Zoe Gentes
Andrew Infante
Amy Lombari
Dennis Titterton
Jen Sullivan
 Where are major coal deposits located in the
Eastern USA?
 What were the conditions that prompted these
coals to form?
 What is the specific facies sequence in these coal
deposits?
 What can the sequence tell us about
paleoenvironment?
 Metamorphic, combustible rock formed from ancient
peat deposits
 Peat: partially decayed vascular organic matter
 Stagnant water + anaerobic conditions = environment
in which aggradation or organic matter exceeds
degradation
 Add pressure, heat, and time… Coal!
 Not necessarily tropical
 Ireland, Rhode Island
 Dense vegetation must accumulate and be covered in
mud or sediment, away from oxygen and bacteria, to
begin coal formation
 “A major extinction of peat-forming plants occurred at
the end of the Middle Pennsylvanian in the lowland
tropics of North America, due to changing climatic
conditions, probably protracted moisture deficits or
exaggeration of seasonal dryness” (DiMichele, 1996).
 The explosion of luxuriant plant growth and coal bed
formation that occurred 286 - 360 million years ago is the
"Carboniferous Period.“
 Most coals from the Pennsylvanian Period (320 to 286 million
years ago) (Cengage, 2003).
 Low and flat land, rivers flowing westward.
 Densely vegetated floodplains and coastal swamps, where
peat accumulated.
 Rivers periodically overflowed producing lacustrine
swamps, burying and compressing the peat under thick
layers of sand and mud.
 These layers formed specific sequences…
 Cyclothem
 Coal commonly occurs
in this sequence of
sedimentary strata.
 Formed from
repetition of a pattern
of sediment layers.
Typical Illinois Cyclothem 
*Different for each area of coal deposits
 In general, driven by eustatic sea level changes, or
thrust loading, or a combination.
 An idealized Pennsylvanian cyclothem: sandstone,
shale, limestone, underclay, coal, shale, limestone,
shale.
 In any one locality, cyclothems commonly repeat tens
of times with each cycle of deposition accumulated on
a previous one (Nevins, 1976).
•Relatively highgrade coals
•Kansas Coals
(Interior Province)
•Illinois Basin
(Interior Province)
•Appalachian Basin
(Eastern Province)
 Empiric Sea in the mid-continent North America.
 This sea transgressed and regressed repetitively over
millions of years.
 Marine carbonate cyclothems accumulated on a
relatively stable platform affected only moderately by
collision tectonics of North American margins.
 These cycles are eustatic, caused by the change in sea
levels (Klein, 1989).
 Peat deposited as sea
level rose.
 More than 100
cyclothems in the
Pennsylvanian and
Lower Permian rock
succession of Kansas
(Moore, 1964).
(Moore, 1964)
 Origin of depositional environment: evolution of
resurgent foreland basins in Paleozoic time.
 The Appalachian Basin was an equatorial foreland
basin bounded by the Allegheny Range, Central
Pangea Mountains to the southeast, and open
westward to the sea
 Depositional environment: a large wetland complex
drained by a fluvial system containing a mosaic of
channels, freshwater siliciclastic and carbonate lakes,
and peat swamps on a siliciclastic floodplain (Garcés,
1996).
(Garcés, 1996)
 Evolution of connected fluvial systems controlled by
subsidence in an active foreland basin, rather than to
short-term climatic change or eustacy.
 Base level changes in the fluvial system as influenced by
eustacy are considered only a very minor control of the
Appalachian cyclothem pattern.
 There are about a hundred successive cyclothems in
West Virginia (Appalachian basin) (Nevins, 1976).
 Projected time scale of deposition of one 'cycle' = about
tens of thousands of years (Garcés, 1996).
 Linked to Appalachian Basin through the same
erogeny and the building of the foreland basins.
 Also close to Kansas deposits, and thus affected by
changes in sea level and containing some marine
sediments (limestones).
 Cyclothems are intermediate between the two
end-member processes of flexural tectonics and
glacial eustasy characterizing Appalacian-type
cyclothems and Kansas-type cyclothems (Klein,
1989).
 Drop in sea level = steeper river gradient = less pooling
 Rise in sea level = shallower river gradient = more
pooling.
 50 successive cycles in Illinois (Nevins, 1976).
(Miall. 1997)
 Main condition for peat: oxygen-poor moisture in which




the rate of organic accumulation exceeds the rate of
degradation.
Coal found in East USA in the Appalachian, Illinois, and
Kansas Basins.
Coal deposits formed in Carboniferous Period
(Pennsylvanian Period 320 to 286 MYA).
Predominant sequence of strata is many-layered
cyclothems, caused by recurrent thrust loading and
eustatic changes in sea level.
Farther west towards mid-continent = more marine
deposits and more eustatically controlled strata.
Cengage, Gale, 2003, Pennsylvanian Period, World of Earth Science.,Ed. K. Lee
Lerner and Brenda Wilmoth Lerner, 2006
DiMichele, William A., Tom L. Phillips, 1996, Climate change, plant extinctions and
vegetational recovery during the Middle-Late Pennsylvanian Transition: the Case
of tropical peat-forming environments in North America, Geological Society,
London, Special Publications, v. 102; p. 201-221
Garcés, Blas L. Valero; Gierlowski-Kordesch, Elizabeth; Bragonier, William A.; 1996.
Pennsylvanian continental cyclothem development: no evidence of direct
climatic control in the Upper Freeport Formation (Allegheny Group) of
Pennsylvania (northern Appalachian Basin), Sedimentary Geology. Elsevier
Science B.V., pp. 305.
Klein, George; Willard, Debra A.; 1989. Origin of the Pennsylvanian coal-bearing
cyclothems of North America, University of Illinois at Urbana-Champaign,
Illinois 61801-2999.
Miall, Andrew D.,1997. The Geology of Stratigraphic Sequences, Springer-Verlag
Berlin Heidelberg, New York, p.162.
Moore, Raymond C., 1964, Paleoecological Aspects of Kansas Pennsylvanian and
Permian Cyclothems, Symposium on cyclic sedimentation: Kansas Geological
Survey, Bulletin 169, pp. 287-380.
Nevins, Stuart E., 1976. The Origin of Coal, Institute for Creation Research, Dallax,
TX. Weller, J. Marvin, 1930, Cyclical Sedimentation of the Pennsylvanian Period
and its Significance, The Journal of Geology, Vol. 38, No. 2, pp. 97-135 .