Alternating sequences of marine and non-marine sediments
In
geology, cyclothems are alternating
stratigraphic sequences of marine and non-marine
sediments, sometimes interbedded with
coal seams. The cyclothems consist of repeated sequences, each typically several meters thick, of
sandstone resting upon an
erosion surface, passing upwards to
pelites (finer-grained than sandstone) and topped by coal.
Historically, the term was defined by the European coal geologists[2] who worked in coal basins formed during the
Carboniferous and earliest
Permian periods. Depositional sequences have been thoroughly studied by oil geologists using geophysical profiles of continental and marine basins. A general theory of basin-scale deposition has been formalized under the name of
sequence stratigraphy.[3]
^Wanless, H.R.; Weller, J.M. (1932). "Correlation and extent of Pennsylvanian cyclothems". Geological Society of America Bulletin. 43 (4): 1003–1016.
Bibcode:
1932GSAB...43.1003W.
doi:
10.1130/gsab-43-1003.
^Hampson G, Stollhofen H, Flint S (1999) A sequence stratigraphic model for the Lower Coal Measures (Upper Carboniferous) of the Ruhr district, north-west Germany. Sedimentology vol. 46 (issue 6), pp. 1199-1231
^Haq BU, Schutter SR (2008) A chronology of Paleozoic sea-level changes. Science, vol. 322 (issue 5898), pp. 64-68.
doi:
10.1126/science.116164
^Stanley, Steven M. Earth System History. New York: W.H. Freeman and Company, 1999.
ISBN0-7167-2882-6 (p. 426)