Evolution of palynofloras across the Triassic/Jurassic boundary in the central sector of the Iberian Range, Spain

Abstract The palynology of the Triassic–Jurassic boundary has been studied in the central sector of the Iberian Range (central Spain). Twenty-two productive samples from five sections contained well-preserved palynological assemblages including 72 taxa. Sediments were collected in different lithostratigraphic units, spanning the Late Carnian to the Early Jurassic. Most levels with Keuper facies were Carnian in age and their assemblages were integrated by diverse operculate, monosaccate and bisaccate gymnosperm pollen. It is inferred that the source vegetation that colonized central Iberia was similar to the one characterizing western Tethys during the late Middle to early Late Triassic. By contrast, all the studied levels from the upper Norian, uppermost Keuper, to the Lower Jurassic facies were dominated by Classopollis (80–100%). It is inferred that the structure of vegetation changed from a diversified conifers/seed ferns forests to a more homogeneous, lower diversity, cheirolepid-dominated, woodland during the late Norian. By the Rhaetian, the vegetation had acquired a structure which remained relatively stable for more than 15 million years until the Pliensbachian. It is then suggested that the events that characterized biotic changes of the Triassic/Jurassic boundary did not affect the vegetation of Central Iberia in any significant way.