Abstract: Scaling in Turbidite Deposition

John Grotzinger, Daniel H. Rothman

We investigate layer-thickness distributions in four sets of turbidites ranging in age from Miocene to Early Archean. In all four sets we observe the power-law thickness distributions N(h) ^agr h-B, where N(h) is the number of layers of thickness greater than h, and B approximates 1. The first data set was obtained from formation-microscanner images obtained by Hiscott and others from offshore wells that penetrate Tertiary fore-arc turbidites, and the second is from our own measurements of turbidites in the Neoproterozoic Kingston Peak Formation, deposited in a glacially influenced rift basin. Both sets of observations exhibit roughly the same power-law distribution above a small-h cutoff, where 1.1<B<1.4 with h ranging from centimeters to meters. The third and fourth data sets ere obtained from the Permian Karoo basin and Early Archean Barberton Greenstone belt. These two data sets exhibit distinct crossovers from B<1 to B>1 at approximately 20-30 centimeters.

Motivated by the possible generality of these results, and given strong geological and sedimentological contrasts between the four data sets, we consider the available theoretical and experimental evidence that could support or deny these observations. We tentatively conclude that the power law is generic in data sets characterized by minimal erosional truncation and amalgamation, but emphasize that further study is required for full characterization. The results have implications for understanding the lateral and vertical distribution of potential reservoir beds.

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