FORMATION OF SEQUENCES IN THE CRATONIC INTERIOR OF NORTH-AMERICA BY INTERACTION BETWEEN MANTLE, EUSTATIC, AND STRATIGRAPHIC PROCESSES

Models integrating geodynamic and stratigraphic processes show that so me gross features of Phanerozoic North American cratonic strata can be explained with dynamic topographies generated by subduction and cycle s of supercontinent aggregation and dispersal, A three dimensional fin ite-element model is used to calculate mantle flow beneath North Ameri ca during Phanerozoic time in response to episodes of subduction at cr atonic margins and two cycles of supercontinent formation and breakup, Dynamic topographies calculated by the flow models are used as input to a stratigraphic model that also includes background subsidence, eus tasy, denudation, elastic and carbonate deposition, compaction, and is ostasy. These models successfully reproduce aspects of the Sloss seque nces; the best matches were obtained by combining two wavelengths of d ynamic topography with second-order eustasy, Long-wavelength dynamic t opography generates first-order stratal cyclicity, Periods of erosion were shorter when North America was over a dynamic topography low than when it was over a high, Long-wavelength dynamic topography also expl ains the absence of Mesozoic strata on the eastern portion of the crat on, Characteristic stratal patterns are shown to result from subductio n-related dynamic topography, although sensitive to sediment supply an d other subsidence mechanisms, Aspects of Upper Cretaceous stratal pat terns may be explained by the effects of Farallon plate subduction, Ge nerally, strata deposited in a dynamic topography depression have low preservation potential because the topography is reversible. Thus, anc ient subduction-related dynamic topography is most likely to be repres ented by unconformities.