RT Book, Section T1 Late Bajocian bioevents of ammonoid immigration and colonization in the Arequipa Basin (Pumani River area, Ayacucho, southern Peru). A1 Fernández López, Sixto Rafael A2 Chacaltana, C. A2 Tejada, L.M. A2 Morales, M.C. AB Strata of the Socosani Formation in the Pucayacu andPumani sections (Ayacucho Department, Peru), alongseveral kilometres, have yielded Upper Bajocianammonoid fossil-assemblages characterized by theoccurrence of juvenile individuals belonging to endemic orpandemic taxa, such as Megasphaeroceras andSpiroceras respectively. In addition, certain Bajocian taxarelatively common in the Mediterranean-CaucasianSubrealm, but very scarce in the Eastern PacificSubrealm, such as the strigoceratid Cadomoceras and thephylloceratid Adabofoloceras, occur in this area. TheseLate Bajocian bioevents of regional appearance ofimmigrant ammonoids and even sustained colonizationshould be associated with an episode of maximumdeepening, maximum relative sea-level rise and highestoceanic accessibility of a Bajocian-Bathoniandeepening/shallowing palaeoenvironmental cycle in theArequipa Basin, during the Late Bajocian NiortenseBiochron. PB Instituto Geológico Minero y Metalúrgico YR 2013 FD 2013 LK https://hdl.handle.net/20.500.14352/35672 UL https://hdl.handle.net/20.500.14352/35672 LA eng DS Docta Complutense RD 11 abr 2025