Pieren Pidal, Agustín PedroGutiérrez Marco, Juan Carlos2023-06-202023-06-2019900213-683Xhttps://hdl.handle.net/20.500.14352/60391The Silurian sequen ce in the Herrera del Duque syncline (Southern Central /berian zone) starts with 20 m. of black shales (Guadarranquejo Formation) which lay disconformably upon the Hirnantian diamictites (Gualija Formation). Within the black shales, eight graptolite horizons have been recorded (A-H) and two (/-1) at the base of the overlying sandy alternances. A Telychian (post-Turriculatus Zone) age for the Guadarranquejo Formation has been suggested, the L1andovery/Wenlock boundary Iying probably near its top.spajournal articlehttp://www.sociedadgeologica.es/publicaciones_geogaceta.htmlopen access56:551.7SilurianBiostratigraphyGraptolitesCentral Iberian zoneHesperian MassifGeología estratigráfica2506.19 Estratigrafía