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Keywords:

  • clay minerals;
  • sedimentary sequences;
  • eustatic cycles;
  • compressive tectonics;
  • South Iberian Margin;
  • Late Oligocene;
  • Early Aquitanian

The different hydrodynamic behaviour of detrital clay minerals in the marine depositional environment allows assessment of relative sea-level variations in the sedimentary record. Comparison of smectite and kaolinite:illite (S+K:I) changes with the global sea-level curves and with the third-order cycles of the eustatic curve for European basins allows assessment of the influence of global eustasy and local tectonics on sequence stratigraphy. In the South Iberian Margin, sedimentation took place both on open-marine platforms and in deeper water areas. On this margin during the Late Oligocene to Early Aquitanian, the variations in sedimentation were caused not only by global eustasy but also by compressive tectonics. Correlations were made between the S+K:I cycles and the third-order cycles for European basins, enabling the definition of four third-order sedimentary sequences (here called C1, C2, C3, and A1) and two lower-order sequences within C3 and A1 (here called C3a, C3b, A1a, and A1b) related to tectonic movements. High S+K:I values were observed during episodes of maximum flooding in each sequence and lower-order sequence and in each succession, enabling changes in palaeocoastal morphology to be considered. Copyright © 2012 John Wiley & Sons, Ltd.