked differences in their biological source materials as evidenced by their respective microbiotas, that the anthraxolites are anomalously depleted in C-13 relative to the kerogen of their encompassing cherts and shales, and that the effects of igneous intrusion and concomitant thermal alteration are shown by a marked loss of C-12 at the contact. The demonstration that not all kerogens are isotopically alike stresses the importance of facies data to the interpretation of C-13/C-12 ratios of ancient organic matter.

Barghoorn, E. S.↗
NASA NTRS1976

A Gunflint-type microbiota from the Duck Creek dolomite, Western Australia

Two-billion-year-old black chert lenses from the Duck Creek formation, northwestern Western Australia, contain abundant organically preserved microorganisms which are morphologically similar to fossils of approximately the same age from the Gunflint formation, Ontario. Entities include a relatively small (5-15 micron) coccoid taxon morphologically comparable to Huroniospora Barghoorn, a larger coccoid form comparable to an apparently planktonic alga from the Gunflint, Gunflintia Barghoorn, and Eoastrion Barghoorn (Metallogenium Perfil'ev). Gunflint-type assemblages had a wide geographic distribution in middle Precambrian times, and these assemblages may eventually prove useful as biostratigraphic indices.

Knoll, A. H.↗