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Zn isotope evidence for immediate resumption of primary productivity after snowball Earth

Kunzmann, Marcus and Halverson, Galen P. and Sossi, Paolo A. and Raub, Timothy D. and Payne, Justin L. and Kirby, Jason (2013) Zn isotope evidence for immediate resumption of primary productivity after snowball Earth. Geology, 41 (1). pp. 27-30. ISSN 0091-7613. https://resolver.caltech.edu/CaltechAUTHORS:20130206-133630513

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Abstract

The Ediacaran period began with the deglaciation of the ca. 635 Ma Marinoan snowball Earth and the deposition of cap dolostones on continental shelves worldwide during post-glacial sea-level rise. These carbonates sharply overlie glacial sediments deposited at low paleolatitudes and preserve negative carbon isotope excursions. The snowball Earth hypothesis invokes an almost complete cessation of primary productivity in the surface ocean. Because assimilatory uptake of Zn appears to fractionate its isotopes, Zn isotope ratios measured in carbonate precipitated in the surface ocean should track fluctuations in primary productivity. Here we report the first Zn isotopic data, together with carbon and oxygen isotopic profiles from a Neoproterozoic cap dolostone, the Nuccaleena Formation in the Flinders Ranges, South Australia. We interpret the Zn isotopic data in terms of a two-stage evolution of the deglacial ocean. Slightly ^(66)Zn-enriched values at the base of the cap dolostone indicate immediate resumption of the biological pump upon melting of the surface ocean, but this signal was diluted by intense surface runoff that drove δ^(66)Zn (^(66)Zn/^(64)Zn, versus the JMC Lyon reference) values down to the composition of continentally derived Zn. A subsequent rise in δ^(66)Zn records a vigorous increase in primary production and export from a nutrient-laden surface ocean.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1130/​G33422.1DOIUNSPECIFIED
http://geology.geoscienceworld.org/content/41/1/27.abstractPublisherUNSPECIFIED
Additional Information:© 2012 Geological Society of America. Received 19 March 2012. Revision received 21 June 2012. Accepted 25 June 2012. First published online October 2, 2012,
Issue or Number:1
Record Number:CaltechAUTHORS:20130206-133630513
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20130206-133630513
Official Citation:Marcus Kunzmann, Galen P. Halverson, Paolo A. Sossi, Timothy D. Raub, Justin L. Payne, and Jason Kirby Zn isotope evidence for immediate resumption of primary productivity after snowball Earth Geology, January 2013, v. 41, p. 27-30, first published online 2 October 2012, doi:10.1130/G33422.1
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:36795
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:07 Feb 2013 00:13
Last Modified:03 Oct 2019 04:41

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