SIGNIFICANCE FOR INTERNATIONAL CORRELATION OF THE PERAPERTÚ FORMATION IN NORTHERN PALENCIA, CANTABRIAN MOUNTAINS. TECTONIC/STRATIGRAPHIC CONTEXT AND DESCRIPTION OF MISSISSIPPIAN AND UPPER BASHKIRIAN GONIATITES

Small ammonoid assemblages are recorded from the Perapertú Formation in northern Palencia. This is a mudstone unit with local platform limestones characterised by carbonate debris flows on the limestone margins. This unit, of Late Bashkirian to Early Moscovian age, participates in a series of southwards verging thrust slicesNorth of a major fault zone which originated as the head (leading edge) of a large thrust sheet with an internal deformation consisting of thrust slices and at least one nappe structure. Opposed vergencies at the head of this major thrust sheet (Carrionas Thrust Front) and the Ruesga Fault which locally modifies its trace, mark the position where the northern branch of t…