Changes

==Vitrinite==

==Vitrinite==

Vitrinite is a coaly organic maceral derived from the connective tissue of vascular plants. The reflectance of vitrinite changes with heat. Vitrinite reflectance (V_r or R_o), the most commonly used thermal indicator, is the benchmark for maturation studies in the petroleum and coal industries.<ref name=ch17r36>Dow, W., G., O'Connor, D., I., 1982, Kerogen maturity and type by reflected light microscopy applied to petroleum generation, in How To Assess Maturation and Paleotem-peratures: SEPM Short Course Notes, p. 79–99.</ref> This technique is primarily useful for Devonian and younger clastic sediments and coals.

Vitrinite is a coaly organic maceral derived from the connective tissue of vascular plants. The reflectance of vitrinite changes with heat. [[Vitrinite reflectance]] (V_r or R_o), the most commonly used thermal indicator, is the benchmark for maturation studies in the petroleum and coal industries.<ref name=ch17r36>Dow, W., G., O'Connor, D., I., 1982, Kerogen maturity and type by reflected light microscopy applied to petroleum generation, in How To Assess Maturation and Paleotemperatures: SEPM Short Course Notes, p. 79–99.</ref> This technique is primarily useful for Devonian and younger clastic sediments and coals.

==Pollen and spores==

==Pollen and spores==

Pollen and spores are the organic-walled microfossils most commonly used for gauging paleotemperature. Fossil color, which changes with heating, is used to estimate a Thermal Alteration Index, or TAI.<ref name=ch17r82>Staplin, F., L., 1969, Sedimentary organic matter, organic metamorphism, and oil and gas occurrence: Bulletin of Canadian Petroleum Geology, vol. 17, no. 1, p. 47–66.</ref><ref name=ch17r56>Lerche, I., McKenna, T., C., 1991, Pollen translucency as a thermal maturation indicator: Journal of Petroleum Geology, vol. 14, no. 1, p. 19–36., 10., 1111/jpg., 1991., 14., issue-1</ref><ref name=ch17r62>Marshall, J., E., A., 1991, Quantitative spore colour: Journal of the Geological Society of London, vol. 148, p. 223–233., 10., 1144/gsjgs., 148., 2., 0223</ref> The use of pollen and spores lets us examine in situ fossils rather than evaluate an aggregate “kerogen soup.” Other organic-walled fossils [acritarchs, chitinozoans, graptolites, scolecodonts (annelid worm jaws), and dinoflagellates] have been examined for their visual and reflected values, but these fossil groups have not been rigorously calibrated to the standard vitrinite reflectance scale.<ref name=ch17r16>Bertrand, R., Heroux, Y., 1987, Chitinozoan, graptolite and scolecodont reflectance as an alternative to vitrinite and pyrobitumen reflectance in Ordovician and Silurian strata, Anticosti Island, Quebec, Canada: AAPG Bulletin, vol. 41, p. 951–957.</ref>

Pollen and spores are the organic-walled microfossils most commonly used for gauging paleotemperature. Fossil color, which changes with heating, is used to estimate a [[thermal alteration index]], or TAI.<ref name=ch17r82>Staplin, F., L., 1969, Sedimentary organic matter, organic metamorphism, and oil and gas occurrence: Bulletin of Canadian Petroleum Geology, vol. 17, no. 1, p. 47–66.</ref><ref name=ch17r56>Lerche, I., McKenna, T., C., 1991, Pollen translucency as a thermal maturation indicator: Journal of Petroleum Geology, vol. 14, no. 1, p. 19–36., 10., 1111/jpg., 1991., 14., issue-1</ref><ref name=ch17r62>Marshall, J., E., A., 1991, Quantitative spore colour: Journal of the Geological Society of London, vol. 148, p. 223–233., 10., 1144/gsjgs., 148., 2., 0223</ref> The use of pollen and spores lets us examine in situ fossils rather than evaluate an aggregate “kerogen soup.” Other organic-walled fossils—acritarchs, chitinozoans, graptolites, scolecodonts (annelid worm jaws), and dinoflagellates—have been examined for their visual and reflected values, but these fossil groups have not been rigorously calibrated to the standard vitrinite reflectance scale.<ref name=ch17r16>Bertrand, R., Heroux, Y., 1987, Chitinozoan, graptolite and scolecodont reflectance as an alternative to vitrinite and pyrobitumen reflectance in Ordovician and Silurian strata, Anticosti Island, Quebec, Canada: AAPG Bulletin, vol. 41, p. 951–957.</ref>

==Other microfossils==

==Other microfossils==

Fossils composed of phosphate (conodonts), carbonate (ostracodes), and agglutinated grains (agglutinated foraminifera) are also used for geothermometry. The organic framework of these fossils responds to thermal stress with color change. Of these, conodonts (Conodont Alteration Index, or CAI) are the most widely used<ref name=ch17r37>Epstein, A. G., Epstein, J. B., Harris, L. D., 1977, Conodont color alteration—an index to organic metamorphism: U., S. Geological Survey Professional Paper 995, p. 1–27.</ref> and conodont alteration values are calibrated to the vitrinite reflectance scale. The use of ostracodes<ref name=ch17r1>Ainsworth, N., R., Burnett, R., D., Kontrovitz, M., 1990, Ostracod colour change by thermal alteration, offshore Ireland and Western UK: Marine and Petroleum Geology, vol. 7, p. 288–297., 10., 1016/0264-8172(90)90006-3</ref> and foraminifera<ref name=ch17r64>McNeil, D., H., Issler, D., R., 1992, Correlation of foraminiferal coloration (FCI) and time-temperature (TTI) indices from Beaufort Sea exploration data: AAPG Annual Convention Abstracts, p. 87.</ref> is a newly emerging approach and is not yet calibrated to vitrinite reflectance standards. The potential of these fossils is important because they commonly occur in lithologies devoid of organic-walled fossil remains (e.g., limestones, dolomites, fine-grained sands).

Fossils composed of phosphate (conodonts), carbonate (ostracodes), and agglutinated grains (agglutinated foraminifera) are also used for geothermometry. The organic framework of these fossils responds to thermal stress with color change. Of these, conodonts ([[conodont alteration index]], or CAI) are the most widely used<ref name=ch17r37>Epstein, A. G., Epstein, J. B., Harris, L. D., 1977, Conodont color alteration—an index to organic metamorphism: U., S. Geological Survey Professional Paper 995, p. 1–27.</ref> and conodont alteration values are calibrated to the vitrinite reflectance scale. The use of ostracodes<ref name=ch17r1>Ainsworth, N., R., Burnett, R., D., Kontrovitz, M., 1990, Ostracod colour change by thermal alteration, offshore Ireland and Western UK: Marine and Petroleum Geology, vol. 7, p. 288–297., 10., 1016/0264-8172(90)90006-3</ref> and foraminifera<ref name=ch17r64>McNeil, D., H., Issler, D., R., 1992, Correlation of foraminiferal coloration (FCI) and time-temperature (TTI) indices from Beaufort Sea exploration data: AAPG Annual Convention Abstracts, p. 87.</ref> is a newly emerging approach and is not yet calibrated to vitrinite reflectance standards. The potential of these fossils is important because they commonly occur in lithologies devoid of organic-walled fossil remains (e.g., limestones, dolomites, fine-grained sands).

==Whole kerogen analysis==

==Whole kerogen analysis==