Jump to content

Coal ball

This is a good article. Click here for more information.
From Wikipedia, the free encyclopedia

This is an old revision of this page, as edited by EdwardLane (talk | contribs) at 10:06, 22 February 2012 (→Contents: added some links). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

Coal ball
A greyish-brown round object with some pits and horizontal lines. The coal ball is located on a white paper. The background contains a white sheet of paper, tape, and a mug on an office desk.
A coal ball
Composition
PrimaryCalcite
SecondaryPermineralised life forms

Coal balls, despite their name, are calcium-rich masses of permineralised life forms, generally having a round shape. Coal balls were formed roughly 300 million years ago (mya), during the Carboniferous Period. They are exceptional at preserving organic matter, which makes them useful to scientists, who cut and peel the coal balls to research the geological past of the Earth.

In 1855, two English scientists, Joseph Dalton Hooker and Edward William Binney, made the first scientific description of coal balls in England, and the initial research on coal balls was carried out in Europe. It was not until 1922 that coal balls were identified and described in North America. Since then, coal balls have been found in other countries, and they have led to the discovery of over 300 species and 130 genera.

Coal balls may be found in coal seams across North America and Eurasia. North American coal balls are relatively widespread, both stratigraphically and geologically, as compared to coal balls from Europe. The oldest known coal balls were found in Germany and the former Czechoslovakia.

Introduction to the scientific world, and formation

Portrait of Sir Joseph Dalton Hooker
Sir Joseph Dalton Hooker, who along with Edward William Binney was the first to report on coal balls

The first scientific description of coal balls was made in 1855 by Sir Joseph Dalton Hooker and Edward William Binney, who reported on examples found in the coal seams of Yorkshire and Lancashire, England. European scientists did much of the early research on these objects.[1][2] Coal balls in North America were found in coal seams since the 1890s,[3] although the connection to European coal balls was not made until Adolph Carl Noé (whose coal ball was actually found by Gilbert Cady[3]) drew the parallel in 1922.[4][2]

Hooker and Binney believed that coal balls were formed in situ – organic matter gently accumulated near a peat bog and was permineralised, a process of fossilisation in which mineral deposits form internal casts of organisms.[5][6] Water with a high dissolved mineral content was buried along with the plant matter in a peat bog. As the dissolved ions crystallised, the mineral matter precipitated out. This caused concretions containing plant material to form and preserve as rounded lumps of stone. This process prevented coalification and preserved the peat, eventually turning it into a coal ball.[7] The majority of coal balls are found in bituminous and anthracite coal seams,[8][9] in locations where the peat was not sufficiently compressed to render the material into coal.[7][10]

In addition to Hooker and Binney, Marie Stopes and David Watson also analysed their own coal ball samples. Like Hooker and Binney, they decided that coal balls formed in situ, but added that interaction with a marine environment was necessary for a coal ball to form.[11]

Contents

Plate-like entities relatively larger than surrounding structures that resemble small bubbles.
Calcite and microdolomites are common materials found in coal balls

Notwithstanding the word "coal" in their name, coal balls are not made of coal (they are nonflammable and useless for fuel),[12][13] but rather calcium-rich permineralised life forms,[10] mostly containing calcium and magnesium carbonate, iron pyrite, silica, and carbonate of lime.[14][15] Coal balls are usually about the size of a man's fist,[16] though their sizes have been known to vary greatly, having been described as ranging from that of a walnut up to three feet in diameter.[17]

Coal balls commonly contain microdolomites, products of aragonite,[10] and masses of organic matter at various stages of decomposition.[7][18][19] Hooker and Binney analysed a sample of a coal ball, finding "a lack of coniferous wood ... and fronds of ferns", and that the discovered plant matter "appeared to [have been arranged] just as they fell from the plants that produced them".[5]

In 1962, Sergius Mamay and Ellis Yochelson discovered signs of marine animal remains in North American coal balls.[20][21]

