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Line 117: − + − • Classifying coarse-grained (>2mm) rocks. + − • Subdividing organically-bound rocks (boundstones). + − [[File:GeoWikiWriteOff2021-Abdulwahab-Figure18.png|thumbnail|Fig. 18 Extended Dunham classification (1971) [18]]] + − • Floatstone: a matrix-supported rock with > 10% of grains >2mm and original components are not organically bounded together during deposition (Figure 19). + − • Rudstone: a grain-supported rock with > 10% of grains >2mm and original components are not organically bounded together during deposition (Figure 20).+ + + + + + − • Bafflestone: in situ organically-bound rock in which organisms act as baffles (Figure 21).+ − • Bindstone: in situ organically-bound rock in which organisms encrust and bind (Figure 22).+ − • Framestone: in situ organically-bound rock in which organisms build a rigid framework (Figure 23).[k]+ + + + + + Line 137:
Line 147: − − ==Gallery== − − − [[File:GeoWikiWriteOff2021-Abdulwahab-Figure19.png|thumbnail|Fig. 19 Floatstone [19]]] − [[File:GeoWikiWriteOff2021-Abdulwahab-Figure20.png|thumbnail|Fig. 20 Rudstone [20]]] − [[File:GeoWikiWriteOff2021-Abdulwahab-Figure21.png|thumbnail|Fig. 21 Bafflestone [21]]] − [[File:GeoWikiWriteOff2021-Abdulwahab-Figure22.png|thumbnail|Fig. 22 Bindstone [22]]] − [[File:GeoWikiWriteOff2021-Abdulwahab-Figure23.png|thumbnail|Fig. 23 Framestone [23]]] − :1. {{note|a}} ^[a] Early carbonate classification is grain-size based system: Calcilutite (grains < 63 μm), calcarenite (63 μm < grains < 2mm), calcirudite (grains > 2mm). + − + − 2. ^[b] This family has restricted limits because cement by itself cannot form a rock and the supported framework component (allochems) has limited packing.+ − + − 3. ^[c] If the microcrystalline limestone had been disturbed either by bioturbation or soft-sediment deformation, the term “disturbed microcrystalline limestone” or “dismicrite” could be assigned. + − + − 4. ^[d] Examples of biolithites are: algal biolithite and coral biolithite. + − + − 5. ^[e] Naming of a subdivision is a composite of two parts. The first part refers to the name of the allochem. The second part refers to the family type. For Example, intrasparite: intra- refers to intraclasts, and –sparite refers to family I. + − + − 6. ^[f] Oosparites are more common than Oomicrites because the need of strong current to form these rocks. + − − 7. ^[g] Intrasparites are more common than intramicrites because the need of strong current to transfer course rock fragments. − − 8. ^[h] Both biosparites and biomicrites are common. However, biosparites are usually more rounded and abraded because of the strong current. − − 9. ^[i] The subdivisions could be applied considering other types of allochems: intraclasts, oolites, and pellets. − − 10. ^[j] The abundance of grains defines the nature of the framework. In other words, whether it is mud-supported or grain-supported. − − 11. ^[k] The term “boundstone” is retained if the organic bounding type is not recognized. − − ==References== − 19. ^ [1] [2] [11] Folk, R. L., 1959, Practical petrographic classification of limestones: AAPG Bulletin, v. 43, p. 1–38. − − 20. ^ [3] [4] [5] [9] Folk Classification. Wikipedia. https://en.wikipedia.org/wiki/Folk_classification#cite_ref-2 − − 21. ^ [6] Gregg, Jay. (December 18). Limestone Petrology. Missouri S&T. https://web.mst.edu/~greggjay/carbonate_page/lsgallery/pages/c-ACS190_10.htm − − 22. ^ [7] (2021, March 29). Microscopic Gallery. SEPM Strata. http://sepmstrata.org/microscopic_gallery_details.aspx?gid=165&pg=1&gcid=9 − − 23. ^ [8] (2021, March 29). Microscopic Gallery. SEPM Strata. http://www.sepmstrata.org/microscopic_gallery_details.aspx?gid=207&pg=3&gcid=11 − − 24. ^ [10] Sahraeyan, Mohammad. (2013, June). Sedimentary Basin Analysis of Sachun Formation in Southwestern Iran: Implication for Sedimentary Environments and Tectonic Setting. ResearchGate. https://www.researchgate.net/figure/Photomicrographs-showing-micrite-and-pelmicrite-in-the-argillaceous-limestone-facies-of_fig8_262337097 − − 25. ^ [12] [18] K. Bjørlykke (ed). Petroleum Geoscience: From Sedimentary Environments to Rock Physics, DOI 10.1007/978-3-642-34132-8_5, Ⓒ Springer-Verlag Berlin Heidelberg 2015. − − 26. ^ [13] Mudstone. Wikipedia. https://en.wikipedia.org/wiki/Mudstone − − 27. ^ [14] Carbonate Rock Classification. Carbonateworld. https://carbonateworld.com/carbonate-atlas/carbonate-rock-classification/images/wackstone/ − − 28. ^ [15] [16] F. Jerry Lucia. Estimating Permeability in Carbonates Using the Rock-Fabric Method. Bureau of Economic Geology. https://www.beg.utexas.edu/lmod/_IOL-CM07/cm07-step02a.htm − − 29. ^ [17] Ardakani, Omid H. (2013, June). Diagenetic evolution and associated mineralization of Middle Devonian carbonates, southwestern Ontario, Canada. ResearchGate. https://www.researchgate.net/figure/Thin-section-photomicrographs-of-Middle-Devonian-rocks-A-Syntaxial-and-equant-calcite_fig3_235413575 − − 30. ^ [19] [20] Al-Awwad, Saad F. & pomar, Luis. (2015, May 21). Origin of the rudstone–floatstone beds in the Upper Jurassic Arab-D reservoir, Khurais Complex, Saudi Arabia. ScienceDirect. https://www.sciencedirect.com/science/article/pii/S0264817215001634 − − 31. ^ [21] Khanaqa, Polla. (2018, December). Stratigraphy and Facies Analysis of the Govanda Formation from Western Zagros, Kurdistan Region, Northeastern Iraq. ResearchGate. https://www.researchgate.net/figure/a-Photo-of-the-Coral- − Bafflestone-of-Barda-Balaka-Outcrop-Between-the-stems-Fine_fig12_330094098 − − 32. ^ [22] Bindstone. Bureau of Economic Geology. https://www.beg.utexas.edu/lmod/_IOL-CM02/st21-ancbindstone.htm − − 33. ^ [23] Camuera, Jon. (2014, July). Origin and palaeo-environmental significance of the Berrazales carbonate spring deposit, North of Gran Canaria Island, Spain. ResearchGate. https://www.researchgate.net/figure/A-Framestone-facies-composed-of-parallel-plant-moulds-coated-with-calcite-B-Plant_fig4_283498781 − − ==Sources== − 1. Lokier, Stephen W.; Al Junaibi, Mariam (2016). "The petrographic description of carbonate facies: are we all speaking the same language?". Sedimentology. 63 (7): 1843–1885. doi:10.1111/sed.12293 − − 2. Folk, R. L., 1959, Practical petrographic classification of limestones: AAPG Bulletin, v. 43, p. 1–38. − − 3. Folk, R.L., 1962, Spectral subdivision of limestone types, in Ham, W.E., ed., Classification of carbonate Rocks-A Symposium: American Association of Petroleum Geologists Memoir 1, p. 62-84. − − 4. Dunham, R. J., 1962, Classification of carbonate rocks according to depositional texture, in Ham, W. E., ed., Classification of Carbonate Rocks: AAPG Memoir 1, p. 108–121. − 5. Embry, Ashton F.; Klovan, J. Edward (1971-12-01). "A late Devonian reef tract on northeastern Banks Island, N.W.T". Bulletin of Canadian Petroleum Geology. 19 (4): 730–781.+ + − 6. K. Bjørlykke (ed). Petroleum Geoscience: From Sedimentary Environments to Rock Physics, DOI 10.1007/978-3-642-34132-8_5, Ⓒ Springer-Verlag Berlin Heidelberg 2015.+ + + + + + + + + + + +
Carbonate sedimentary rocks classification (view source)
Revision as of 14:09, 19 December 2023
