Documentation of the Santonian­ Campanian and Austinian-Tayloran Stage Boundaries in Mississippi and Alabama Using Calcareous Microfossils U.S. GEOLOGICAL SURVEY BULLETIN 1884 AVAILABILITY OF BOOKS AND MAPS OF THE U.S. GEOLOGICAL SURVEY Instructions on ordering publications of the U.S. Geological Survey, along with prices of the last offerings, are given in the cur­ rent-year issues of the monthly catalog "New Publications of the U.S. Geological Survey." Prices of available U.S. Geological Sur­ vey publications released prior to the current year are listed in the most recent annual "Price and Availability List" Publications that are listed in various U.S. Geological Survey catalogs (see back inside cover) but not listed in the most recent annual "Price and Availability List" are no longer available. 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Peck, Director Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government UNITED STATES GOVERNMENT PRINTING OFFICE: 1989 For sale by the Books and Open-File Reports Section U.S. Geological Survey Federal Center, Box 25425 Denver, CO 80225 Library of Congress Cataloging in Publication Data Dowsett, Harry J. Documentation of the Santonian-Campanian and Austinian-Tayloran stage boundaries in Mississippi and Alabama using calcareous microfossils I Harry J. Dowsett. p. em. -(U.S. Geological Survey bulletin : 1884) Bibliography: p. Supt. of Docs. no. I 19.3 : 1884 1. Stratigraphic correlation-Mississippi. 2. Stratigraphic correlation­ Alabama. 3. Paleontology, Stratigraphic-Cretaceous. 4. Paleontology, Stratigraphic-Mississippi. 5. Paleontology, Stratigraphic-Alabama. 6. Foraminifera, Fossil-Mississippi. 7. Foraminifera, Fossil-Alabama. 8. Ostracoda, Fossil-Mississippi. 9. Ostracoda, Fossil-Alabama. 10. Plankton, Fossil-Mississippi. 11. Plankton, Fossil-Alabama. I. Title. II. Series. QE75.B9 no. 1884 [QE652.55.U6] 557.3 s-dc20 89-600080 [551.7'09762] Cl p Documentation of the Santonian-Campanian and Austinian-Tayloran Stage Boundaries in Mississippi and Alabama Using Calcareous Microfossils By Harry J. Dowsett Abstract ing correlations with the type Austin and Taylor units in Identification of foraminifers, calcareous nannofos­ Texas and were using the terms "Austin" and "Taylor" in a sils, and ostracodes in samples from the Upper Creta­ chronostratigraphic sense (Stephenson and Monroe, 1940; ceous Eutaw, Mooreville, and Demopolis Formations of Stephenson and others, 1942; Cushman, 1946; Monroe, Mississippi and Alabama allows correlations between the 1946; Parks, 1958; Shaver, 1958). Based on previously standard European and provincial Gulf Coast Stages. The published data, the chronostratigraphic position of the Austinian-Tayloran boundary, represented by a sediment­ Austinian-Tayloran Stage boundary should fall within the ary hiatus in Texas and Arkansas, is within the Mooreville Mooreville Formation of Mississippi and Alabama (Sohl, Formation of the eastern Gulf Coast. The Santonian­ 1964). Campanian boundary is within the Eutaw Formation of The type sections of the Santonian and Campanian Mississippi and the lower Mooreville Formation of central Stages were first described in 1856 and were named in 1857 Alabama. The Arcola Limestone Member of the Mooreville (Coquand, 1856, 1857). Microfossils from these stratotypes Formation, previously used as a marker bed for the Austinian-Tayloran boundary in the eastern Gulf Coastal have been studied by many workers (e.g., Van Hinte, 1968; Plain, lies well within the Tayloran Stage and appears to be Goharian, 1971; Barr, 1972; Seronie-Vivien, 1972; Sis­ time transgressive. singh, 1977; Verbeek, 1977). The results of these studies have refined the limits of the stages and made correlations with other areas of the world more precise. Published data suggest that the Santonian-Campanian boundary falls within INTRODUCTION the Eutaw Formation of Mississippi and Alabama (Young, 1963; Smith, 1975; Russell and others, 1982). This inter­ pretation needs more complete documentation based on Purpose and Scope detailed sampling. About 50 samples from three outcrop The Austinian-Tayloran provincial Stage boundary of localities and two cores (fig. 1) were examined for the the U.S. Gulf Coast has been considered correlative with purpose of documenting both the Santonian-Campanian and the Santonian-Campanian Stage boundary; however, this Austin ian-Tayloran Stage boundaries by means of calcare­ has not been universally accepted (Young, 1963; Hazel, ous nannoplankton, foraminifers, and ostracodes. 1977). The Upper Cretaceous Eutaw Formation and Moore­ ville and Demopolis Formations of the Selma Group of Acknowledgments Mississippi and Alabama represent an ideal test for docu­ menting both the Santonian-Campanian and the provincial I appreciate the thoughtful reviews of W. V. Sliter, Austinian-Tayloran Stage boundaries in the eastern Missis­ Page Valentine, N.F. Sohl, and J.E. Hazel. I thank N.F. sippi embayment. Sohl, J.E. Hazel, and C.C. Smith for helpful discussions In the east Texas embayment, the Austin ian-Tayloran regarding the Mesozoic stratigraphy of the Gulf Coastal Stage boundary usually occurs at a distinctive lithostrati­ Plain. graphic contact. The Austinian and Tayloran provincial Stages were formally defined by Murray (1961). Long before this, however, Gulf Coast geologists were attempt- STRATIGRAPHY Three Upper Cretaceous marine formations have been Manuscript approved for publication February 10, 1989. investigated in the research area. They are, from oldest to Stratigraphy I AREA OF ENLARGEMENT EXPLANATION I ~ DEMOPOLIS FORMAT~N I ~MOOREVILLE FORM!TION • EUTAW FORMATION 0 10 20 30 40 Miles I I I I I 11 I I I 0 10 2-0 30 40 Kilometers Figure 1. Sample sites and generalized distribution of Upper Cretaceous formations in Alabama and Mississippi. youngest, the Eutaw Formation, the Mooreville Formation, Eutaw Formation and the Demopolis Formation. The geographic and strati­ graphic distribution of the Eutaw, Mooreville, and Demo­ The Eutaw Formation is separated into lower "typi­ polis Formations is shown in figures 1 and 2. The strati­ cal" beds and the upper Tombigbee Sand Member. The graphic distribution of samples analyzed and an idealized lower unit is campo ed of glauconitic fine- to medium­ lithology of the localities investigated are shown