RT Journal Article T1 Parasecuencias Transgresivo-Regresivas en un Cortejo Transgresivo: parte superior de la Fm Utrillas en Olleros de Pisuerga, Palencia T1 Transgressive-regressive parasequences within a transgressive system tract: upper part of the Utrillas Fm atOlleros de Pisuerga, Palencia A1 Pujalte, Victoriano A1 Robles, Sergio AB Field and borehole data demostrate that the well-known fluviatile Utrillas Fm of N Spain is part of thetransgressive system tract of a major second-order sequence. However, the analysis of its upper part in theOlleros de Pisuerga area (Palencia) and in the Trashaedo-1 borehole reveals the existence of threeparasequences indicative of smaller scale transgressive-regressive episodes superimposed on the overalltransgressive trend. These transgressive-regressive episodes have resulted in the vertical alternation of twodifferent facies associations, a coarse-grained fluviatile association and a finer-grained littoral association,a favourable situation for the development of stratigraphic or mixed hydrocarbon traps that may prove ofinterest in future subsurface explorations YR 2008 FD 2008 LK http://hdl.handle.net/10272/8284 UL http://hdl.handle.net/10272/8284 LA spa DS Repositorio Institucional de la Universidad de Huelva RD 31 may 2026