Datos bioestratigráficos de los materiales silúricos del Sinclinal de Herrera del Duque (Badajoz)

The 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