In 2000, it was noted that the carbonate found in the most concentrated coal balls from coal seams in Herrin, Illinois have 13C/12C ratios as low as –34‰, consistent with CO2 production by anaerobic oxidation of methane.[22] This microbial phenomenon has only been credited since the mid 1990s because, although many factors indicated the process was likely, the energy margin of methane oxidation coupled with sulfate reduction was known to be minuscule. For instance, it was noted[23] that salt dome cap carbonates have isotopes consistent with methane metabolism, though a flood of contemporaneous literature assessing the salt domes as potential waste repositories insisted that the process required more complex hydrocarbon seeps on the basis of thermodynamics. In the mid-1990s, researchers began describing active anaerobic oxidation of methane precipitating carbonates in various anoxic sea and lake floors, such as the Black Sea. The radial fibrous calcite of coal balls is echoed by the radial structure in 1-2 m tall towers built over methane seeps.[24]

Preservation

The quality of preservation in coal balls varies from no preservation to the point of being able to analyse the cellular structures.[6] Some coal balls have been found to contain preserved root hairs[13] and are described as being "more or less perfectly well-preserved",[25] containing "not what used to be the plant – it is the plant";[26] while others have been described as "[containing] almost no preserved plant remains".[10] Coal balls with well-preserved contents have been used as a means of analysing the geographical distribution of the vegetation they contain, providing evidence that Ukrainian and Oklahoman plants of the tropical belt were once the same.[27]

Three main factors determine the quality of preserved material in a coal ball: the mineral constituents, speed of the burial process, and degree of compression before undergoing permineralisation.[13] Generally, coal balls resulting from remains that have a quick burial with little decay and pressure are more well preserved, although plant remains in most coal balls almost always show differing signs of decay and collapse.[7] Coal balls containing quantities of iron sulphide have far lower preservation than coal balls permineralised by magnesium or calcium carbonate,[7] which has earned iron sulphide the title "chief curse of the coal ball hunter".[13]

Distribution

Coal balls were first found in England,[5] and later in other parts of Eurasia, including Belgium, Holland, former Czechoslovakia, Germany, the former Soviet Union, and more recently, China.[1][10] They were also encountered in North America, where, compared to Europe, they are relatively widespread.[1] In the United States, coal balls have been found from the Illinois Basin[28] to Ohio and the Appalachian region,[7] with ages varying from the later Stephanian (roughly 304 to 299 mya) to the later end of the Westphalian (roughly 313 to 304 mya). European coal balls generally originate from the early end of the Westphalian Stage.[1] The age of coal balls generally ranges from the Permian Period (299 to 251 mya) to the Upper Carboniferous,[29] though the oldest coal balls were of early Namurian age (326 to 313 mya) and were discovered in Germany and former Czechoslovakia.[1]

Analysis

A number of thin web-like sheets greatly overlapping each other in one place, in others less. The section of the coal ball resembles broken glass. A thick, dark line can be seen.
A thin section of a coal ball

Thin sectioning was the first procedure used to analyse fossilised material contained in coal balls. The procedure was created and used by Hooker and Binney,[5][3][25][30] and involved cutting a coal ball with a diamond saw, flattening, polishing, and gluing the thin section to a slide, then placing it under a petrographic microscope for examination.[10][31] This process could be done with a machine, although the large amount of time needed and the poor quality of samples produced by thin sectioning gave way to a more convenient method.[1][32]

The thin section technique was superseded by the now-common liquid peel technique in 1928.[1][30] In the liquid peel technique, peels are obtained by cutting the surface of a coal ball with a diamond saw, grinding the cut surface on a glass plate with silicon carbide to a smooth finish, and etching the cut and the surface with hydrochloric acid.[32] The acid dissolves the mineral matter from the coal ball, and leaves a projecting layer of plant cells.[13] Acetone should be applied and a piece of cellulose acetate.[15] This embeds the cells preserved in the coal ball into the cellulose acetate. Upon drying, the cellulose acetate can be removed from the coal ball with a razor and the obtained peel can be stained with a low-acidity stain and observed under a microscope.[18][13][33][34] Up to 50 peels can be extracted from 2 millimetres of coal ball with this method.[32]

X-ray powder diffraction has also been used to analyse coal balls.[10] In X-ray diffraction, X-rays of a predetermined wavelength are sent through a sample to examine its structure. It reveals information about the crystallographic structure, chemical composition, and physical properties of the examined material. The scattered intensity of the X-ray pattern is observed and analysed, with the measurements consisting of incident and scattered angle, polarisation, and wavelength or energy.[35]

