Comment on “What do we know about the evolution of Mg to Ca ratios in seawater?” by Wally Broecker and Jimin Yu


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), PA3224. (doi:10.1029/2011PA002186).

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Description/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.

Item Type: Article
ISSNs: 0883-8305 (print)
1944-9186 (electronic)
Subjects: G Geography. Anthropology. Recreation > GC Oceanography
Q Science > QD Chemistry
Q Science > QE Geology
Divisions: Faculty of Natural and Environmental Sciences > Ocean and Earth Science > Geochemistry
Faculty of Natural and Environmental Sciences > Ocean and Earth Science
ePrint ID: 201075
Date Deposited: 25 Oct 2011 09:40
Last Modified: 14 Apr 2014 11:06
Research Funder: NERC
Projects:
Ocean Basement Calcium Carbonate Veins as Recorders of Past Ocean Chemistry and the Global Carbon Cycle
Funded by: NERC (NE/I006311/1)
Led by: Damon Andrew Teagle
1 August 2010 to 31 January 2014
URI: http://eprints.soton.ac.uk/id/eprint/201075

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