RT Journal Article T1 The Jurassic – Cretaceous transition in the West Cameros Basin (Tera Group, Burgos, Spain): Sedimentological and palynostratigraphical insights A1 Rodríguez Barreiro, Iván A1 Santos, Artai A. A1 Arribas Mocoroa, María Eugenia A1 Mas Mayoral, José Ramón A1 Arribas Mocoroa, José A1 Villanueva Amadoz, Uxue A1 Torcida Fernández-Baldor, Fidel A1 Diez, José B. AB The Jurassic–Cretaceous boundary transition is widely distributed within the West Cameros Basin. This horizon is constituted by the Tera Group, consisting of two depositional sequences (DS1 and DS2) comprising four geological formations spanning the Tithonian to the Berriasian. Here, a combined sedimentological and palynostratigraphic study was made covering the Tera Group. The sedimentological results for the DS 1 differentiate three facies associations (FA 1-1, 1-2 and 1-3) corresponding to floodplains and braided channels of a distributive fluvial system shifting to shallow lacustrine facies in a semi-arid climate. For the DS 2, three FA were also differentiated (FA 2-1, 2-2, and 2-3), corresponding to tidal-influenced meandering channels and floodplains in a distal fluvial to a delta-plain system that shifts to shallow lacustrine facies. The palynological results were only productive in samples from the Jaramillo Formation. The palynological record shows an assemblage dominated by spores including Concavissimisporites, Leptolepidites and Taurocusporites, as well as Classopollis pollen. According to the stratigraphic ranges of some selected taxa, the suggested chronostratigraphic assignment is lower Berriasian for the Jaramillo Fm. A comparison of the microfloras from the Tithonian–Berriasian recorded in the Iberian Peninsula was carried out. The following observations can be concluded: 1) the change in the plant communities, already observed since the Late Jurassic onwards, became more pronounced between the Tithonian–Berriasian boundary and the late Berriasian; and 2) a noteworthy occurrence of some biostratigraphically important taxa, specifically for the Tithonian–Berriasian interval. PB Elsevier SN 0195-6671 YR 2022 FD 2022-07-04 LK https://hdl.handle.net/20.500.14352/72093 UL https://hdl.handle.net/20.500.14352/72093 LA eng NO Ministerio de Economía y Competitividad (MINECO) NO Xunta de Galicia NO Chinese Academy of Sciences NO Universidad Complutense de Madrid NO European Union NO UNiversidad de Vigo DS Docta Complutense RD 23 jul 2024