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<article language="en">
	<journal>
		<journal_title>Biogeosciences Discussions</journal_title>
		<journal_url>www.biogeosciences-discuss.net</journal_url>
		<issn>1810-6277</issn>
		<eissn>1810-6285</eissn>
		<volume_number>6</volume_number>
		<issue_number>1</issue_number>
		<publication_year>2009</publication_year>
	</journal>
	<doi>10.5194/bgd-6-1267-2009</doi>
	<article_url>http://www.biogeosciences-discuss.net/6/1267/2009/</article_url>
	<abstract_html>http://www.biogeosciences-discuss.net/6/1267/2009/bgd-6-1267-2009.html</abstract_html>
	<fulltext_pdf>http://www.biogeosciences-discuss.net/6/1267/2009/bgd-6-1267-2009.pdf</fulltext_pdf>
	<start_page>1267</start_page>
	<end_page>1316</end_page>
	<publication_date>2009-01-23</publication_date>
	<article_title content_type="html">Ion microprobe assessment of the heterogeneity of Mg/Ca, Sr/Ca and Mn/Ca ratios in &lt;i&gt;Pecten maximus&lt;/i&gt; and &lt;i&gt;Mytilus edulis&lt;/i&gt; (bivalvia) shell calcite precipitated at constant temperature</article_title>
	<authors>
		<author numeration="1" affiliations="1,2">
			<name>P. S. Freitas</name>
			<email>pedro.freitas@ineti.pt</email>
		</author>
		<author numeration="2" affiliations="1">
			<name>L. J. Clarke</name>
		</author>
		<author numeration="3" affiliations="1">
			<name>H. Kennedy</name>
		</author>
		<author numeration="4" affiliations="1">
			<name>C. A. Richardson</name>
		</author>
	</authors>
	<affiliations>
		<affiliation numeration="1" content_type="html">School of Ocean Sciences, College of Natural Sciences, Bangor University, Askew Street, Menai Bridge, Isle of Anglesey, LL59 5AB, UK</affiliation>
		<affiliation numeration="2" content_type="html">Departamento de Geologia Marinha, Laboratório Nacional de Energia e Geologia, Estrada da Portela &amp;ndash; Zambujal, 2721-866 Alfragide, Portugal</affiliation>
	</affiliations>
	<abstract content_type="html">Small-scale heterogeneity of biogenic carbonate elemental composition can be
a significant source of error in the accurate use of element/Ca ratios as
geochemical proxies. In this study ion microprobe (SIMS) profiles showed
significant small-scale variability of Mg/Ca, Sr/Ca and Mn/Ca ratios in new
shell calcite of the marine bivalves &lt;i&gt;P. maximus&lt;/i&gt; and &lt;i&gt;Mytilus edulis&lt;/i&gt; that was precipitated during a
constant-temperature culturing experiment. Elevated Mg/Ca, Sr/Ca and Mn/Ca
ratios were found to be associated with the deposition of elaborate shell
features, i.e. a shell surface stria in &lt;i&gt;P. maximus&lt;/i&gt; and surface shell disturbance marks
in both species, the latter a common occurrence in bivalve shells. In both
species the observed small-scale elemental heterogeneity most likely was not
controlled by variable transport of ions to the extra-pallial fluid, but by
factors such as shell Mg content influencing Sr and Mn heterogeneity, the
influence of shell organic content and/or conditions at the shell
crystal-solution interface. Invariant Mg/Ca ratios observed in the mid and
innermost regions of the &lt;i&gt;P. maximus&lt;/i&gt; shell suggests a potential application as a
palaeotemperature proxy.</abstract>
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</article>
