Siltstone

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Siltstone
Sedimentary rock
Siltstone

Siltstone, also known as aleurolite,

clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility.[2]

Although its permeability and porosity is relatively low, siltstone is sometimes a

hydraulic fracturing for economic gas production.[5]

Siltstone was prized in ancient Egypt for manufacturing statuary and cosmetic palettes. The siltstone quarried at Wadi Hammamat was a hard, fine-grained siltstone that resisted flaking and was almost ideal for such uses.[6]

Description

Holtzclaw siltstone, Louisville, Kentucky

There is not complete agreement on the definition of siltstone. One definition is that siltstone is mudrock (

field by chewing a small sample; claystone feels smooth while siltstone feels gritty.[2]

Siltstones differ significantly from sandstones due to their smaller pores and a higher propensity for containing a significant clay fraction. Although often mistaken for a shale, siltstone lacks the laminations and fissility along horizontal lines which are typical of shale.[2] Siltstones may contain concretions.[9][10] Unless the siltstone is fairly shaly, stratification is likely to be obscure and it tends to weather at oblique angles unrelated to bedding.

Origin

Siltstone is an unusual rock, in which most of the silt grains are made of quartz.[11] The origin of quartz silt has been a topic of much research and debate.[12][13] Some quartz silt likely has its origin in fine-grained foliated metamorphic rock,[14] while much marine silt is likely biogenic,[15][16] but most quartz sediments come from granitic rocks in which quartz grains are much larger than quartz silt.[17] Highly energetic processes are required to break these grains down to silt size.[18] Among proposed mechanism are glacial grinding;[19][20] weathering in cold, tectonically active mountain ranges;[18] normal weathering, particularly in tropical regions;[11][21][22] and formation in hot desert environments by salt weathering.[23]

Siltstones form in relatively quiet depositional environments where fine particles can settle out of the transporting medium (air or water) and accumulate on the surface.[24] They are found in turbidite sequences,[25] in deltas,[26] in glacial deposits,[27] and in miogeosynclinal settings.[28]

Locations with siltstone donation

Footnotes

  1. ^ Gyöngyi Farkas Characterization of subterranean bacteria in the Hungarian Upper Permian Siltstone (Aleurolite) Formation Canadian Journal of Microbiology 46(6):559-64
  2. ^ a b c Blatt, Middleton & Murray 1980, pp. 381–382.
  3. doi:10.1306/05181110171
    .
  4. doi:10.1016/j.marpetgeo.2017.02.020
    .
  5. ^ Ben E. Law and Charles W. Spencer, 1993, "Gas in tight reservoirs-an emerging major source of energy", in David G. Howell (ed.), The Future of Energy Gasses, US Geological Survey, Professional Paper 1570, p.233-252.
  6. ISBN 0192854194
    . Retrieved 2 October 2020.
  7. ISBN 0-914696-14-9. Archived from the original
    on 2006-02-14. Retrieved 2 October 2020.
  8. doi:10.1306/74D7221B-2B21-11D7-8648000102C1865D
    .
  9. S2CID 129030770
    .
  10. doi:10.1016/0037-0738(95)00092-5
    .
  11. ^
    doi:10.1111/j.1365-3091.1982.tb01706.x
    .
  12. doi:10.1016/S1040-6182(00)00044-6
    .
  13. doi:10.1016/1040-6182(90)90035-3
    .
  14. ^ Blatt, Middleton & Murray 1980, p. 284.
  15. ISBN 9781405177832
    .
  16. S2CID 4417951
    .
  17. ISBN 0387904301
    .
  18. ^
    doi:10.1016/S0012-8252(98)00035-X
    .
  19. doi:10.1306/74D71ED3-2B21-11D7-8648000102C1865D
    .
  20. doi:10.1016/0037-0738(74)90022-0
    .
  21. doi:10.1016/S1040-6182(99)00018-X
    .
  22. doi:10.1016/0037-0738(83)90050-7
    .
  23. doi:10.1016/S0140-1963(18)31786-5
    .
  24. ISBN 0393924076
    .
  25. ^ Jaworowski, K. (2013). Facies analysis of the Silurian shale-siltstone succession in Pomerania (northern Poland). Geological Quarterly, 44(3), 297-315. Retrieved from https://gq.pgi.gov.pl/article/view/8078
  26. ^ Lineback, Jerry Alvin. "Deep-water sediments adjacent to the Borden Siltstone (Mississippian) delta in southern Illinois." Circular no. 401 (1966).
  27. S2CID 46570542
    .
  28. doi:10.1306/212F70EF-2B24-11D7-8648000102C1865D
    .

References

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