Rare earth elements in conodont apatite: Seawater or pore-water signatures?

Julie Trotter, C.R. Barnes, A.D. Mccracken

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

© 2016 Elsevier B.V.Rare earth element (REE) compositions of Lower Palaeozoic conodont microfossils from different sites in Laurentia are presented and compared to modern pore-water REE compositions reported in the literature. These data are modelled to account for matrix-induced fractionation of REEs during uptake by apatite. The apatite-water partition co-efficients (Kd) for adsorption of REEs are applied to a range of modern pore-water compositions (i.e. Pore-waterN × Kd), the resultant data being similar to Palaeozoic conodont apatite compositions. Similar resemblances to modern pore-water REE compositions are shown by palaeofluids derived from conodonts using the inverse relationship in REE adsorption kinetics (i.e. Bioapatite/Kd), with rare low concentration samples yielding HREE-enriched patterns. These results clearly show the importance of matrix effects and hence the post-mortem physico-chemical processes by which elemental uptake occurs in fossil biogenic minerals, which are crucial to consider when interpreting geochemical signatures. Furthermore, the similarities between apatite REE compositions of conodonts and those derived from modern pore-waters challenge prior hypotheses of seawater REE evolution inferred directly from conodont apatite, and question the reliability of conodont apatite as archives of seawater REE chemistry. These outcomes likely have broader implications for fossil bioapatites in general given the physico-chemical processes occurring within marine sediments and the inherent behaviour of apatite-REE systematics.
Original languageEnglish
Pages (from-to)92-100
JournalPalaeogeography, Palaeoclimatology, Palaeoecology
Volume462
DOIs
Publication statusPublished - 2016

Fingerprint

rare earth elements
apatite
conodont
porewater
rare earth element
seawater
water
adsorption
chemical process
fossils
biogenic mineral
Paleozoic
microfossils
fossil
marine sediments
hydrochemistry
matrix
Laurentia
fractionation
microfossil

Cite this

@article{9728fc65d757429b953bc746a1165629,
title = "Rare earth elements in conodont apatite: Seawater or pore-water signatures?",
abstract = "{\circledC} 2016 Elsevier B.V.Rare earth element (REE) compositions of Lower Palaeozoic conodont microfossils from different sites in Laurentia are presented and compared to modern pore-water REE compositions reported in the literature. These data are modelled to account for matrix-induced fractionation of REEs during uptake by apatite. The apatite-water partition co-efficients (Kd) for adsorption of REEs are applied to a range of modern pore-water compositions (i.e. Pore-waterN × Kd), the resultant data being similar to Palaeozoic conodont apatite compositions. Similar resemblances to modern pore-water REE compositions are shown by palaeofluids derived from conodonts using the inverse relationship in REE adsorption kinetics (i.e. Bioapatite/Kd), with rare low concentration samples yielding HREE-enriched patterns. These results clearly show the importance of matrix effects and hence the post-mortem physico-chemical processes by which elemental uptake occurs in fossil biogenic minerals, which are crucial to consider when interpreting geochemical signatures. Furthermore, the similarities between apatite REE compositions of conodonts and those derived from modern pore-waters challenge prior hypotheses of seawater REE evolution inferred directly from conodont apatite, and question the reliability of conodont apatite as archives of seawater REE chemistry. These outcomes likely have broader implications for fossil bioapatites in general given the physico-chemical processes occurring within marine sediments and the inherent behaviour of apatite-REE systematics.",
author = "Julie Trotter and C.R. Barnes and A.D. Mccracken",
year = "2016",
doi = "10.1016/j.palaeo.2016.09.007",
language = "English",
volume = "462",
pages = "92--100",
journal = "Palaeogeography Palaeoclimatology Palaeoecology",
issn = "0031-0182",
publisher = "Elsevier",

}

Rare earth elements in conodont apatite: Seawater or pore-water signatures? / Trotter, Julie; Barnes, C.R.; Mccracken, A.D.

In: Palaeogeography, Palaeoclimatology, Palaeoecology, Vol. 462, 2016, p. 92-100.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Rare earth elements in conodont apatite: Seawater or pore-water signatures?

AU - Trotter, Julie

AU - Barnes, C.R.

AU - Mccracken, A.D.

PY - 2016

Y1 - 2016

N2 - © 2016 Elsevier B.V.Rare earth element (REE) compositions of Lower Palaeozoic conodont microfossils from different sites in Laurentia are presented and compared to modern pore-water REE compositions reported in the literature. These data are modelled to account for matrix-induced fractionation of REEs during uptake by apatite. The apatite-water partition co-efficients (Kd) for adsorption of REEs are applied to a range of modern pore-water compositions (i.e. Pore-waterN × Kd), the resultant data being similar to Palaeozoic conodont apatite compositions. Similar resemblances to modern pore-water REE compositions are shown by palaeofluids derived from conodonts using the inverse relationship in REE adsorption kinetics (i.e. Bioapatite/Kd), with rare low concentration samples yielding HREE-enriched patterns. These results clearly show the importance of matrix effects and hence the post-mortem physico-chemical processes by which elemental uptake occurs in fossil biogenic minerals, which are crucial to consider when interpreting geochemical signatures. Furthermore, the similarities between apatite REE compositions of conodonts and those derived from modern pore-waters challenge prior hypotheses of seawater REE evolution inferred directly from conodont apatite, and question the reliability of conodont apatite as archives of seawater REE chemistry. These outcomes likely have broader implications for fossil bioapatites in general given the physico-chemical processes occurring within marine sediments and the inherent behaviour of apatite-REE systematics.

AB - © 2016 Elsevier B.V.Rare earth element (REE) compositions of Lower Palaeozoic conodont microfossils from different sites in Laurentia are presented and compared to modern pore-water REE compositions reported in the literature. These data are modelled to account for matrix-induced fractionation of REEs during uptake by apatite. The apatite-water partition co-efficients (Kd) for adsorption of REEs are applied to a range of modern pore-water compositions (i.e. Pore-waterN × Kd), the resultant data being similar to Palaeozoic conodont apatite compositions. Similar resemblances to modern pore-water REE compositions are shown by palaeofluids derived from conodonts using the inverse relationship in REE adsorption kinetics (i.e. Bioapatite/Kd), with rare low concentration samples yielding HREE-enriched patterns. These results clearly show the importance of matrix effects and hence the post-mortem physico-chemical processes by which elemental uptake occurs in fossil biogenic minerals, which are crucial to consider when interpreting geochemical signatures. Furthermore, the similarities between apatite REE compositions of conodonts and those derived from modern pore-waters challenge prior hypotheses of seawater REE evolution inferred directly from conodont apatite, and question the reliability of conodont apatite as archives of seawater REE chemistry. These outcomes likely have broader implications for fossil bioapatites in general given the physico-chemical processes occurring within marine sediments and the inherent behaviour of apatite-REE systematics.

U2 - 10.1016/j.palaeo.2016.09.007

DO - 10.1016/j.palaeo.2016.09.007

M3 - Article

VL - 462

SP - 92

EP - 100

JO - Palaeogeography Palaeoclimatology Palaeoecology

JF - Palaeogeography Palaeoclimatology Palaeoecology

SN - 0031-0182

ER -