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Finite Markov chain model in lithofacies analysis: an example from the bida sandstone, Bida Basin, Nigeria


A.U Okoro
H.N Ezeh

Abstract

The Markov Chain Stochastic Process has been used both to analyze the vertical lithofacies of the Bida Sandstone (Campanian – Maastrichtian) in Bida area and interprete the corresponding depositional systems. Six lithofacies, comprising of F1: conglomerates (breccias); F2 : medium – very coarse, pebbly sandstone with dominant trough beddings ; F3: coarse-grained pebbly sandstone with small scale trough or planar cross-beds; F4: mediumgrained planar cross- bedded or massive sandstone lithofacies with abundant scattered pebbles ; F5: very fine to fine -grained, planar cross-bedded or parallel laminated sandstones; and F6: siltstone and claystone, variegated and mottled in places - ripple/parallel laminations and rootlets were recognised. A high frequency fining-upward (FU) transition pattern (or cycles) with a “memory function” was distilled from the sequence using the Markov Chain Stochastic Process. The fining- upward (FU) motif is interpreted as a product of braided river depositional system with well- developed flood plains and lakes behind non-cohesive river banks. The cycles indicate channel migration within a broad topographically variable alluvial plain, fed by basin-margin fans.

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eISSN: 2992-4502
print ISSN: 1596-6798