MECHANISMS FOR THE FORMATION OF CRATONIC STRATIGRAPHIC SEQUENCES

North American Phanerozoic cratonic strata comprise six transgressive/ regressive sequences separated by interregional unconformities. The me chanism of formation of the sequences and their bounding unconformitie s remain uncertain. Although eustasy probably contributed, it cannot h ave acted alone in their formation, as testified by syn-depositional f aulting and post-depositional tilting of strata. We have developed a t hree-dimensional stratigraphic model which incorporates vertical motio ns from dynamic topography, background cratonic subsidence, eustasy, d enudation, mixed carbonate and elastic deposition, Airy isostasy in re sponse to loading and unloading, and mechanical compaction. The model has been used to test possible contributions of eustasy, epeirogeny an d background subsidence to patterns of cratonic strata. The results de monstrate the potential of dynamic topography to account for observed long-wavelength tilting. They also demonstrate the importance of backg round subsidence on the craton in providing accommodation space to acc umulate and preserve the observed thicknesses of stratigraphic sequenc es.