, 14:09, 19 December 2023→Extended Dunham Classification (1971)
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In oil and gas industry, classifying carbonate rocks is a major step in core and thin section description. Two classification systems have been widely used in the industry:
In oil and gas industry, classifying carbonate rocks is a major step in core and thin section description. Two classification systems have been widely used in the industry:
# Folk (1959,1962) Classification
# Folk (1959<ref name=Flk1959>Folk, R. L., 1959, [https://archives.datapages.com/data/bulletns/1957-60/data/pg/0043/0001/0000/0001.htm Practical petrographic classification of limestones]: AAPG Bulletin, v. 43, p. 1–38.</ref>, 1962<ref name=Flk1962>Folk, R. L., 1962, [https://archives.datapages.com/data/specpubs/carbona2/data/a038/a038/0001/0050/0062.htm Spectral subdivision of limestone types], ''in'' W. E. Ham, ed., Classification of carbonate Rocks-A Symposium: [https://archives.datapages.com/data/alt-browse/aapg-special-volumes/m1.htm AAPG Memoir 1], p. 62-84.</ref>) Classification
# Dunham (1962) Classification
# Dunham (1962<ref name=Dnhm>Dunham, R. J., 1962, [https://archives.datapages.com/data/specpubs/carbona2/data/a038/a038/0001/0100/0108.htm Classification of carbonate rocks according to depositional texture], ''in'' W. E. Ham, ed., Classification of Carbonate Rocks: [https://archives.datapages.com/data/alt-browse/aapg-special-volumes/m1.htm AAPG Memoir 1], p. 108–121.</ref>) Classification
Both classifications provide an indication of depositional energy setting and reservoir quality.
Both classifications provide an indication of depositional energy setting and reservoir quality.
* Wentworth (1922){{note|a}} [a]
* Wentworth (1922){{note|a}} [a]
* Bramkamp & Powers (1958)
* Bramkamp & Powers (1958)
* Folk (1959,1962)
* Folk (1959, 1962)<ref name=Flk1959 /><ref name=Flk1962 />
* Dunham (1962)
* Dunham (1962)<ref name=Dnhm />
* Leignton & Pendexter (1962)
* Leignton & Pendexter (1962)
* Todd (1966)
* Todd (1966)
* Embry & Klovan (1971)
* Embry & Klovan (1971)<ref name=EmbryKlvn>Embry, A. F., and J. E. Klovan, 1971, A late Devonian reef tract on northeastern Banks Island, N.W.T: Bulletin of Canadian Petroleum Geology, v. 19, no. 4, p. 730–781.</ref>
* Wright (1992)
* Wright (1992)
* Hallsworth & Knox (1999)
* Hallsworth & Knox (1999)
Among all of the attempts, Folk (1959, 1962) and Dunham (1962) extended by Embry & Klovan (1971) classifications were widely accepted.
Among all of the attempts, the Folk<ref name=Flk1959 /><ref name=Flk1962 /> and Dunham<ref name=Dnhm />, extended by Embry & Klovan<ref name=EmbryKlvn />, classifications were widely accepted.
==Folk Classification==
==Folk Classification==
===Folk’s Criteria===
===Folk’s Criteria===
Folk classification system is based on three basic components of limestone:
[[w:Folk classification|Folk's classification]] system is based on three basic components of limestone:
* Allochems (sediment grains): framework component of the rock. There are four major types of allochems in Folk system: intraclasts, oolites, fossils, and pellets.
* Allochems (sediment grains): framework component of the rock. There are four major types of allochems in Folk system: intraclasts, oolites, fossils, and pellets.
* Microcrystalline lime mud: matrix component of the rock < 4 μm in size.
* Microcrystalline lime mud: matrix component of the rock < 4 μm in size.
* Pelmicrite: consists of pellets with microcrystalline matrix (Figure 10).
* Pelmicrite: consists of pellets with microcrystalline matrix (Figure 10).
