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• New approach on paleoweathering intrusive carbonatites study, Fogo Island, Cape Verde. • Weathered carbonatites in semi-arid climate are calcite rich. • The role of carbonates in the REE distribution/sequestration. • Sc, Zr, Cs, Hf, W and Br are preferably accommodated in the clay-size fraction. • Zn and Cs concentration in <50 µm and <2 µm fractions related with phyllosilicates. Intrusive carbonatites from a fluvial valley near Monte Almada (Fogo Island, Cape Verde), corresponding to the oldest unit of the island (≈4.5 Ma) occur under alkaline lavas and tuffs of more recent age in two slopes, with a very steep inclination. Its exposure with the water line fitting led to the weathering of the outcrops, and the materials are currently retained in small terraces with shrubs and trees. The motivation that drives this work was the absence of paleoweathering materials studies of these carbonatites in Fogo Island. Mineralogical and chemical analyses of paleoweathered carbonatites samples with different weathering degrees were performed by means of X-ray diffraction (XRD) and instrumental neutron activation analysis (INAA). The results obtained from fresh rock to near paleosurface samples showed that chemical contents could vary significantly in the fresh rock, particularly the trace elements, including the rare earth elements (REE), as well as in the size fractions. Besides calcite, pyroxenes and phyllosilicates, traces of anatase and K-feldspars also occur in the <2 mm fraction; dolomite was detected in one sample. Smectite, illite and kaolinite were found in the <2 µm fraction. Carbonatites weathered products are easily distinguished from other volcanic soils of Fogo Island due to higher REE contents, particularly the light and middle ones, and to higher K, Rb, Cs, W, and Th contents. Higher concentrations of Zn and Cs are observed in the silt-clay and clay-size fractions where phyllosilicates dominate, particularly smectite and illite. [ABSTRACT FROM AUTHOR]

Climate and rich volcanic soils of Fogo Island (Cape Verde) are optimal conditions for grape agriculture. This study aims a first evaluation of the bioaccumulation of essential and non-essential elements in different parts of vines of the same variety (Vitis vinifera L.), grown on recent pyroclasts and lahar deposits. Chemical composition was obtained by instrumental neutron activation analysis. A general decrease of the chemical contents occurs in the following order: barks, leaves, and grapes. Lower chemical contents were found in the grapes cultivated on the lahar deposit, except for barium. Potassium and bromine are the most accumulated. A tendency for lower transfer coefficients and enrichment factors (EF) of the chemical elements studied occur in vines grown in lahar. Significant EF of the majority of the elements studied were observed, particularly in leaves and grapes. Among the rare earth elements (REE), the heavy ones are significantly enriched in grapes. Slight positive Eu anomalies occur, which can be explained as inherited from the soil, and by a preferential uptake of Eu 2+ , replacing Ca 2+ . Among potential harmful chemical elements, significant EF (> 10) for Cr, As, Sb, W, and U in the two vines occur. Although its low concentration, the results obtained point to U bioavailability. The bioaccumulation of some chemical elements in vines from Fogo Island may be due to several factors of geogenic/natural origin, namely soil composition, airborne fine particles, and the climatic conditions of aridity with a potential availability when raindrops fall.