INAA APPLICATION IN VOLCANIC TOPSOILS OF BRAVA ISLAND (CAPE VERDE) - GEOCHEMICAL FINGERPRINTS IDENTIFICATION
Volcanic topsoils developed on Brava Island collected before the 2014–2015 eruption in the neighboring Fogo Island, show significant chemical content variations for the majority of the elements studied, even within the same geological formation. Instrumental Neutron Activation Analysis (INAA) applied to 43 topsoils allowed the determination of 30 elements and establish their geochemical variations. High contents of lithogenic trace elements like Mn, Co, Ba, La, Ce, Nd, Sm, Eu, Tb, Ta, W, Th and U are found due to the occurrence of carbonatites and phonolites. Mn, REE and W are good fingerprints for extrusive carbonatite outcrops. In general, different chemical patterns of topsoils of Brava Island reflect the highly contrasting parent materials in the semi-arid environment in Cape Verde archipelago.