The potential of sedimentary foraminiferal rare earth element patterns to trace water masses in the past
File(s)
Author(s)
Type
Journal Article
Abstract
Dissolved rare earth element (REE) concentration data from intermediate and deep seawater form an array characterized by higher middle‐REE enrichments (MREE/MREE*) in the North Atlantic and a progressive increase in heavy‐to‐light REE ratios (HREE/LREE) as water masses age. The REEs in foraminifera are fractionated toward higher MREE/MREE* and lower HREE/LREE relative to seawater. Calculations based on a scavenging model show that the REE patterns in uncleaned core‐top foraminifera resemble those adsorbed onto calcite, particulate organic material, and hydrous ferric oxides but the full extent of the REE fractionation measured in foraminifera was not reproduced by the model. However, differences in the HREE/LREE and MREE/MREE* ratios and the cerium anomaly between ocean basins are preserved and are in agreement with the seawater REE distribution. Under oxic conditions, the HREE/LREE and MREE/MREE* compositions of uncleaned foraminifera at the sediment/seawater boundary are preserved during burial but the cerium anomaly is sensitive to burial depth. In suboxic sedimentary environments, all uncleaned foraminiferal REE concentrations are elevated relative to core‐top values indicating addition of REEs from pore waters. The HREE/LREE ratio is highest when sedimentation rates were greatest and when high Fe/Ca ratios in the uncleaned foraminifera indicate that Fe was mobile. In sediments that have not experienced suboxic conditions during burial, uncleaned foraminifera preserve the seawater signal taken up at the sediment/seawater interface and are therefore suggested to be a suitable archive of changes in the REE signal of past bottom waters.
Date Issued
2017-04-01
Date Acceptance
2017-03-14
Citation
Geochemistry, Geophysics, Geosystems, 2017, 18 (4), pp.1550-1568
ISSN
1525-2027
Publisher
American Geophysical Union
Start Page
1550
End Page
1568
Journal / Book Title
Geochemistry, Geophysics, Geosystems
Volume
18
Issue
4
Copyright Statement
© 2017. American Geophysical Union. All Rights Reserved. This is the accepted version of the following article, which has been published in final form at https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2016GC006782
Identifier
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000403478500014&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
Subjects
Science & Technology
Physical Sciences
Geochemistry & Geophysics
ND ISOTOPIC COMPOSITION
EASTERN INDIAN-OCEAN
DEEP-SEA SEDIMENTS
M NACL SOLUTIONS
NEODYMIUM ISOTOPES
SOUTH ATLANTIC
AUTHIGENIC PHASES
CERIUM OXIDATION
MARINE-SEDIMENTS
YREE SORPTION
Publication Status
Published
Date Publish Online
2017-03-17