Sr-Nd isotope signatures of surficial sediments from the Portuguese continental shelf
2013
This study focus on the Sr-Nd isotope signatures of detrital and carbonate fractions of seven samples from
surficial sediments deposited in the Portuguese continental shelf. 87Sr/86Sr and 143Nd/144Nd isotope compositions of the
lithic component are used to constrain potential endmember contributions and determine sediment provenance. The
87Sr/86Sr ratios measured in the acid leachates of the seven sediment samples (carbonate fraction) lie within the range
0.7088 - 0.7092, close to the value for modern seawater (0.7091 - 0.7092), suggesting a dominant biogenic origin for
this component. In contrast, the Sr isotope signatures for acid-leached silicate residues (lithic fraction) from the same
samples are widely variable (87Sr/86Sr = 0.7179 to 0.7346) reflecting the input of terrigenous particles from three
distinct sources (northern Iberian Variscan crust, southern Iberian Variscan crust and North African aerosols). The
narrow range of ƐNd (0) values displayed by these samples (-8.5 to -10.6) does not allow effective discrimination
between the different end members.
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