Abstract: Climate Cyclicity and Accomodation Space in Semi-Arid Depositional Systems

John Howell

Although sequence stratigraphy has revolutionized the way in which marine and marginal marine depositional systems are interpreted and this approach has been extended to coastal and alluvial plain settings, similar advances have not been made within depositional systems decoupled directly from changes in sea level. In recent years attempts have been made to correlate arid and semi-arid depositional systems via recognition of changes in depositional process due to fluctuation climate. This approach provides a technique for studying such systems within a predictive chronostratigraphic framework. Theoretical modelling of the changes which occur in response to climate variation within different depositional systems indicate that the current recognition of solely drying upwards cycles is a over simplification and a variety of preserved cycles may exist. The final result is controlled by the rate of change of accomodation space, created by basin subsidence, in relation to sedimentation rates of the various depositional processes. This methodology has been applied to an extensive core and wireline log dataset from the Permian Rotliegend Group of the United Kingdom Southern North Sea. The recognition of a total of twelve variably symmetrical climate cycles has led to a greatly enhanced understanding of basin fill evolution and provided an improved regional and field-scale correlation tool. The recognition that single climate cycles have relatively uniform thickness within the basin irrespective of depositional environment, accomodation soace controls the distribution of pres rved sediment.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994