Sr isotopic variation in single conodont elements: Implications for defining the Sr seawater curve

Julie A. Trotter, Michael J. Korsch, Robert S. Nicoll, David J. Whitford

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Sr isotopic compositions of single conodont elements were measured to investigate the potential usefulness of conodonts in defining the Sr isotope seawater curve. Analysed elements had very low colour alteration indices (CAI = 1) and were of the coniform species Drepanodus arcuatus (Pander, 1856), sampled from the Early Ordovician (early Bendigonian, ~490 - 492Ma) Emanuel Formation in the Canning Basin of Western Australia. 87Sr/86Sr ratios measured from single whole conodont elements were compared to those from mechanically separated cusp tissue and from the element base with attachment cone, showing significant isotopic heterogeneity within single elements. Cusps are characterised by significantly lower 87SR/86Sr ratios (0.708949 - 0.709056) than their associated base and attachment cone (0.709503 - 0.709829), and are well within the boundaries of the seawater curve. Single whole elements have 87Sr/86Sr ratios (0.709097 - 0.709282) intermediate between cusp and basal tissue. Host-rock limestone from the same horizon yielded high 87Sr/86Sr ratios (0.709368, 0.709454). A few small, thin-shelled articulate brachiopods recovered from elsewhere in the section have also suffered significant diagenetic alteration; the 87Sr/86Sr measurements of secondary shell material range from 0.709027 to 0.709430. These results indicate both carbonate and phosphate components have experienced significant diagenetic alteration, and that basal tissue appears to be a major source of secondary Sr in D. arcuatus. Despite the isotopic heterogeneity of conodont apatite, preliminary results suggest that the lowest, and perhaps primary, 87Sr/86Sr ratio (0.708750) is retained near the 'core' of cusp tissue, at the growth axis.

Original languageEnglish
Pages (from-to)507-514
Number of pages8
JournalBollettino della Societa Paleontologica Italiana
Volume37
Issue number2-3
Publication statusPublished - 1 Dec 1998
Externally publishedYes

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conodont
seawater
brachiopod
host rock
apatite
Ordovician
isotopic composition
phosphate
limestone
isotope
shell
carbonate
tissue
basin

Cite this

Trotter, Julie A. ; Korsch, Michael J. ; Nicoll, Robert S. ; Whitford, David J. / Sr isotopic variation in single conodont elements : Implications for defining the Sr seawater curve. In: Bollettino della Societa Paleontologica Italiana. 1998 ; Vol. 37, No. 2-3. pp. 507-514.
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Sr isotopic variation in single conodont elements : Implications for defining the Sr seawater curve. / Trotter, Julie A.; Korsch, Michael J.; Nicoll, Robert S.; Whitford, David J.

In: Bollettino della Societa Paleontologica Italiana, Vol. 37, No. 2-3, 01.12.1998, p. 507-514.

Research output: Contribution to journalArticle

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T1 - Sr isotopic variation in single conodont elements

T2 - Implications for defining the Sr seawater curve

AU - Trotter, Julie A.

AU - Korsch, Michael J.

AU - Nicoll, Robert S.

AU - Whitford, David J.

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M3 - Article

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SP - 507

EP - 514

JO - Bollettino della Societa Paleontologica Italiana

JF - Bollettino della Societa Paleontologica Italiana

SN - 0375-7633

IS - 2-3

ER -