<gallery mode=packed heights=300px widths=300px>
<gallery mode=packed heights=300px widths=300px>
File:GeoWikiWriteOff2021-Abdulwahab-Figure7.png|{{figure number|7}}Intramicrite
File:GeoWikiWriteOff2021-Abdulwahab-Figure7.png|{{figure number|7}}Intramicrite<ref>[http://sepmstrata.org/microscopic_gallery_details.aspx?gid=165&pg=1&gcid=9 SEPM Strata Microscopic Gallery]</ref>
File:GeoWikiWriteOff2021-Abdulwahab-Figure8.png|{{figure number|8}}Oomicrite
File:GeoWikiWriteOff2021-Abdulwahab-Figure8.png|{{figure number|8}}Oomicrite<ref>[http://www.sepmstrata.org/microscopic_gallery_details.aspx?gid=207&pg=3&gcid=11 SEPM Strata Microscopic Gallery]</ref>
File:GeoWikiWriteOff2021-Abdulwahab-Figure9.png|{{figure number|9}}Biomicrite
File:GeoWikiWriteOff2021-Abdulwahab-Figure9.png|{{figure number|9}}Biomicrite
File:GeoWikiWriteOff2021-Abdulwahab-Figure10.png|{{figure number|10}}Pelmicrite
File:GeoWikiWriteOff2021-Abdulwahab-Figure10.png|{{figure number|10}}Pelmicrite
==Dunham Classification==
==Dunham Classification==
===Dunham’s Criteria===
===Dunham’s Criteria===
Dunham classification system is based on three depositional textural features:
[[w:Dunham classification|Dunham's classification system]] is based on three depositional textural features:
* The presence or absence of lime mud.
* The presence or absence of lime mud.
* The abundance of grains.[j]
* The abundance of grains.[j]
===Extended Dunham Classification (1971)===
===Extended Dunham Classification (1971)===
Embry and Klovan expanded the original Dunham classification due to the lack of:
Embry and Klovan<ref name=EmbryKlvn /> expanded the original Dunham classification due to the lack of:
* Classifying coarse-grained (>2mm) rocks.
* Subdividing organically-bound rocks (boundstones).
The extended Dunham Classification is shown in Figure 18.
The extended Dunham Classification is shown in Figure 18.
[[File:GeoWikiWriteOff2021-Abdulwahab-Figure18.png|center|framed|200px|{{Figure number|18}}Extended Dunham classification (1971)]]
====Coarse-Grained Rocks Classification====
====Coarse-Grained Rocks Classification====
* Floatstone: a matrix-supported rock with > 10% of grains >2mm and original components are not organically bounded together during deposition (Figure 19).
* Rudstone: a grain-supported rock with > 10% of grains >2mm and original components are not organically bounded together during deposition (Figure 20).
<gallery mode=packed heights=250px widths=250px>
File:GeoWikiWriteOff2021-Abdulwahab-Figure19.png|{{figure number|19}}Floatstone
File:GeoWikiWriteOff2021-Abdulwahab-Figure20.png|{{figure number|20}}Rudstone
</gallery>
====Organically-Bound Rocks Subdivision====
====Organically-Bound Rocks Subdivision====
* Bafflestone: in situ organically-bound rock in which organisms act as baffles (Figure 21).
* Bindstone: in situ organically-bound rock in which organisms encrust and bind (Figure 22).
* Framestone: in situ organically-bound rock in which organisms build a rigid framework (Figure 23).[k]
<gallery mode=packed heights=250px widths=250px>
File:GeoWikiWriteOff2021-Abdulwahab-Figure21.png|{{figure number|21}}Bafflestone
File:GeoWikiWriteOff2021-Abdulwahab-Figure22.png|{{figure number|22}}Bindstone
File:GeoWikiWriteOff2021-Abdulwahab-Figure23.png|{{figure number|23}}Framestone
</gallery>
===Depositional Energy Setting and Reservoir Quality Indications===
===Depositional Energy Setting and Reservoir Quality Indications===
Rudstones and framestones are usually formed in high-energy settings (above wave base).
Rudstones and framestones are usually formed in high-energy settings (above wave base).
Organically-bound rocks show good reservoir quality if the skeletal growth is interconnected.
Organically-bound rocks show good reservoir quality if the skeletal growth is interconnected.
==Notes==
==Notes==
# [a] Early carbonate classification is grain-size based system: Calcilutite (grains < 63 μm), calcarenite (63 μm < grains < 2mm), calcirudite (grains > 2mm).
