ABSTRACT

Under the highly stagnant condition at the Cariaco Trench, the lanthanide tetrad effect takes place abruptly within an extremely narrow depth range. The lanthanide tetrad effect maximum at the Cariaco Trench is observed at 256 m coinciding with its oxic/anoxic interface at 280 m. It is also interesting that the maximum value of the lanthanide tetrad effect at this trench is substantially the same as that in ordinary open ocean.