cyclothem

cyclothem

[′si·klə‚them]
(geology)
A rock stratigraphic unit associated with unstable shelf of interior basin conditions, in which the sea has repeatedly covered the land.
References in periodicals archive ?
Palynological and megafloral assemblages indicate that this formation is of Asturian-Cantabrian age, with the substage boundary occurring within Cyclothem 12, about 25 m above the Hub Coal Seam (Zodrow and Cleal 1985; Zodrow 1989a, b; Dolby 1988; Cleal et al.
Measured from the base of one limestone to the base of the next, each cyclothem represents a few million years of geological time, in which depositional conditions changed from the warm clear-water marine conditions in which the limestones formed, to the more turbid deltaic and lagoonal environments in which the sandstones and shales were deposited.
Consequently, marine and nonmarine beds alternate and interfinger to form a pattern of transgressive and regressive rock deposition, which is commonly referred to as the classic Pennsylvanian cyclothem sequence.
As such, this sequence is part of a cyclothem (Gibling and Bird 1994) in a terrestrial environment of an extensive costal platform (Wightman et al.
Trace-element behavior and redox facies in core shales of Upper Pennsylvanian Kansas-type cyclothems.
1 Percentage of clastic rocks in cyclothems of Upper Carboniferous in USCB: CSS--Cracow Sandstone Series; MS--Mudstone Series; USSS--Upper Silesian Sandstone Series; PS--Paralic Series conglomerate sandstone CSS 3 81 MS 27 USSS 2 53 PS 47 Note: Table made from bar graph.
Diagenetic model for carbonate rocks in mid-continent Pennsylvanian eustatic cyclothems.
Trace element behavior and redox facies in core shales of Upper Pennsylvanian Kansas-type cyclothems.
Trace-element behaviour and redox facies in core shales of Upper Pennsylvanian Kansas-type cyclothems.
165), the Gore Lignite Measures were mainly deposited "in a range of fluvial channel, overbank splay, floodplain and swamp environments, as indicated by the presence of in situ terrestrial plant remains, lateral persistence of the multiple coal seams, common root-penetrated seat earths, large scale upward-fining clastic sequences typical of fluvial cyclothems, and the paucity of marine fauna.