CYCLICITY AND LITHOFACIES MODELLING BY APPLICATION OF MARKOV CHAIN ANALYSIS TO THE WARCHHA SANDSTONE, SALT RANGE, PAKISTAN

The Early Permian Warchha Sandstone is well exposed in the Salt Range and dominantly composed of sandstone, siltstone and claystone sequence. Seven lithofacies have been identified in the Warchha Sandstone 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 in outcrop data of the Warchha Sandstone succession from the Matan and the Sanwans areas of the Salt Range. A stimulation strategy was developed by transition intensity matrix to determine the facies-by-facies transitions. Later, a chi-square test was applied to test the dependency between any two facies states, during facies transitions. This study strongly support that the sediments of the Warchha Succession was deposited by Makovian mechanism and as a whole represents fluvial sedimentation deposited in a predictable cyclic arrangements of lithofacies.