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Late Pliocene and Early Pleistocene Variability of the REE and Nd Isotope Composition of Caribbean Bottom Water: A Record of Changes in Sea Level and Terrestrial Inputs During the Final Stages of Central American Seaway Closure
Author(s) -
Osborne Anne H.,
Hathorne Ed C.,
Böning Philipp,
Groeneveld Jeroen,
Pahnke Katharina,
Frank Martin
Publication year - 2019
Publication title -
paleoceanography and paleoclimatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.927
H-Index - 127
eISSN - 2572-4525
pISSN - 2572-4517
DOI - 10.1029/2019pa003654
Subject(s) - geology , authigenic , terrigenous sediment , seawater , pleistocene , oceanography , glacial period , quaternary , foraminifera , early pleistocene , deep sea , isotopes of oxygen , paleontology , diagenesis , sedimentary rock , geochemistry , benthic zone
The isotopic composition of neodymium dissolved in seawater consists of a distal, advected component that reflects water mass mixing and circulation but near land can also contain a large local component originating from terrestrial sources such as aeolian or fluvial material. In order to use Nd isotopes to reconstruct paleocirculation, it is important to detect any local influences on the seawater signal recorded in deep sea sediments. Here we present rare earth element (REE) and Nd isotope (ε Nd ) records from the deep Caribbean for two well‐studied time intervals in the Late Pliocene and Early Pleistocene. We measured trace element and REE compositions of weakly cleaned foraminifera to investigate if the Nd isotope signal from the same samples contained a local component. We find distinct changes in REE compositions across glaciations that are consistent with increases in the supply of local terrestrial material to the basin likely the results of glacially driven changes in sea level. Despite these larger terrestrial inputs, the Ce anomaly (Ce/Ce*) became more pronounced during glaciations indicating a better deep Caribbean ventilation. Short negative Nd isotope excursions occurred during three of the four studied glaciations, independently of any other proxy indicators for changes in ocean circulation suggesting that inputs from local terrigenous sources of Nd controlled the signal. We recommend that studies that aim to use ε Nd as a paleocirculation tracer routinely measure REE compositions of the authigenic phase to identify any possible terrestrial influence on the signal.