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Origin of 3.45 Ga coniform stromatolites in Warrawoona Group, Western Australia

H. J. Hofmann, K. Grey, A. H. Hickman and R. I. Thorpe
Origin of 3.45 Ga coniform stromatolites in Warrawoona Group, Western Australia
Geological Society of America Bulletin (August 1999) 111 (8): 1256-1262


A new occurrence of conical and branched pseudocolumnar stromatolites in Archean dolostones in the Pilbara region, Australia, contributes significant new morphologic information on such structures. These remains are interpreted as probably representing, in part, microbially mediated accretionary growth surfaces in an Archean hypersaline depositional basin. The structures comprise laterally linked pseudocolumns of centimeter width and decimeter height, with first-order conical laminae of as much as 15 cm of synoptic relief and apical angles of 30 degrees -80 degrees . The conical laminae are modified by a second-order, centimeter-scale, low-amplitude primary corrugate lamination, with crests and troughs occasionally stacked to form satellitic, obliquely directed pseudocolumns; bedding surfaces exhibit a preferred direction of elongation of the cones, an orientation that is orthogonal (and unrelated) to the trend of younger folding; the microstructure is secondary. The stromatolites are better preserved than those previously known from chert in the Warrawoona succession. The remains exhibit certain distinct morphologic attributes corresponding to those in younger stromatolites, such as displayed by Thyssagetes and Jacutophyton, whose biogenicity is generally accepted (although difficult to demonstrate conclusively); the conical Warrawoona forms may represent the oldest known precursor of these taxa.

ISSN: 0016-7606
EISSN: 1943-2674
Serial Title: Geological Society of America Bulletin
Serial Volume: 111
Serial Issue: 8
Title: Origin of 3.45 Ga coniform stromatolites in Warrawoona Group, Western Australia
Affiliation: University of Montreal, Department of Geology, Montreal, QC, Canada
Pages: 1256-1262
Published: 199908
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 31
Accession Number: 1999-055509
Categories: Sedimentary petrologyStratigraphy
Document Type: Serial
Bibliographic Level: Analytic
Annotation: Geol. Surv. Can., Contrib. No. 1997274
Illustration Description: illus. incl. geol. sketch map
S22°00'00" - S21°00'00", E119°00'00" - E120°00'00"
Secondary Affiliation: Geological Survey of Western Australia, AUS, AustraliaGeological Survey of Canada, CAN, Canada
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 199919
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