Galatia Channel:Summary

From ILSTRAT
Jump to navigation Jump to search

Summary

1. The Houchin Creek Coal formed as an in situ peat deposit on a vast, level, stable coastal plain.
2. The Excello Shale records rapid marine transgression to the point where bottom water became anoxic because of the absence of circulation and the abundance of plant-derived organic matter.
3. The Hanover Limestone reflects restoration of normal marine circulation in deep water offshore, probably under a seasonally dry climate.
4. The Delafield Member records progradation of the shoreline into brackish water under a falling sea level, essentially filling the basin with clastic sediment.
5. The Galatia Member fills an incised valley that was cut and filled during regression to early lowstand. The river meandered actively and carried a heavy load of sand, rapidly backfilling its meander belt.
6. Springfield peat formation commenced during lowstand (maximum glaciation) under an ever-wet climate that produced a perennially high water table. Vegetation stabilized meanders of the Galatia channel, which transitioned to a black-water stream that carried only fine-grained sediment. There were no natural levees, but belts of laminated shaly coal flank the Galatia channel.
7. The Dykersburg Member records the onset of transgression, which converted the Galatia channel to an estuary and drowned the peat swamp. Vigorous tidal currents dislodged floating mats of peat, creating rolls, splits, and localized major disruption of the seam. As the climate became seasonally dry, the fluvial runoff and sediment load increased. Gray Dykersburg clastics rapidly entombed the peat.
8. Deposition of the marine Turner Mine black shale, St. David Limestone, and younger units completed the story.

The Galatia channel provides insights into events that are not recorded in most Carboniferous cyclothems. This example indicates, in conformance with some other studies (e.g., Cecil et al. 1985[1], 2003b[2], 2014[3]; Eros et al. 2012[4]; Horton et al. 2012[5]; DiMichele 2014[6]), that glacially driven sea-level fluctuations were linked to climate changes in the tropics. It also refines our understanding of when certain events (such as the development of peat) took place within the eustatic and climatic cycle. These themes are developed further in a later section of this report. For a more complete understanding of the Galatia channel, it is necessary to investigate other paleochannels related to the Springfield Coal.

Primary Source

Nelson, W.J., S.D. Elrick, W.A. DiMichele, and P.R. Ames, 2020, Evolution of a peat-contemporaneous channel: The Galatia channel, Middle Pennsylvanian, of the Illinois Basin: Illinois State Geological Survey, Circular 605, 85 p., 6 pls.

References

  1. Cecil, C.B., R.W. Stanton, S.G., Neuzil, F.T. Dulong, L.F. Ruppert, and B.S. Pierce, 1985, Paleoclimate controls on Late Paleozoic sedimentation and peat formation in the central Appalachian basin: International Journal of Coal Geology, v. 5, p. 195–230.
  2. Cecil, C.B., F.T., Dulong, R.R. West, R. Stamm, B. Wardlaw, and N.T. Edgar, 2003b, Climate controls on the stratigraphy of a Middle Pennsylvanian cyclothem in North America, in C.B. Cecil and N.T. Edgar, eds., Climate controls on stratigraphy: SEPM (Society for Sedimentary Geology) Special Publication 77, p. 151–180, https://doi.org/10.2110/pec.03.77.0151.
  3. Cecil, C.B., W.A. DiMichele, and S.D. Elrick, 2014, Middle and Late Pennsylvanian cyclothems, American Midcontinent: Ice-age environmental changes and terrestrial biotic dynamics: Comptes Rendus Geoscience, v. 346, p. 159–168.
  4. Eros, J.M., I.P. Montañez, D.A. Osleger, V.I. Davydov, T.I. Nemyrovska, V.I. Poletaev, and M.V. Zhykalyak, 2012, Sequence stratigraphy and onlap history of the Donets Basin, Ukraine: Insight into Carboniferous icehouse dynamics: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 313– 314, p. 1–25.
  5. Horton, D.E., C.J. Poulsen, I.P. Montañez, and W.A. DiMichele, 2012, Eccentricity-paced late Paleozoic climate change: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 331–332, p. 150–161.
  6. DiMichele, W.A., 2014, Wetland–dryland vegetational dynamics in the Pennsylvanian ice age tropics: International Journal of Plant Sciences, v. 175, p. 123–164.