# [b] This family has restricted limits because cement by itself cannot form a rock and the supported framework component (allochems) has limited packing.
# [c] If the microcrystalline limestone had been disturbed either by bioturbation or soft-sediment deformation, the term “disturbed microcrystalline limestone” or “dismicrite” could be assigned.
# [d] Examples of biolithites are: algal biolithite and coral biolithite.
# [e] Naming of a subdivision is a composite of two parts. The first part refers to the name of the allochem. The second part refers to the family type. For Example, intrasparite: intra- refers to intraclasts, and –sparite refers to family I.
# [f] Oosparites are more common than Oomicrites because the need of strong current to form these rocks.
# [g] Intrasparites are more common than intramicrites because the need of strong current to transfer course rock fragments.
# [h] Both biosparites and biomicrites are common. However, biosparites are usually more rounded and abraded because of the strong current.
# [i] The subdivisions could be applied considering other types of allochems: intraclasts, oolites, and pellets.
# [j] The abundance of grains defines the nature of the framework. In other words, whether it is mud-supported or grain-supported.
# [k] The term “boundstone” is retained if the organic bounding type is not recognized.
==References==
{{reflist}}
==Other Sources==
* Gregg, Jay. (December 18). Limestone Petrology. Missouri S&T. https://web.mst.edu/~greggjay/carbonate_page/lsgallery/pages/c-ACS190_10.htm
* Sahraeyan, Mohammad. (2013, June). Sedimentary Basin Analysis of Sachun Formation in Southwestern Iran: Implication for Sedimentary Environments and Tectonic Setting. ResearchGate. https://www.researchgate.net/figure/Photomicrographs-showing-micrite-and-pelmicrite-in-the-argillaceous-limestone-facies-of_fig8_262337097
* K. Bjørlykke (ed). Petroleum Geoscience: From Sedimentary Environments to Rock Physics, DOI 10.1007/978-3-642-34132-8_5, Ⓒ Springer-Verlag Berlin Heidelberg 2015.
* Carbonate Rock Classification. Carbonateworld. https://carbonateworld.com/carbonate-atlas/carbonate-rock-classification/images/wackstone/
* F. Jerry Lucia. Estimating Permeability in Carbonates Using the Rock-Fabric Method. Bureau of Economic Geology. https://www.beg.utexas.edu/lmod/_IOL-CM07/cm07-step02a.htm
* Ardakani, Omid H. (2013, June). Diagenetic evolution and associated mineralization of Middle Devonian carbonates, southwestern Ontario, Canada. ResearchGate. https://www.researchgate.net/figure/Thin-section-photomicrographs-of-Middle-Devonian-rocks-A-Syntaxial-and-equant-calcite_fig3_235413575
* Al-Awwad, Saad F. & pomar, Luis. (2015, May 21). Origin of the rudstone–floatstone beds in the Upper Jurassic Arab-D reservoir, Khurais Complex, Saudi Arabia. ScienceDirect. https://www.sciencedirect.com/science/article/pii/S0264817215001634
* Khanaqa, Polla. (2018, December). Stratigraphy and Facies Analysis of the Govanda Formation from Western Zagros, Kurdistan Region, Northeastern Iraq. ResearchGate. https://www.researchgate.net/figure/a-Photo-of-the-Coral-Bafflestone-of-Barda-Balaka-Outcrop-Between-the-stems-Fine_fig12_330094098
* Bindstone. Bureau of Economic Geology. https://www.beg.utexas.edu/lmod/_IOL-CM02/st21-ancbindstone.htm
* Camuera, Jon. (2014, July). Origin and palaeo-environmental significance of the Berrazales carbonate spring deposit, North of Gran Canaria Island, Spain. ResearchGate. https://www.researchgate.net/figure/A-Framestone-facies-composed-of-parallel-plant-moulds-coated-with-calcite-B-Plant_fig4_283498781
* Lokier, Stephen W.; Al Junaibi, Mariam (2016). "The petrographic description of carbonate facies: are we all speaking the same language?". Sedimentology. 63 (7): 1843–1885. doi:10.1111/sed.12293