Sheet-crack cements in Marinoan (635 Ma) cap dolostones as regional benchmarks of vanishing ice-sheets.

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Sheet-crack cements in Marinoan (635 Ma) cap dolostones as regional benchmarks of vanishing ice-sheets.

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Title: Sheet-crack cements in Marinoan (635 Ma) cap dolostones as regional benchmarks of vanishing ice-sheets.
Author: Macdonald, Francis Alexander
Citation: Hoffman, Paul F., and Macdonald, Francis A. Sheet-crack cements in Marinoan (635 Ma) cap dolostones as regional benchmarks of vanishing ice-sheets. Earth and Planetary Science Letters 300 (2010) 374-384.
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Abstract: Sheet-crack cements and coextensive intrastratal folds and breccias occur in a stratigraphically controlled, meter-thick zone, near the base of Marinoan (635 Ma) cap dolostones in slope settings. We demonstrate that sheet-crack cements on the margins of the Congo and Kalahari cratons are localized at a turbidite-to-grainstone transition, which records a transient fall in relative sea-level, preceding the larger glacioeustatic transgression. Sheet-cracks opened vertically, implying that pore-fluid pressure exceeded lithostatic pressure. When the margin of an ice-sheet retreats from a coast, a net fall in sea-level occurs in the vicinity, because of the weakened gravitational attraction between the ice-sheet and the nearby ocean. Augmented by glacioisostatic adjustment (postglacial rebound), the early regional fall in relative sea-level can mask the simultaneous rise in global mean sea-level caused by the addition of meltwater. We propose that sheet-cracks and related structures in Marinoan cap dolostones manifest pore-fluid overpressures resulting from rapid sea-level falls in the vicinity of vanishing ice-sheets.
Published Version: doi:10.1016/j.epsl.2010.10.027
Terms of Use: This article is made available under the terms and conditions applicable to Other Posted Material, as set forth at http://nrs.harvard.edu/urn-3:HUL.InstRepos:dash.current.terms-of-use#LAA
Citable link to this page: http://nrs.harvard.edu/urn-3:HUL.InstRepos:8141467

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  • FAS Scholarly Articles [7220]
    Peer reviewed scholarly articles from the Faculty of Arts and Sciences of Harvard University
 
 

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