TRACE ELEMENT DISTRIBUTION IN SEDIMENTS OF THE MID-ATLANTIC RIDGE.
MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH AND PLANETARY SCIENCES
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Several sediments from the flank of the Mid-Atlantic Ridge were analyzed for trace elements by neutron activation analysis. It was found that high concentrations of iron, cobalt, manganese and strontium are associated as coatings on the 37-73 micron size fraction of foraminiferal calcite. The metals appear to be derived from the decomposition of clay minerals associated with the carbonate. Strontium appears to be a contaminant introduced by partial solution of a non-carbonate mineral. Rare earth analysis indicated that an established rare earth distribution is stable during the conversion of palagonite to greenstone and during the conversion of iron-rich chlorite to magnesium-rich chlorite. The fine chlorite in the sediment appears to be local in origin while the montmorillonite appears continental. Amorphous sediments from the immediate vicinity appear to be a product of a local ash flow. They were all enriched in rare earths compared to local basalts. This enrichment is probably due to an enrichment of rare earths in the parent magma compared to basalts but may in part represent the result of selective complexation of rare earths by anions in sea water. Author
- Physical and Dynamic Oceanography
- Geology, Geochemistry and Mineralogy