Modal sequences in lithological profiles analysis - methodological approach

Abstract

The Markov chains theory is a tool commonly applied to sedimentological studies. Unfortunately, this method does not provide fully credible conclusions concerning the cyclicity of sedimentation. Such cyclicity is documented, among others, by the appearance of modal sequences, i.e., sequences many times repeated in the lithological profile and having unequivocal genetic interpretation. The paper proposes the statistical permutation test, which can verify the hypothesis of the randomness of layers succession in a given lithological profile. Applying the Monte Carlo simulation method, the probability is estimated that in a random sequence composed of the same layers as the studied profile the given number of particular sequences of layers will occur. Such attempt allows the researcher to distinguish the modal sequences, i.e., those indicating the important features of sedimentation process, from sequences whose frequent appearance results exclusively from the dominance of particular lithological varieties of rocks.