HARMONIC-ANALYSIS OF SEDIMENTARY CYCLIC SEQUENCES IN KANSAS, MIDCONTINENT, USA

Several stratigraphic sequences in the Upper Carboniferous (Pennsylvan ian) in Kansas (Midcontinent, USA) were analyzed quantitatively for pe riodic repetitions. The sequences were coded by lithologic type into s trings of datasets. The strings then were analyzed by an adaptation of a one-dimensional Fourier transform analysis and examined for evidenc e of periodicity. The method was tested using different states in codi ng to determine the robustness of the method and data. The most persis tent response is in multiples of 8-10 ft (2.5-3. 0 m) and probably is dependent on the depositional thickness of the original lithologic uni ts. Other cyclicities occurred in multiples of the basic frequency of 8-10 with persistent ones at 22 and 30 feet (6.5-9.0 m) and large ones at 80 and 160 feet (25-50 m). These levels of thickness relate well t o the basic cyclothem and megacyclothem as measured on outcrop. We pro pose that this approach is a suitable one for analyzing cyclic events in the stratigraphic record.