Influence of Sediment Cycling on the Rare-Earth Element Geochemistry of Fluvial Deposits (Caculuvar–Mucope, Cunene River Basin, Angola)

The rare-earth element (REE) geochemistry of sedimentary deposits has been used in provenance investigations despite the transformation that this group of elements may suffer during a depositional cycle. In the present investigation, we used the geochemistry and XRD mineralogy of a set of sand and m...

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Bibliographic Details
Published in:Geosciences (Basel) 2021-09, Vol.11 (9), p.384
Main Authors: Cruz, Armanda, Dinis, Pedro A., Gomes, Alberto, Leite, Paula
Format: Article
Language:English
Subjects:
Basins
Cerium
Chemical elements
Crystalline rocks
Cunene River Basin
Depletion
Deposits
Dilution
Drainage basins
Earth science
exogenous compositional transformations
Fluvial deposits
fluvial sediments
Geochemistry
Geology
Igneous rocks
Lithology
Mineralogy
Mud
Rare earth elements
recognition of primary sources
River basins
Rivers
Sand
Sediment
Sediment deposits
Sediments
Weathering
Yttrium
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Summary:The rare-earth element (REE) geochemistry of sedimentary deposits has been used in provenance investigations despite the transformation that this group of elements may suffer during a depositional cycle. In the present investigation, we used the geochemistry and XRD mineralogy of a set of sand and mud fluvial deposits to evaluate the ability of REE parameters in provenance tracing, and the changes in REE geochemistry associated with weathering and sorting. The analyzed deposits were generated in a subtropical drainage basin where mafic and felsic units are evenly represented, and these crystalline rocks are covered by sedimentary successions in a wide portion of the basin. A few element ratios appear to hold robust information about primary sources (Eu/Y, Eu/Eu*, LaN/YbN, LaN/SmN, and GdN/YbN), and the provenance signal is best preserved in sand than in mud deposits. Sediment cycles, however, change the REE geochemistry, affecting mud and sand deposits differently. They are responsible for significant REE depletion through quartz dilution in sands and may promote discernible changes in REE patterns in muds (e.g., increase in Ce content and some light REE depletion relative to heavy REE).
ISSN:2076-3263
2076-3263
DOI:10.3390/geosciences11090384