Middle Eocene Foraminifera From the Piney Point Formation of the Virginia and Maryland Coastal Plain
This study examines the foraminiferal fauna, both benthic and planktonic, of the outcropping (45 samples) and subsurface (31 samples) middle Eocene Piney Point Formation in Virginia and Maryland. The primary objective of this study is to further refine the depositional history of the Salisbury Embay...
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ODU Digital Commons
1990
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| Online Access: | https://digitalcommons.odu.edu/oeas_etds/236 https://doi.org/10.25777/6m0w-x505 https://digitalcommons.odu.edu/context/oeas_etds/article/1236/viewcontent/Jones_MiddleEoceneForaminiferaFromThe_1990_Redacted.pdf |
| Summary: | This study examines the foraminiferal fauna, both benthic and planktonic, of the outcropping (45 samples) and subsurface (31 samples) middle Eocene Piney Point Formation in Virginia and Maryland. The primary objective of this study is to further refine the depositional history of the Salisbury Embayment which is represented by the middle Eocene Piney Point Formation. Ninety-six species of benthic and planktonic foraminifera were identified in this study. Of these, several are characteristic of the middle Eocene: Asterigerina texana, Hanzawaia danvillensis, Ceratobulimina exima, Cibicides westi, Chiloguembelitria columbiana, C. stavensis, Testacarinata inconspicua and Pseudohastigerina wilcoxensislmicra. While these were relatively abundant, diagnostic middle Eocene species such as Truncorotaloides topilensis, T. rohri and Acarinina bulbrooki were present, but quite rare. Based upon these characteristic middle Eocene foraminifera, the Piney Point Formation can be correlated with other middle Eocene Atlantic and Gulf Coastal Plain units. The benthic and planktonic foraminiferal faunas of the Piney Point Formation are most similiar to those described from the Lisbon Formation of Alabama, the Cook Mountain Formation of Louisiana and the Castle Hayne Formation of North Carolina. Examination of the benthic foraminifera using Q-mode cluster analysis on both presence/absence and abundance data reveals two distinctly different open marine biofacies of regional extent. Biofacies A, which is composed of the most shoreward localities, is characterized by species generally associated with paleodepths of between 15 and 50 meters such as Asterigerina texana, Cibicidoides tallahattaensis and Hanzawaia danvillensis, while biofacies B, composed of the most basinward localities, is characterized by species associated with paleodepths of between 50 and 150 meters, such as Epistominella danvillensis and Pyramidina subrotundata. These analyses also allowed subdivision of each of these biofacies into two smaller, more localized ... |
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