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Rare earth element deposition in pelagic sediment at the Cenomanian‐Turonian Boundary, Exmouth Plateau
Author(s) -
Dickens Gerald R.,
Owen Robert M.
Publication year - 1995
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/94gl03047
Subject(s) - geology , authigenic , pelagic sediment , rare earth element , sediment , continental margin , fluvial , deposition (geology) , pelagic zone , trace element , continental shelf , geochemistry , oceanography , seawater , mineralogy , rare earth , paleontology , structural basin , tectonics
ODP Site 762 (eastern Indian Ocean) includes a section of sediment that spans the Cenomanian‐Turonian Boundary (CTB) and was deposited along a continental margin during a period of widespread oceanic O 2 deficiency. The rare earth element (REE) content of pre‐ and post‐boundary sediment is similar to that of present‐day continental slope material deposited in well‐oxygenated seawater, whereas the CTB section is characterized by significantly depleted REE abundances, a bulk Ce anomaly that increases to maximum of 1.0, and a REE pattern that resembles that of present‐day fluvial material. We suggest the change in REE patterns reflects release of scavenged REEs upon reductive dissolution of authigenic Fe‐Mn oxyhydroxides, such that sediment deposited during the CTB is dominated by the lithogenous REE fraction. These results are consistent with recent models concerning pervasive fractionation of Mn and Fe and redirection of Mn in pelagic CTB waters.