Statistical analysis as a tool for identification of depositional palaeoenvironments in deep-sea fans (Palaeogene formations, Central Western Carpathians, north Slovakia)

摘要

The analysis of sedimentary facies and implied model of genetic facies as well as cyclicity in vertical patterns of bed thickness with grain size distribution are frequently used to identify the depositional environment in ancient deep-water systems. Another, less conventional approach represents statistical methods to the study of the deep-sea fan environments. The object of the study is a test of practical application of the Hurst statistics, the function of cumulative distribution of bed thicknesses, the index of proximity (ABC index) and frequency histograms on four sample sections from the Central Carpathian Palaeogene Basin in the Orava region. Based on the sedimentary facies analysis, each of the successions represent different part of depositional environment of the deep-sea fan, including the channel and levee, overbank and interchannel as well as different parts of depositional lobe environments. Study shows that statistical analyses could represent an appropriate supplemental tool to the identification of depositional environment. However, the statistical analysis require a good quality and an adequate quantity of data. Their usability is also limited for successions of sufficient dataset quantity but with a mixed signal in consequence of frequent vertical variation of depositional environments, especially in more proximal parts of the deep-sea fans. The P index may reflect distality/proximity of depositional environment in the deep-sea fan and palaeo-flow regime, but fails to distinguish it from the lateral changes. Therefore, it has individually only poor information value.