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The Iquitos Arch corresponds to a broad topographic high in the Western Amazonia. Morphostructural and geophysical data and flexural modeling show that the Iquitos Arch is the present-day forebulge of the Northwestern Amazonian foreland basin. A detailed tectono-sedimentary study of the Neogene and Quaternary deposits of the Iquitos area has been carried out in order to circumscribe the timing of the forebulge uplift and its environmental consequences. The Neogene and Quaternary sedimentary succession of the Iquitos Arch consists of six formations that evolved from tidal to fluvial environments. The first three formations exhibit Late Miocene gliding features and synsedimentary normal faults. Such soft-sediment deformations bear witness to tectonic activity ascribed to the growth of the forebulge. Regional erosive surfaces that separate the Neogene and Quaternary formations recorded the progressive …