Investigations of the geochemistry of the rare earth elements in the exogenic cycle

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1989

OSTI ID:5369788

Olivarez, A M

This study investigates the REE geochemistry of three common sediment types (hydrothermal, eolian, and benthic layers) in order to understand their role in the exogenic cycle. The impact of seafloor hydrothermal activity upon the REE content of seawater was investigated by comparing REE/Fe ratios of hydrothermal sediments with end-member plume values. Hydrothermal activity results in a net depletion in REE's from seawater, primarily due to the large scavenging capacity of iron oxyhydroxides which precipitate from these solutions. The discrepancy between the predicted (positive) versus observed (negative) Eu anomaly of seawater was investigated by calculating REE scavenging indices for DSDP Site 598 hydrothermal precipitates is proportional to REE concentration in the fluid phase. The REE content of Lake Superior benthic layers are dominated by lithogenous sources, with minor contributions from the water column. The mechanism of REE removal from the water column may involve scavenging by Fe-rich phases. The eolian dust component of Pacific sediments is derived from two sources: the continental crust and oceanic crust, probably ash from circum-Pacific volcanism. The relative amount of the two end-members influences the median grain size. An eolian flux maximum exists between 35{degree}N and 42{degree}N in the northwest Pacific. This region also receives more eolian materials during glacial versus interglacial stages. A comparison of chemically treated versus untreated loess samples suggests that eolian dust is not a significant source of dissolved REE's to the oceans.

• Research Organization: Michigan Univ., Ann Arbor, MI (United States)
• OSTI ID: 5369788
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
ABSORPTION
CHEMICAL COMPOSITION
CHEMISTRY
COMPARATIVE EVALUATIONS
DESORPTION
ECOLOGICAL CONCENTRATION
ELEMENTS
ENVIRONMENTAL TRANSPORT
EVALUATION
GEOCHEMISTRY
GEOTHERMAL SYSTEMS
GREAT LAKES
HYDROGEN COMPOUNDS
HYDROTHERMAL ALTERATION
HYDROTHERMAL SYSTEMS
IRON COMPOUNDS
LAKE SUPERIOR
LAKES
MASS TRANSFER
MATTER
METALS
ORGANIC MATTER
OXYGEN COMPOUNDS
RARE EARTHS
SEAWATER
SEDIMENTS
SINKS
SURFACE WATERS
TRANSITION ELEMENT COMPOUNDS
WATER
WATER CHEMISTRY