Statistical Basis for Cyclothems: A Quantitative Study of the Sedimentary Succession in the East Pennine Coalfield

Abstract

SUMMARY Study of cyclic sedimentation in the Coal Measures is impeded by confused terminology and ideas. It is suggested that the first steps in the investigation of an area or sequence where cyclic sedimentation is suspected should be: (1) to determine statistically if a modal cycle is present and to define that cycle, (2) to erect a composite sequence representative of the succession. The Coal Measures of the East Pennine (Yorkshire‐Derbyshire‐Nottinghamshire) Coalfield. England, are examined to illustrate the application of this idea. The succession shows a modal cycle of non‐marine shale followed upwards by seat‐earth with secondary modes (also non‐marine sediments) made up of shale—siltstone—shale—seat‐earth and shale—siltstone and sandstone—shale—seat‐earth. The composite sequence for the whole succession is marine shale—non‐marine shale—siltstone and sandstone—non‐marine shale—seat‐earth. Consideration of cycle types, horizontal and vertical variation and thickness, lead to the suggestion that sedimentational controls played the major part in the development of the cyclic succession in the Coal Measures of the East Pennine Coalfield. Only three horizons are exceptional and suggest the possibility of regional diastrophic controls or world‐wide changes of sea level.

Logan Medallist 3. Making Stratigraphy Respectable: From Stamp Collecting to Astronomical Calibration

“…There is no discussion of repetitiveness or cyclicity in this paper, but the work was clearly foundational for the very important papers by Nanz's Shell colleagues that followed less than a decade later (see below). Duff and Walton (1962) demonstrated that the cyclothem concept had become very popular by the early 1960s. For example, J.R.L.…”

“…Allen, who is credited as one of the two originators of the meandering river point-bar model for fluvial deposits, used the term cyclothem for cycles in the Old Red Sandstone in his first papers on these deposits (Allen 1962(Allen , 1964. Duff and Walton (1962) addressed the widespread use (and misuse) of the term cyclothem, and discussed such related concepts as modal cycle, ideal cycle, idealized cycle, and theoretical cycle, the differences between cyclicity, rhythmicity and repetition, and the possible value of statistical methods for refining cyclic concepts. They speculated about the possibility of repeated delta-lobe migration as a cause of cyclicity, in contrast to the prevailing interpretation of the cycles as the product of sea-level change.…”

“…Interestingly (and this highlights one of the arguments of this paper that some ideas develop as separate lines of research, which take time to come together), Visher's paper makes no reference to what are now the classic papers on Bouma's turbidite model (Bouma 1962), or Allen's (1964Allen's ( , 1965) work on alluvial deposits, which include his block diagram of a fluvial point-bar. However, Beerbower's (1964) description of autocyclicity and Duff and Walton's (1962) speculation about deltaic processes (neither of which are referenced by Visher) indicate the beginnings of what shortly became a flood of new work providing the basis for the facies model revolution. Early applications of these ideas to the interpretation of the subsurface are exemplified by Berg's (1968) study of an interpreted point-bar complex constituting a reservoir unit in Wyoming.…”

Analysis of lithofacies cyclicity in the Miocene Coal Complex of the Bełchatów lignite deposit, south-central Poland

“…The atypical αvalue (0.1 instead of 0.05) resulted from the intention of revealing even the weak statistical effects of cyclicity. Privileged transitions, typically pointed out by means of a set of right-sided z-tests, are traditionally used to construct facies relationship diagrams -FRD (see Duff & Walton, 1962;Gradziński et al, 1986). These transitions are the basis for revealing cycles in sedimentary processes.…”

Lateral Clay Mineral Variations in Certain Pennsylvanian Underclays

“…Logan (1842), Worthen (1866, p.59), Potonie (1910), Baker (1962), and Duff and Walton (1962) considered underclays to be fossil soils. Stout (1923), McMillan (1956), and Senstius (1958) felt that underclays formed in a manner similar to gleys.…”