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The AAPG/Datapages Combined Publications Database
Abstract: Gulf Coastal Plain Marker Fossils in the Revised Miliolidae
The foraminiferal family Miliolidae no longer includes the genera with a porcellaneous wall as seen in reflected light. The genera comprising the miliolids, as recently defined, have a three-fold, pitted wall and the potential of becoming the best marker genera, stratigraphically and/or environmentally, in the Gulf Coastal Plain Tertiary. The genera with the preceding characteristics are: Miliola, Neaguites, Texina, Picouina, Helentappanella, Hemimiliola, Heteromiliola, and Miliolacostata.
Of the samples studied, the Moodys Branch Formation (Eocene) and the Byram Formation (Oligocene) in Mississippi bear the largest number of individual specimens -- six of the eight genera of the miliolids in the Gulf Coastal Plain. The Crystal River Formation (Eocene) and the Chipola Formation (Miocene) in Florida have a lesser number of miliolids with most having a quinqueloculine chamber arrangement that is similar to the many genera in the Lutetian of France.
The Weches Formation (Eocene) in Texas and the Cane River Formation (Eocene) in Louisiana, also in the samples studied, have two different miliolid genera, Texina and Heteromiliola respectively. The pelagic foraminifera present in the Cane River indicates that its sediment was deposited in deeper water than the Weches. The Yazoo Formation (Eocene) and the Rosefield Formation (Oligocene) in Louisiana, and the Red Bluff and Byrum Formations (Oligocene) in Mississippi also bear the miliolid genus Heteromiliola thus adding credence to it being an environmental marker genus for the Miliolidae.
Marker genera for the basal Eocene appears to be Hemimiliola and Helentappanella; and for the Oligocene the genera Neaguites, Miliolacostata and Picouina.
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ACKNOWLEDGMENTS AND ASSOCIATED FOOTNOTES
LSU Geology & Geophysics Department, Professor emeritus, Baton Rouge, LA
Copyright © 1999 by The Gulf Coast Association of Geological Societies