Difference between revisions of "Phosphatic microfossils"
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| part = Predicting the occurrence of oil and gas traps | | part = Predicting the occurrence of oil and gas traps | ||
| chapter = Applied paleontology | | chapter = Applied paleontology | ||
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| author = Robert L. Fleisher, H. Richard Lane | | author = Robert L. Fleisher, H. Richard Lane | ||
| link = http://archives.datapages.com/data/specpubs/beaumont/ch17/ch17.htm | | link = http://archives.datapages.com/data/specpubs/beaumont/ch17/ch17.htm | ||
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Phosphatic microfossils, notably conodonts, are composed of crystallites of calcium phosphate (apatite) embedded in an organic matrix. There is one type of stratigraphically significant phosphatic microfossils (conodonts); but fish teeth, of less practical utility, are found in some marine strata. | Phosphatic microfossils, notably conodonts, are composed of crystallites of calcium phosphate (apatite) embedded in an organic matrix. There is one type of stratigraphically significant phosphatic microfossils (conodonts); but fish teeth, of less practical utility, are found in some marine strata. | ||
==Conodonts== | ==Conodonts== | ||
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| − | + | [[file:applied-paleontology_fig17-8.png|thumb|300px|{{figure number|1}}Typical conodonts.]] | |
| − | The | + | Conodonts are extinct toothlike microfossils composed of calcium phosphate whose biological affinities, while poorly understood, lie with [http://www.merriam-webster.com/dictionary/chordate chordates]. Conodonts are widely distributed in marine rocks of [[Cambrian]] through [[Triassic]] age. They are excellent indicators of time and [[Thermal maturation|thermal maturity]]—especially in [[carbonate]]s, where other methods of evaluating organic thermal maturity are less successful. Conodonts are commonly used as zonal indices for the latest Cambrian through Triassic because they were abundant, evolved rapidly, and were widespread geographically.<ref name=ch17r83>Sweet, W. C., 1988, The Conodonta: morphology, taxonomy, paleoecology, and evolutionary history of a long-extinct animal phylum: Oxford University Press Monographs on Geology and Geophysics 10, 212 p.</ref> Although found in most marine rocks, conodonts are most efficiently recovered from the insoluble residues of carbonates dissolved in weak acids or from easily disaggregated [[shale]]s. |
| − | [[file:applied-paleontology_fig17-8.png| | + | Individual conodonts vary greatly in morphology, and taxonomy was originally based on the morphology of these individual specimens. While conodonts are common, the preserved remains of the soft-bodied animal that bore them are extremely rare. Based on a few preserved whole-animal specimens discovered recently (e.g., <ref name=ch17r40>Gabbott, S. E., R. J. Aldridge, and J. N. Theron, 1995, A giant conodont with preserved muscle-tissue from the Upper Ordovician of South Africa: Nature, vol. 374, p. 800–803., 10., 1038/374800a0</ref> conodonts appear to have been located in the [http://www.merriam-webster.com/dictionary/cephalic cephalic] area and may have functioned as teeth.<ref name=ch17r71>Purnell, M. A., 1995, Microwear on conodont elements and macrophagy in the first vertebrates: Nature, vol. 374, p. 798–800., 10., 1038/374798a0</ref> However, the conodont animal apparently bore many conodonts of differing shapes and morphologies, based on the study of the very rare whole-animal specimens and rare bedding-plane groupings of conodonts representing individual animals. This recent information has led to more accurate multielement species concepts. |
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| + | [[:file:applied-paleontology_fig17-8.png|Figure 1]] shows some typical conodonts. | ||
==See also== | ==See also== | ||
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* [[Microfossils in exploration]] | * [[Microfossils in exploration]] | ||
* [[Calcareous microfossils]] | * [[Calcareous microfossils]] | ||
* [[Agglutinated microfossils]] | * [[Agglutinated microfossils]] | ||
* [[Siliceous microfossils]] | * [[Siliceous microfossils]] | ||
| − | * [[ | + | * [[Palynomorphs (organic-walled microfossils)]] |
==References== | ==References== | ||
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[[Category:Predicting the occurrence of oil and gas traps]] | [[Category:Predicting the occurrence of oil and gas traps]] | ||
[[Category:Applied paleontology]] | [[Category:Applied paleontology]] | ||
| + | [[Category:Treatise Handbook 3]] | ||
Latest revision as of 18:08, 24 January 2022
| Exploring for Oil and Gas Traps | |
| |
| Series | Treatise in Petroleum Geology |
|---|---|
| Part | Predicting the occurrence of oil and gas traps |
| Chapter | Applied paleontology |
| Author | Robert L. Fleisher, H. Richard Lane |
| Link | Web page |
| Store | AAPG Store |
Phosphatic microfossils, notably conodonts, are composed of crystallites of calcium phosphate (apatite) embedded in an organic matrix. There is one type of stratigraphically significant phosphatic microfossils (conodonts); but fish teeth, of less practical utility, are found in some marine strata.
Conodonts
Conodonts are extinct toothlike microfossils composed of calcium phosphate whose biological affinities, while poorly understood, lie with chordates. Conodonts are widely distributed in marine rocks of Cambrian through Triassic age. They are excellent indicators of time and thermal maturity—especially in carbonates, where other methods of evaluating organic thermal maturity are less successful. Conodonts are commonly used as zonal indices for the latest Cambrian through Triassic because they were abundant, evolved rapidly, and were widespread geographically.[1] Although found in most marine rocks, conodonts are most efficiently recovered from the insoluble residues of carbonates dissolved in weak acids or from easily disaggregated shales.
Individual conodonts vary greatly in morphology, and taxonomy was originally based on the morphology of these individual specimens. While conodonts are common, the preserved remains of the soft-bodied animal that bore them are extremely rare. Based on a few preserved whole-animal specimens discovered recently (e.g., [2] conodonts appear to have been located in the cephalic area and may have functioned as teeth.[3] However, the conodont animal apparently bore many conodonts of differing shapes and morphologies, based on the study of the very rare whole-animal specimens and rare bedding-plane groupings of conodonts representing individual animals. This recent information has led to more accurate multielement species concepts.
Figure 1 shows some typical conodonts.
See also
- Microfossils in exploration
- Calcareous microfossils
- Agglutinated microfossils
- Siliceous microfossils
- Palynomorphs (organic-walled microfossils)
References
- ↑ Sweet, W. C., 1988, The Conodonta: morphology, taxonomy, paleoecology, and evolutionary history of a long-extinct animal phylum: Oxford University Press Monographs on Geology and Geophysics 10, 212 p.
- ↑ Gabbott, S. E., R. J. Aldridge, and J. N. Theron, 1995, A giant conodont with preserved muscle-tissue from the Upper Ordovician of South Africa: Nature, vol. 374, p. 800–803., 10., 1038/374800a0
- ↑ Purnell, M. A., 1995, Microwear on conodont elements and macrophagy in the first vertebrates: Nature, vol. 374, p. 798–800., 10., 1038/374798a0
External links
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