Imperial College London
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Professor Mark Rehkämper

Faculty of Engineering, Department of Earth Science & Engineering

Professor of Isotope Geochemistry
 
 
 
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Contact

 

markrehk Website

 
 
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Location

 

451Royal School of MinesSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Brett:2021:10.1016/j.gca.2021.02.035,
author = {Brett, EKA and Prytulak, J and Rehkämper, M and Hammond, SJ and Chauvel, C and Stracke, A and Willbold, M},
doi = {10.1016/j.gca.2021.02.035},
journal = {Geochimica et Cosmochimica Acta},
pages = {187--210},
title = {Thallium elemental and isotopic systematics in ocean island lavas},
url = {http://dx.doi.org/10.1016/j.gca.2021.02.035},
volume = {301},
year = {2021}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - The Earth’s mantle exhibits marked chemical heterogeneity. We provide an examination of thallium systematics in ocean island basalts (OIB): new high-precision trace element analyses, including Tl, and Tl isotopic compositions for 48 OIB spanning the entire range of observed Sr-Nd-Hf-Pb isotope ratios. All investigated OIB are characterised by ubiquitous Tl depletion requiring OIB mantle sources to have Tl concentrations as low as 0.2ng/g, which is an order of magnitude lower than estimates for the primitive mantle and similar to Tl concentrations inferred for the depleted mantle. The low Tl concentrations inferred for OIB mantle sources are interpreted to reflect near quantitative removal of Tl during subduction and inefficient Tl recycling into the deeper mantle. If true, the Tl isotopic composition of surface materials may not be readily translated to the mantle sources of OIB.The new OIB dataset shows a >10 ε-unit range in primary isotopic variation, from ε205Tl=−6.4 to +6.6. However, the majority of samples (32 of 48) are within uncertainty of mantle values (ε205Tl=−2±1), and show no co-variation with radiogenic isotopic composition. Notably, OIB with only minor Tl depletion (11 samples) have Tl isotopic compositions outside the mantle range. The Tl concentration contrast between the mantle and inputs such as sediments and altered basalt is so great that minor additions (<1% by mass) of high-Tl material will dominate the isotopic budget of a lava, with decoupling of Tl and radiogenic isotopic compositions as an expected result. Thallium isotopic compositions of OIB are therefore difficult to link directly to radiogenic isotope variations and the mantle components they may reflect. Indeed, if isotopically distinct Tl from altered oceanic crust and/or sediments were efficiently recycled into the mantle and sampled via OIB, more variation in the Tl isotopic composition of OIB would be expected than is ob
AU  - Brett,EKA
AU  - Prytulak,J
AU  - Rehkämper,M
AU  - Hammond,SJ
AU  - Chauvel,C
AU  - Stracke,A
AU  - Willbold,M
DO  - 10.1016/j.gca.2021.02.035
EP  - 210
PY  - 2021///
SN  - 0016-7037
SP  - 187
TI  - Thallium elemental and isotopic systematics in ocean island lavas
T2  - Geochimica et Cosmochimica Acta
UR  - http://dx.doi.org/10.1016/j.gca.2021.02.035
UR  - http://hdl.handle.net/10044/1/88608
VL  - 301
ER  -
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