Snapshot of an early Paleoproterozoic ecosystem

Two diverse microfossil communities from the Turee Creek Group, Western Australia

Erica Victoria Barlow, Martin Van Kranendonk

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Eighteen microfossil morphotypes from two distinct facies of black chert from a deep-water setting of the c. 2.4 Ga Turee Creek Group, Western Australia, are reported here. A primarily in situ, deep-water benthic community preserved in nodular black chert occurs as a tangled network of a variety of long filamentous microfossils, unicells of one size distribution and fine filamentous rosettes, together with relatively large spherical aggregates of cells interpreted as in-fallen, likely planktonic, forms. Bedded black cherts, in contrast, preserve microfossils primarily within, but also between, rounded clasts of organic material that are coated by thin, convoluted carbonaceous films interpreted as preserved extracellular polymeric substance (EPS). Microfossils preserved within the clasts include a wide range of unicells, both much smaller and larger than those in the nodular black chert, along with relatively short, often degraded filaments, four types of star-shaped rosettes and umbrella-like rosettes. Large, complexly branching filamentous microfossils are found between the clasts. The grainstone clasts in the bedded black chert are interpreted as transported from shallower water, and the contained microfossils thus likely represent a phototrophic community. Combined, the two black chert facies provide a snapshot of a microbial ecosystem spanning shallow to deeper-water environments, and an insight into the diversity of life present during the rise in atmospheric oxygen. The preserved microfossils include two new, distinct morphologies previously unknown from the geological record, as well as a number of microfossils from the bedded black chert that are morphologically similar to—but 400–500 Ma older than—type specimens from the c. 1.88 Ga Gunflint Iron Formation. Thus, the Turee Creek Group microfossil assemblage creates a substantial reference point in the sparse fossil record of the earliest Paleoproterozoic and demonstrates that microbial life diversified quite rapidly after the end of the Archean.

Original languageEnglish
Pages (from-to)449-475
Number of pages27
JournalGeobiology
Volume16
Issue number5
DOIs
Publication statusPublished - Sep 1 2018
Externally publishedYes

Fingerprint

microfossils
microfossil
Western Australia
chert
ecosystems
ecosystem
clast
deep water
water
creek
grainstone
microbial ecology
geological record
morphotype
cell aggregates
fossil record
films (materials)
benthos
preserves
branching

Keywords

  • community
  • ecosystem
  • Great Oxidation Event
  • Gunflint microbiota
  • microfossil
  • Turee Creek Group

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Environmental Science(all)
  • Earth and Planetary Sciences(all)

Cite this

Snapshot of an early Paleoproterozoic ecosystem : Two diverse microfossil communities from the Turee Creek Group, Western Australia. / Barlow, Erica Victoria; Van Kranendonk, Martin.

In: Geobiology, Vol. 16, No. 5, 01.09.2018, p. 449-475.

Research output: Contribution to journalArticle

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