Malvern: Late/Upper Maastrichtian, Arkansas
List of taxa
Where & when
Geology
Taphonomy & methods
Metadata & references
Taxonomic list
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Coccolithophyceae
- Microrhabdulaceae
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Lithraphidites quadratus
Bramlette and Martini 1964
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Cephalopoda
- Ammonitida
- Scaphitidae
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Discoscaphites iris
Conrad 1858
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Discoscaphites minardi
Landman et al. 2004
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Cephalopoda
- Ammonitida
- Baculitidae
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Baculites sp.
Lamarck 1799
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Geography
| Country: | United States | State/province: | Arkansas | County: | Hot Springs |
| Coordinates: | 34.4° North, 91.9° West (view map) | ||||
| Paleocoordinates: | 38.6° North, 69.3° West | ||||
| Basis of coordinate: | stated in text | ||||
| Geographic resolution: | small collection |
Time
| Period: | Cretaceous | Epoch: | Late/Upper Cretaceous |
| Stage: | Maastrichtian | 10 m.y. bin: | Cretaceous 8 |
| Key time interval: | Late/Upper Maastrichtian | Ammonoid zone: | Discoscaphites iris |
| Age range of interval: | 72.10000 - 66.00000 m.y. ago |
Stratigraphy
| Formation: | Arkadelphia |
| Stratigraphic resolution: | formation |
Lithology and environment
| Primary lithology: | nodular,gray marl |
| Lithology description: "The Malvern site exposes a mixed siliciclastic-carbonate sequence of the uppermost Maastrichtian Arkadelphia Formation unconformably overlain by the Paleocene Clayton Formation of the Midway Group. The Arkadelphia Formation consists of a ~9 m thick poorly fossiliferous, thoroughly bioturbated, massive dark gray marl with scattered granular size phosphatic nodules. Thin beds of light gray packstone occur at 4 m, 4.2 m, 7.1 m, 7.4 m, and 7.8 m below the formational contact. The packstone beds have sharp contacts with the marl and generally are poorly fossiliferous to non-fossiliferous with the exception of the uppermost bed. The uppermost packstone bed contains a mixture of fragmented and whole molluscan shells, shark teeth, and phosphatic nodules, which is consistent with the bed described by Becker et al. (2010). The top of the Arkadelphia Formation is marked by a sharp, undulating contact. The base of the overlying Clayton Formation consists of a 20 cm, normally graded, poorly sorted, laminated, glauconitic, quartz-rich sand with abundant impact spherules, fragmented shells, granular-size phosphatic nodules, and rip-up clasts of Arkadelphia lithology." (Larina et al. 2016) | |
| Environment: | marginal marine indet. |
Taphonomy
| Modes of preservation: | body |
| Size of fossils: | macrofossils,mesofossils,microfossils |
Collection methods and comments
| Collection methods: | field collection |
| Reason for describing collection: | biostratigraphic analysis |
| Museum repositories: | AMNH |
| Taxonomic list comments:Taxon abundances by bed can be found in the original reference | |
Metadata
| Also known as: | AMNH Loc. 3596 | ||
| Database number: | 205795 | ||
| Authorizer: | A. Dunhill | Enterer: | B. Allen |
| Created: | 2019-10-22 09:30:04 | Last modified: | 2019-10-22 09:30:04 |
| Access level: | the public | Released: | 2019-10-22 09:30:04 |
| Creative Commons license: | CC BY | ||
Reference information
Primary reference:
| 70564. | E. Larina, M. Garb, N. Landman, N. Dastas, N. Thibault, L. Edwards, G. Phillips, R. Rovelli, C. Myers and J. Naujokaityte. 2016. Upper Maastrichtian ammonite biostratigraphy of the Gulf Coastal Plain (Mississippi Embayment, southern USA). Cretaceous Research 60:128-151 [A. Dunhill/B. Allen] |