Growth dynamics and ecology of Upper Jurassic mounds, with comparisons to Mid-Palaeozoic mounds

The Mid-Palaeozoic, including the Late Jurassic, was a time of both widespread coral reef growth and pronounced mound formation. A comparison of mound features and their general setting highlights, despite all differences, general similarities in overall growth dynamics. Mound formation was frequently driven by discontinuous patterns, particularly by background sedimentation. In many examples, episodes of mound stabilisation by early lithification, growth of microbolite crusts and winnowing of fines was followed by growth episodes of benthic fauna under reduced to negligible background sedimentation. This pattern of variable sedimentation and organic buildups may have occurred in different orders and magnitudes, inducing a fractal pattern in some mound complexes. A composite approach in estimating growth rates of mounds demonstrates that high-frequency oscillations necessary for growth of most mounds might have ranged from a few thousand years to 4th and 5th order Milankovich cycles that were superimposed by autocyclic factors.