U–Pb geochronology of REE–Nb–Ta–U–Th minerals in the NW Amazonian Craton: Evidence for two Mesoproterozoic mineralization events

Abstract

Critical-metal mineralization in the NW Amazonian Craton remains poorly constrained in age, limiting our understanding of the timing and tectonomagmatic context of Mesoproterozoic metallogenic processes. To address this gap, we present direct LA–ICP–MS U–Pb geochronology of REE–Nb–Ta–U–Th–bearing accessory minerals from eastern Colombia and southern Venezuela. Heavy-mineral concentrates from the Espina Hills (Guainía, Colombia) and the El Burro–Aguamena area (Venezuela) contain ilmenorutile, monazite, and xenotime associated with quartz–muscovite pegmatitic colluvium. U–Pb data yield crystallization ages of 1394 ± 19 Ma (xenotime), 1395 ± 12 Ma (monazite), and 1345 ± 12 to 1348 ± 15 Ma (ilmenorutile and monazite), defining two discrete Mesoproterozoic mineralization pulses recorded by texturally and compositionally coherent mineral populations. These ages correspond to late-stage alkaline to pegmatitic magmatism coeval with the Parguaza and Matraca rapakivi granites, indicating prolonged anorogenic crustal melting and HFSE–REE enrichment between ∼1.40 and 1.34 Ga.

Beyond their geochronological significance, the combined mineralogical, chemical, and isotopic signatures provide a robust provenance framework linking detrital heavy-mineral assemblages to concealed felsic–pegmatitic sources in northern Amazonia, thereby contributing to regional metallogenic models and mineral traceability efforts.