Bulletin of Geosciences · 2012 · 13 citations · 43 references
Natural SciencesEarth SciencesGeologyGeochemistryPetrologyStratigraphyMineral GeochemistryPetrographySilicate MineralsVolcanic AshVolcanic Ash StratigraphyVolcanic GeochemistryAsh Bed StratigraphyAuthigenic MineralsMagma Source CharacterizationMagma Source GeochemistryMagma Source RegionsStrontium Isotope AnalysisVolcanic Ash Bed CorrelationVolcanic Ash Geochemistry
In three drill cores in Latvia and Lithuania a thin (1 cm thick) altered volcanic ash bed with high concentrations of phosphorus (up to 3%), cerium (1%), lanthanum (0.5%) and strontium (2.5%), has been found close to the Aeronian/Telychian boundary (Llandovery, Silurian, ca 438 Ma). Small, millimetre-thick lenses within the ash bed contain up to 12% P and Sr, up to 6% Ce and 3% La. These elements occur as a solid solution of goyazite-florencite mineral. Additionally, authigenic K-feldspar and kaolinite occur in this ash bed. The high concentrations of REE elements, strontium and phosphorus suggest a carbonatite source magma, but the strontium isotope ratio contradicts that origin. Such a unique composition in a volcanic ash layer is a good basis for using it as a marker horizon for correlation of sections.
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Geochemistry and mineralogy of rare earth elements
S. R. Taylor · Geochimica et Cosmochimica Acta · 1990 · 522 citations