Comment on “What do we know about the evolution of Mg to Ca ratios in seawater?” by Wally Broecker and Jimin Yu
Comment on “What do we know about the evolution of Mg to Ca ratios in seawater?” by Wally Broecker and Jimin Yu
A record of the Mg/Ca ratio of ancient seawater is essential to understand variations in the major geological processes that control ocean chemistry and for estimating past ocean temperatures. A recent contribution by Broecker and Yu (2011) regarding past seawater Mg/Ca provides an unbalanced assessment of the uncertainties and key assumptions of the methodologies considered. It misrepresents aspects of a new method to estimate past ocean Mg/Ca proposed by Coggon et al. (2010); here we provide clarification of that approach. We estimate the accuracy and precision of seawater Mg/Ca estimates derived from planktonic foraminifera test calcite, the preferred approach of Broecker and Yu. These are shown to be consistent with other records that suggest major changes in seawater cation chemistry. An explanation of how major changes in the Mg/Ca of seawater might occur is beyond the scope of this comment.
PA3224
Coggon, Rosalind M.
09488aad-f9e1-47b6-9c62-1da33541b4a4
Teagle, Damon A.H.
396539c5-acbe-4dfa-bb9b-94af878fe286
Dunkley Jones, Tom
f4025985-97e2-46c7-bff5-aaa45f9f8289
2011
Coggon, Rosalind M.
09488aad-f9e1-47b6-9c62-1da33541b4a4
Teagle, Damon A.H.
396539c5-acbe-4dfa-bb9b-94af878fe286
Dunkley Jones, Tom
f4025985-97e2-46c7-bff5-aaa45f9f8289
Coggon, Rosalind M., Teagle, Damon A.H. and Dunkley Jones, Tom
(2011)
Comment on “What do we know about the evolution of Mg to Ca ratios in seawater?” by Wally Broecker and Jimin Yu.
Paleoceanography, 26 (3), .
(doi:10.1029/2011PA002186).
Abstract
A record of the Mg/Ca ratio of ancient seawater is essential to understand variations in the major geological processes that control ocean chemistry and for estimating past ocean temperatures. A recent contribution by Broecker and Yu (2011) regarding past seawater Mg/Ca provides an unbalanced assessment of the uncertainties and key assumptions of the methodologies considered. It misrepresents aspects of a new method to estimate past ocean Mg/Ca proposed by Coggon et al. (2010); here we provide clarification of that approach. We estimate the accuracy and precision of seawater Mg/Ca estimates derived from planktonic foraminifera test calcite, the preferred approach of Broecker and Yu. These are shown to be consistent with other records that suggest major changes in seawater cation chemistry. An explanation of how major changes in the Mg/Ca of seawater might occur is beyond the scope of this comment.
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Published date: 2011
Organisations:
Ocean and Earth Science, Geochemistry
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Local EPrints ID: 201075
URI: http://eprints.soton.ac.uk/id/eprint/201075
ISSN: 0883-8305
PURE UUID: 364b3623-43a8-4f28-84d1-0765e4efa84b
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Date deposited: 25 Oct 2011 09:40
Last modified: 15 Mar 2024 03:45
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Tom Dunkley Jones
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