Can The Ginsburg Model Generate Cycles?

Abstract

The Ginsburg model of carbonate accumulation is an often-quoted mechanism for generating so-called autocycles. It is shown that the model does not represent a self-oscillating system; oscillations can only be generated if at least two critical parameters controlling sedimentation are introduced. The Ginsburg model is a conceptual model which tries to explain the behavior of some carbonate shelves that undergo continuous tectonic subsidence and that carry on their surface a very active carbonate factory. Unfortunately the original model has only been published in abstract form—the relevant part of which is quoted here in full (Ginsburg, 1971, p. 340): . . . "The Florida Bay lagoon and the tidal flats of the Bahamas and Persian Gulf are traps for line sediment produced on the large adjacent open platforms or shelves. The extensive source areas produce carbonate mud by precipitation and by the disintegration of organic skeletons. The carbonate mud moves shoreward by wind-driven, tidal or estuarinelike circulation, and deposition is accelerated and stabilized by marine plants and animals. Because the open marine source areas are many times larger than the nearshore traps, seaward progradation of the wedge of sediments is inevitable. This seaward progradation gives a regressive cycle from open marine shelf or platform to supratidal flat. As the shoreline progrades seaward the size of the open marine source area decreases; eventually reduced production of mud no longer exceeds slow continuous subsidence and a new transgression begins. When the source area expands so that production again exceeds subsidence a new regressive cycle starts.". . . The author is very grateful to Dr. Ginsburg for supplying some additional information that is not obvious from the abstract. The subsidence must be differential and a broad, open shelf that gradually tilts seaward is visualized. All of the sediment produced on the shelf is transported shoreward, where it accumulates as a wedge-shaped deposit that builds into a tidal bank. A further analysis of the model is interesting for two reasons. First, the model has been and still is seriously suggested as a possible mechanism to explain cyclicity on carbonate platforms (see Goldhammer et al, 1987, for references).