Resumen: This study presents the cyclostratigraphic analysis of a detailed, 1,371 m-thick stratigraphic section logged in the Lower Cretaceous syn-rift lacustrine and alluvial deposits of the Enciso Group, in the eastern Cameros Basin. The spectral analysis of a time series based on lithology reveals periodic sedimentary cycles attributable to variations in the eccentricity of the Earth’s orbit around the Sun (131.8 and 39.9 m-thick sedimentary cycles for the long and short orbital eccentricity cycle) and to changes in the obliquity (12.6 m-thick cycle) and the two precession modes (7.7-5.5 m-thick cycles) of the Earth’s rotation axis. We have constructed a floating astrochronological time scale based on the spectral analysis allowing us to propose that the time interval registered in the studied series is ca. 5.4-5.7 Ma, and to estimate an average sedimentation rate of ~255-239 m/Ma. The presence of cycles representing a similar time span but having different thickness, reveals a higher influence of tectonic activity in the central and upper parts of the succession, and discriminate tectonic from climatic signal, the latter being significant throughout the succession. The sedimentary facies and paleontological content of the studied profile, deposited very close to the coastline, have allowed us to interpret a deepening-shallowing cycle that it is proposed to be eustasy- related (transgressive-regressive cycle). The anchoring of this cycle with the sea level curve in combination with the scarce paleontological dates permit the Enciso Group to be located in the Hauterivian-Barremian, that was approximately deposited between 132.5-126.8 or 132.3-126.9 Ma, depending on whether the short or long eccentricity cycle is considered, respectively. Idioma: Múltiples idiomas DOI: 10.21701/bolgeomin.131.2.003 Año: 2021 Publicado en: Boletin Geologico y Minero 131, 2 (2021), 243-268 ISSN: 0366-0176 Factor impacto CITESCORE: 0.8 - Earth and Planetary Sciences (Q4)