An examination of spherulitic dubiomicrofossils in Precambrian banded iron formations using the transmission electron microscope

Peter J. Heaney, David R. Veblen

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

The discovery of microfossils from the banded iron-formations of southern Ontario (Tyler and Barghoorn, 1954) has spurred many researchers to attribute a biogenic origin to a great variety of unusual structures in Precambrian BIFs. In particular, LaBerge (1973) has argued that jaspery and sideritic spherulites common to all major BIF deposits represent the fossilized remains of a unicellular blue-green algae of the Early Proterozoic, Eosphaera tyleri. Oehler (1976b), on the other hand, regards such structures as crystallization products of a viscous and impure silica gel. Examination of these 30-μm spherulites with a transmission electron microscope sheds doubt on both interpretations. Our analysis suggests that the jaspery spheres formed from the local recrystallization of the chert-hematite matrix after contact with an infiltrating fluid; thus, these structures are best viewed as diagenetic features. On the other hand, we discovered that the sideritic spheres contain cores of apatite; consequently, these spheres may have a biogenic origin, though the abundance of phosphate would indicate that they are not fossils of individual cells.

Original languageEnglish (US)
Pages (from-to)355-372
Number of pages18
JournalPrecambrian Research
Volume49
Issue number3-4
DOIs
StatePublished - Jan 1 1991

Fingerprint

banded iron formation
spherulite
Precambrian
Electron microscopes
Iron
electron
Apatites
Silica Gel
chert
microfossil
Crystallization
Contacts (fluid mechanics)
hematite
apatite
cyanobacterium
Proterozoic
crystallization
Deposits
gel
silica

All Science Journal Classification (ASJC) codes

  • Geology
  • Geochemistry and Petrology

Cite this

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abstract = "The discovery of microfossils from the banded iron-formations of southern Ontario (Tyler and Barghoorn, 1954) has spurred many researchers to attribute a biogenic origin to a great variety of unusual structures in Precambrian BIFs. In particular, LaBerge (1973) has argued that jaspery and sideritic spherulites common to all major BIF deposits represent the fossilized remains of a unicellular blue-green algae of the Early Proterozoic, Eosphaera tyleri. Oehler (1976b), on the other hand, regards such structures as crystallization products of a viscous and impure silica gel. Examination of these 30-μm spherulites with a transmission electron microscope sheds doubt on both interpretations. Our analysis suggests that the jaspery spheres formed from the local recrystallization of the chert-hematite matrix after contact with an infiltrating fluid; thus, these structures are best viewed as diagenetic features. On the other hand, we discovered that the sideritic spheres contain cores of apatite; consequently, these spheres may have a biogenic origin, though the abundance of phosphate would indicate that they are not fossils of individual cells.",
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An examination of spherulitic dubiomicrofossils in Precambrian banded iron formations using the transmission electron microscope. / Heaney, Peter J.; Veblen, David R.

In: Precambrian Research, Vol. 49, No. 3-4, 01.01.1991, p. 355-372.

Research output: Contribution to journalArticle

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