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Title: Trace elements in marine biogenic carbonates : analysis and application to past ocean chemistry
Author: Greaves, Mervyn John
ISNI:       0000 0004 2726 5607
Awarding Body: University of Southampton
Current Institution: University of Southampton
Date of Award: 2008
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Trace elements in marine biogenic carbonates may be used as proxies for past ocean chemistry provided that there is an established relationship between the trace element proxy and a parameter of interest, this relationship is preserved within biogenic carbonate, and the trace element can be determined sufficiently accurately. Successful application of any trace element proxy requires both development of the analytical methodology to ensure accurate data with the necessary sensitivity, and an understanding of the relationship between proxy and seawater chemistry. Herein I develop methods for the determination of Mg/Ca, Sr/Ca and Cd/Ca in planktonic foraminiferal calcite, using inductively coupled plasma optical emission spectrophotometry and isotope dilution thermal ionisation mass spectrometry, and propose a potential reference material for Mg/Ca in foraminiferal calcite. The developed techniques are applied to an investigation of the Mg/Ca temperature proxy over Chatham Rise in the Southwest Pacific Ocean and a calibration study of the partition coefficient, DCd, for cadmium incorporation into planktonic foraminifera. Comparisons of planktonic foraminiferal Mg/Ca, shell weight and oxygen isotope records from sites north and south of the Subtropical Front on Chatham Rise, demonstrate the effects of hydrography, foraminiferal habitat and dissolution as controls on Mg/Ca. Determinations of Cd/Ca in seven species of planktonic foraminifera confirm that the dominant controls on Cd/Ca are foraminiferal habitat and hydrography, with only a minor influence of post depositional dissolution. The major uncertainty in determination of DCd from core top samples comes from uncertainty in estimation of the depth distribution and seasons of calcification of planktonic foraminifera.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QD Chemistry ; GC Oceanography