See also

References

  1. ^ a b c d e f g Scott, Andrew C. (1985). "The formation and significance of Carboniferous coal balls" (PDF). Philosophical Transactions of the Royal Society. B 311 (1148): 123–137. JSTOR 2396976. Retrieved 15 July 2011. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  2. ^ a b Noé, Adolph C. (30 March 1923). "Coal Balls". Science. 57 (1474). American Association for the Advancement of Science: 385. doi:10.1126/science.57.1474.385. JSTOR 1648633. PMID 17748916.
  3. ^ a b c Darrah, William Culp; Lyons, Paul C (1995). Historical Perspective of Early Twentieth Century Carboniferous Paleobotany in North America. United States of America: Geological Society of America. ISBN 0813711851.
  4. ^ Noé, Adolph C. (June 1923). "A Paleozoic Angiosperm". The Journal of Geology. 31 (4): 344–347. Bibcode:1923JG.....31..344N. doi:10.1086/623025. JSTOR 30078443.
  5. ^ a b c d Hooker, Joseph Dalton (1855). "On the structure of certain limestone nodules enclosed in seams of bituminous coal, with a description of some trigonocarpons contained in them". Philosophical Transactions of the Royal Society of London. 145. Britain: Royal Society: 149–156. doi:10.1098/rstl.1855.0006. JSTOR 108514. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  6. ^ a b Perkins, Thomas (1976). "Textures and Conditions of Formation of Middle Pennsylvanian Coal Balls, Central United States" (PDF). University of Kansas. Retrieved 16 July 2011.
  7. ^ a b c d e f Phillips, Tom. "Fossil Peats from the Illinois Basin: A guide to the study of coal balls of Pennsylvanian age" (PDF). University of Illinois. Retrieved 16 July 2011. {{cite web}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  8. ^ "coal ball (paleontology) – Britannica Online Encyclopedia". Britannica.com Inc. Archived from the original on 28 July 2011. Retrieved 8 July 2011. {{cite web}}: Unknown parameter |deadurl= ignored (|url-status= suggested) (help)
  9. ^ "Paleobotany". Cleveland Museum of Natural History. Archived from the original on 10 September 2011. Retrieved 10 September 2011. {{cite web}}: Unknown parameter |deadurl= ignored (|url-status= suggested) (help)
  10. ^ a b c d e f g Barwood, Henry L (1995). "Mineralogy and origin of coal balls". Geological Society of America North Central and South Central Section: 37.
  11. ^ Stopes, Marie C.; Watson, David M. S. (1908). "On the Present Distribution and Origin of the Calcareous Concretions in Coal Seams, Known as 'Coal Balls'". Philosophical Transactions of the Royal Society of London. 200. Britain: Royal Society: 167–218. Bibcode:1909RSPTB.200..167S. JSTOR 91931.
  12. ^ "a photo gallery of meteorwrongs". Archived from the original on 28 July 2011. Retrieved 9 July 2011. {{cite web}}: Unknown parameter |deadurl= ignored (|url-status= suggested) (help)
  13. ^ a b c d e f Andrews, Henry N. (April 1946). "Coal Balls - A Key to the Past". The Scientific Monthly. 62 (4): 327–334. JSTOR 18958.
  14. ^ Lomax, James (1903). "On the occurrence of the nodular concretions (coal balls) in the lower coal measures". Report of the annual meeting. 72. British Association for the Advancement of Science: 811–812.
  15. ^ a b Gabel, Mark L. (February 1986). "Making Coal Ball Peels to Study Fossil Plants". The American Biology Teacher. 48 (2). University of California Press: 99–101. JSTOR 4448216. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  16. ^ "Ore Deposits Under Study – Chicago University professor to engage in research work". Evening Independent. 19 June 1923. p. 13. Retrieved 1 September 2011.
  17. ^ Feliciano, José Maria (1 May 1924). "The Relation of Concretions to Coal Seams". The Journal of Geology. 32 (3). The University of Chicago Press: 230–239. Bibcode:1924JG.....32..230F. doi:10.1086/623086. JSTOR 30059936.
  18. ^ a b "PBIO 460/560 Paleobotany; Cutting a Coal Ball". Archived from the original on 28 July 2011. Retrieved 9 July 2011. {{cite web}}: Unknown parameter |deadurl= ignored (|url-status= suggested) (help)
