Application of Markov chain analysis to a fining-upward fluvial succession of the Early Permian Warchha Sandstone, Salt Range, Pakistan

Abstract

Markov chain analysis is applied to the cyclic properties and degree of ordering of lithofacies in the Early Permian (Artinskian) Warchha Sandstone. The 30 to 155 m-thick Warchha Sandstone is well exposed in the Salt Range, Pakistan and dominantly composed of sandstone, siltstone and claystone succession. Seven lithofacies have been identified on the basis of geometry, gross lithology and sedimentary structures. Lithofacies are cyclically arranged in a fining-upward pattern. A complete cycle starts with pebbly sandstone accomplished by thin layer of basal conglomerate and terminates with claystone. The non-stationary first order Markov chains have been applied statistically on vertical transition of facies using outcrop data of the Warchha Sandstone succession. Later, a chi-square test was applied to test the dependency between any two facies states in facies transitions. The results of this study reveal that the sediments of the Warchha succession were controlled by Makovian mechanism and as a whole represent fluvial succession deposited in a predictable cyclic arrangement of lithofacies.