SCALING IN TURBIDITE DEPOSITION

We propose that the distribution of layer thicknesses of turbidite dep osits that show minimal erosional truncation and amalgamation should o bey the power law N(h) is-proportional-to h(-B), where N(h) is the num ber of layers of thickness greater than h and B congruent-to 1. We sup port this proposal with two sets of observations, one from formation-m icroscanner images obtained in offshore wells that penetrate Tertiary fore-arc turbidites (Hiscott et al. 1992) and the other from our own f ield measurements of turbidites in the Neoproterozoic Kingston Peak Fo rmation, deposited in a glacially influenced rift basin. Both sets of observations show roughly the same power-law distribution above a smal l-h cutoff. Motivated by the possible generality of these results, and given strong geological and sedimentological contrasts between the tw o data sets, we consider the available theoretical and experimental ev idence that could support or deny these observations. We tentatively c onclude that the power law is generic in data sets characterized by mi nimal erosional truncation and amalgamation but emphasize that further study is required for a definitive statement. Proceeding from the ass umption that the scaling law is valid for arbitrarily thin layers, we derive an upper bound for B. We then detail simple and plausible assum ptions that provide a theoretical estimate of B. We discuss possible r amifications of this analysis for the interpretation of further data.