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Gunflint chert

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Title: Gunflint chert  
Author: World Heritage Encyclopedia
Language: English
Subject: History of the Rove Formation, Chert, Schreiber, Ontario, Slate Islands (Ontario)
Publisher: World Heritage Encyclopedia

Gunflint chert

The Gunflint chert (1.88 Ga[1]) is a sequence of banded iron formation rocks that are exposed in the Gunflint Range of northern Minnesota and northwestern Ontario along the north shore of Lake Superior. The black layers in the sequence contain microfossils that are 1.9 to 2.3 billion years in age. Stromatolite colonies of cyanobacteria that have been converted to jasper are found in Ontario. The banded ironstone formation consists of alternating strata of iron oxide-rich layers interbedded with silica-rich zones. The iron oxides are typically hematite or magnetite with ilmenite, while the silicates are predominantly cryptocrystalline quartz as chert or jasper, along with some minor silicate minerals.

[2] In 1965, the two scientists published their finding, and named a variety of the Gunflint flora.[3] This created an academic "stampede" to explore Precambrian microfossils from similar Proterozoic environments.

See also


  1. ^ Fralick, P., David, D. W. and Kissin, Stephen A. (2002). "The age of the Gunflint Formation, Ontario, Canada: single zircon U–Pb age determinations". Canadian Journal of Earth Sciences 39 (7): 1085–1091.  
  2. ^ Past lives: Chronicles of Canadian Paleontology
  3. ^ Barghoorn, E.S. and Tyler, S.A., 1965: Microorganisms from the Gunflint Chert. Science, vol. 147, p. 563-577.
  • Schopf, J.W., 1999: Cradle of Life: The Discovery of Earth's Earliest Fossils. Princeton University Press, 336 p. ISBN 0-691-00230-4
  • Superior type Banded Iron Formation
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