  19. ^ "Fossils – Window To The Past (Permineralisation)". Archived from the original on 28 July 2011. Retrieved 8 July 2011. {{cite web}}: Unknown parameter |deadurl= ignored (|url-status= suggested) (help)
  20. ^ Holmes, J (1981). "A note on the occurrence of marine animal remains in a Lancashire coal ball (Westphalian A)". Geological Magazine. 118 (3): 307–308. doi:10.1017/S0016756800035809. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  21. ^ Mamay, Sergius H. (1962). "Occurrence and significance of marine animal remains in American coal balls". Geological Survey: 193–224. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help) Occurrence and significance of marine animal remains in American coal balls at Google Books
  22. ^ Demaris, Philip J (2000). "Formation and distribution of coal balls in the Herrin Coal (Pennsylvanian), Illinois Basin". Journal of the Geological Society. 157: 221–228. doi:10.1144/jgs.157.1.221.
  23. ^ Posey (1988). "Fluid-rock interactions in the salt dome environment". Chemical Geology. 74: 203. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  24. ^ Michaelis (August 2002). "Microbial reefs in the Black Sea fueled by anaerobic oxidation of methane". Science. 297. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  25. ^ a b Seward, Albert Charles (1898). Fossil plants: a text-book for students of botany and geology. Cambridge University Press. pp. 84–87.
  26. ^ Phillips, Tom L. "T L 'Tommy' Phillips, Department of Plant Biology, University of Illinois". University of Illinois. Archived from the original on 31 July 2011. Retrieved 31 July 2011. {{cite web}}: Unknown parameter |deadurl= ignored (|url-status= suggested) (help)
  27. ^ Phillips, Tom L. (February 1984). "Changing patterns of Pennsylvanian coal-swamp vegetation and implications of climatic control on coal occurrence". International Journal of Coal Geology. 3 (3): 205–255. doi:10.1016/0166-5162(84)90019-3. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  28. ^ DiMichele, William A (1988). "Paleoecology of the Middle Pennsylvanian-Age Herrin Coal Swamp (Illinois) Near a Contemporaneous River System, the Walshville Paleochannel" (PDF). Review of Paleobotany and Palyntology. 56. Elsevier Science Publishers BV Amsterdam: 151–176. doi:10.1016/0034-6667(88)90080-2. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  29. ^ Jones, T. P.; Rowe, N. P. (1999). Fossil plants and spores: modern techniques. London: Geological Society. ISBN 9781862390355. {{cite book}}: Invalid |ref=harv (help)
  30. ^ a b Phillips, Tom L. (1973). "Development of Paleobotany in the Illinois Basin" (PDF). Illinois State Geological Survey. Retrieved 15 September 2011. {{cite web}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  31. ^ University of Chicago Department. of Geology (1915). The Journal of Geology. University of Chicago Press.
  32. ^ a b c Seward, A. C. (2010). Plant Life Through the Ages: A Geological and Botanical Retrospect. Cambridge University Press. ISBN 1108016006. {{cite book}}: |access-date= requires |url= (help)
  33. ^ "Coal Ball Peel Technique". University of Ohio. Archived from the original on 2 August 2011. Retrieved 2 August 2011.
  34. ^ "NMNH Paleobiology: Illustration Techniques". paleobiology.si.edu. Smithsonian Institution. 2007. Archived from the original on 10 August 2011. Retrieved 9 August 2011. {{cite web}}: Unknown parameter |deadurl= ignored (|url-status= suggested) (help)
  35. ^ "Materials Research Lab – Introduction to X-ray Diffraction". Materials Research Lab. University of Santa Barbara, California. 2011. Archived from the original on 25 August 2011. Retrieved 25 August 2011. {{cite web}}: Unknown parameter |deadurl= ignored (|url-status= suggested) (help)
Retrieved from "https://en.wikipedia.org/w/index.php?title=Coal_ball&oldid=478226564"