The petrographic analysis in calcite minerals in carbonatitic dykes from Fuerteventura Basal Complex (Ajuy, Punta de la Nao) shows the presence of isolated primary fluid inclusions, corrobora-ting their magmatic origin instead of a late-stage origin. Micro-ther-mometric studies in calcite show a restricted range of apparent eutectic temperature (Te*= -21.7 – -21.0 °C) and final ice melting temperatures (Tim= -3.2 – -2.1. °C). Homogenization temperatures and pressures are in the range of 140-210 °C and 4-16 bars respecti-vely. Our results suggest the binary NaCl-H2O system as a characte-rizing chemical system in studied fluid inclusions, with the presence of low salinity fluids (≈ 5 wt. % NaCleq), probably related with fluid/rock interactions