GENERIC TYPES OF STRATIGRAPHIC CYCLES CONTROLLED BY EUSTASY

Thought experiments imply that stratigraphic cycles controlled directl y by eustasy include keep-up, catch-up, catch-down (foreshortened or t runcated), and give-up variants, different patterns of thickness and f acies being governed by the interplay of sedimentation rate and accomm odation space. Most examples of these types are, in addition, base-cut out cycles, wherever lowstands of sea level dropped below the top of t he underlying cycle. Overall thicknesses of multiple cycles at any loc ale are controlled ultimately by net subsidence rate. Accordingly, eve n keep-up and catch-up cycles can faithfully record full accommodation only where tectonic subsidence during cycle formation paced eustatic fluctuation. Paradoxically, however, only condensed cycles that fortui tously compensate for syncycle tectonic subsidence can accurately reco rd the eustatic amplitude, as adjusted for water loading.