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Snowball Earth ocean chemistry driven by extensive ridge volcanism during Rodinia breakup

Snowball Earth ocean chemistry driven by extensive ridge volcanism during Rodinia breakup
Snowball Earth ocean chemistry driven by extensive ridge volcanism during Rodinia breakup
During Neoproterozoic Snowball Earth glaciations, the oceans gained massive amounts of alkalinity, culminating in the deposition of massive cap carbonates on deglaciation. Changes in terrestrial runoff associated with both breakup of the Rodinia supercontinent and deglaciation can explain some, but not all of the requisite changes in ocean chemistry. Submarine volcanism along shallow ridges formed during supercontinent breakup results in the formation of large volumes of glassy hyaloclastite, which readily alters to palagonite. Here we estimate fluxes of calcium, magnesium, phosphorus, silica and bicarbonate associated with these shallow-ridge processes, and argue that extensive submarine volcanism during the breakup of Rodinia made an important contribution to changes in ocean chemistry during Snowball Earth glaciations. We use Monte Carlo simulations to show that widespread hyaloclastite alteration under near-global sea-ice cover could lead to Ca2+ and Mg2+ supersaturation over the course of the glaciation that is sufficient to explain the volume of cap carbonates deposited. Furthermore, our conservative estimates of phosphorus release are sufficient to explain the observed P:Fe ratios in sedimentary iron formations from this time. This large phosphorus release may have fuelled primary productivity, which in turn would have contributed to atmospheric O2 rises that followed Snowball Earth episodes.
1752-0894
242-248
Gernon, T.M.
658041a0-fdd1-4516-85f4-98895a39235e
Hincks, T.K.
d7f00c82-f34b-4db0-a6a6-ff5bae3cdf57
Tyrrell, T.
6808411d-c9cf-47a3-88b6-c7c294f2d114
Rohling, E.J.
a2a27ef2-fcce-4c71-907b-e692b5ecc685
Palmer, M.R.
d2e60e81-5d6e-4ddb-a243-602537286080
Gernon, T.M.
658041a0-fdd1-4516-85f4-98895a39235e
Hincks, T.K.
d7f00c82-f34b-4db0-a6a6-ff5bae3cdf57
Tyrrell, T.
6808411d-c9cf-47a3-88b6-c7c294f2d114
Rohling, E.J.
a2a27ef2-fcce-4c71-907b-e692b5ecc685
Palmer, M.R.
d2e60e81-5d6e-4ddb-a243-602537286080

Gernon, T.M., Hincks, T.K., Tyrrell, T., Rohling, E.J. and Palmer, M.R. (2016) Snowball Earth ocean chemistry driven by extensive ridge volcanism during Rodinia breakup. Nature Geoscience, 9, 242-248. (doi:10.1038/ngeo2632).

Record type: Article

Abstract

During Neoproterozoic Snowball Earth glaciations, the oceans gained massive amounts of alkalinity, culminating in the deposition of massive cap carbonates on deglaciation. Changes in terrestrial runoff associated with both breakup of the Rodinia supercontinent and deglaciation can explain some, but not all of the requisite changes in ocean chemistry. Submarine volcanism along shallow ridges formed during supercontinent breakup results in the formation of large volumes of glassy hyaloclastite, which readily alters to palagonite. Here we estimate fluxes of calcium, magnesium, phosphorus, silica and bicarbonate associated with these shallow-ridge processes, and argue that extensive submarine volcanism during the breakup of Rodinia made an important contribution to changes in ocean chemistry during Snowball Earth glaciations. We use Monte Carlo simulations to show that widespread hyaloclastite alteration under near-global sea-ice cover could lead to Ca2+ and Mg2+ supersaturation over the course of the glaciation that is sufficient to explain the volume of cap carbonates deposited. Furthermore, our conservative estimates of phosphorus release are sufficient to explain the observed P:Fe ratios in sedimentary iron formations from this time. This large phosphorus release may have fuelled primary productivity, which in turn would have contributed to atmospheric O2 rises that followed Snowball Earth episodes.

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Accepted/In Press date: 10 December 2015
Published date: 18 January 2016
Organisations: Geology & Geophysics, Geochemistry, Ocean and Earth Science, Paleooceanography & Palaeoclimate

Identifiers

Local EPrints ID: 386413
URI: https://eprints.soton.ac.uk/id/eprint/386413
ISSN: 1752-0894
PURE UUID: 7ae2edb6-b84c-48e5-ad62-029d556c048f
ORCID for T. Tyrrell: ORCID iD orcid.org/0000-0002-1002-1716
ORCID for E.J. Rohling: ORCID iD orcid.org/0000-0001-5349-2158

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Date deposited: 25 Jan 2016 13:41
Last modified: 15 Aug 2019 00:54

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Contributors

Author: T.M. Gernon
Author: T.K. Hincks
Author: T. Tyrrell ORCID iD
Author: E.J. Rohling ORCID iD
Author: M.R. Palmer

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