Was the deposition of large Precambrian iron formations linked to major marine transgressions?

Title:
Was the deposition of large Precambrian iron formations linked to major marine transgressions?
Authors:
Simonson, Bruce M.; Hassler, Scott W.
Abstract:
Geochemical evidence suggests the iron- and silica-rich precipitates that compose large Neoarchean and Paleoproterozoic iron formations formed along a chemocline between iron-rich deep water and iron-poor surface water. Sedimento-logical evidence indicates many large iron formations accumulated in marine shelf environments during major transgressions. We suggest this occurred because the chemocline could only impinge on continental shelves during times of sea-level rise or highstand. On the other hand, the stratigraphic record indicates that deposition of iron formations ceased during regressions in some basins and transgressions in others. To explain this, we propose that iron concentrations in the Precambrian ocean were greatest at mid-water depths in a zone on the order of 100 m thick. Radiometric age dates from the Hamersley Basin of Western Australia suggest major iron-formation deposition had a periodicity of ca. 20 to 125 m.y., close to second-order cycles in Phanerozoic sea level driven by long-term tectonic processes such as changes in the rate of crustal production. While the time scale of the deposition of large iron formations appears to be too long-for glacioeustatic or Milankovitch forcing, smaller-scale cycles exist within many iron formations which could reflect the latter.
Citation:
Simonson, B.M. and S.W. Hassler. 1996. "Was the deposition of large Precambrian iron formations linked to major marine transgressions?" Journal of Geology 104(6): 665-676.
Publisher:
University of Chicago Press
DATE ISSUED:
1996-11
Department:
Geology
Type:
article
PUBLISHED VERSION:
10.1086/629861
PERMANENT LINK:
http://hdl.handle.net/11282/309657

Full metadata record

DC FieldValue Language
dc.contributor.authorSimonson, Bruce M.en_US
dc.contributor.authorHassler, Scott W.en_US
dc.date.accessioned2013-12-23T16:14:22Zen
dc.date.available2013-12-23T16:14:22Zen
dc.date.issued1996-11en
dc.identifier.citationSimonson, B.M. and S.W. Hassler. 1996. "Was the deposition of large Precambrian iron formations linked to major marine transgressions?" Journal of Geology 104(6): 665-676.en_US
dc.identifier.issn0022-1376en_US
dc.identifier.urihttp://hdl.handle.net/11282/309657en
dc.description.abstractGeochemical evidence suggests the iron- and silica-rich precipitates that compose large Neoarchean and Paleoproterozoic iron formations formed along a chemocline between iron-rich deep water and iron-poor surface water. Sedimento-logical evidence indicates many large iron formations accumulated in marine shelf environments during major transgressions. We suggest this occurred because the chemocline could only impinge on continental shelves during times of sea-level rise or highstand. On the other hand, the stratigraphic record indicates that deposition of iron formations ceased during regressions in some basins and transgressions in others. To explain this, we propose that iron concentrations in the Precambrian ocean were greatest at mid-water depths in a zone on the order of 100 m thick. Radiometric age dates from the Hamersley Basin of Western Australia suggest major iron-formation deposition had a periodicity of ca. 20 to 125 m.y., close to second-order cycles in Phanerozoic sea level driven by long-term tectonic processes such as changes in the rate of crustal production. While the time scale of the deposition of large iron formations appears to be too long-for glacioeustatic or Milankovitch forcing, smaller-scale cycles exist within many iron formations which could reflect the latter.en_US
dc.language.isoen_USen_US
dc.publisherUniversity of Chicago Pressen_US
dc.identifier.doi10.1086/629861en_US
dc.subject.departmentGeologyen_US
dc.titleWas the deposition of large Precambrian iron formations linked to major marine transgressions?en_US
dc.typearticleen_US
dc.identifier.journalJournal of Geologyen_US
dc.identifier.volume104en_US
dc.identifier.issue6en_US
dc.identifier.startpage665en_US
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