RT Journal Article T1 Las unidades litoestratigráficas del tránsito Triásico-Jurásico en la región de Lécera (Zaragoza) T1 The lithostratigraphic units ofthe Tríassic-Jurassic boundary at the Lécera región (Zaragoza) A1 Gómez Alday, Juan José A1 Goy, Antonio AB One of the main challenges in the stratigraphy of the Mesozoic sediments of the Iberian Ranges is the recognition ofthe Triassic-Jurassic boundary. Subsurface data provided by the hydrocarbon wells drilled in the not outcropping portions of the basin show the presence of a thick evaporitic section interbedded between the Imon and the Cuevas Labradas Fms. These evaporites are normally dissolved in the surface, where they are represented by the Carniolas of Cortes de Tajuna Fm. However, unusual cropping out of these evaporitic succession at the Lecera region has provided the opportunity to study a surface section of these evaporitic materials. The Lecera Formation, defined in this work, is composed of gypsum, anhydrite and carbonates, and can be correlated with surface and subsurface data. Palynological data confirms a Carnian age for the Keuper facies and an Hettangian age for the Carniolas located on top ofthe Lecera Fm. Regional data indicate a Rhaetian age for the carbonates of the Imon Fm. All these data confirm that the Triassic-Jurassic boundary should be located inside the here defined Lecera Fm. PB Sociedad Geológica de España YR 1997 FD 1997 LK http://hdl.handle.net/10272/10452 UL http://hdl.handle.net/10272/10452 LA spa DS Repositorio Institucional de la Universidad de Huelva RD 31 may 2026