Vicksburg (Oligocene) Smaller Foraminifera From Mississippi GEOLOGICAL SURVEY PROFESSIONAL PAPER 241 Vicksburg (Oligocene) Smaller Foraminifera From Mississippi By RUTH TODD GEOLOGICAL SURVEY PROFESSIONAL PAPER 241 Descriptions and illustrations of smaller Foraminifera from jive measured sections in western Mississippi UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1952 UNITED STATES DEPARTMENT OF THE INTERIOR Oscar L. Chapman, Secretary GEOLOGICAL SURVEY W. E. Wrather, Director For sale by the Superintendent of Documents, U. S. Government Printing Office Washington 25, D. C. Contents Page Abstract _________________ 1 Systematic descriptions— Continued Introduction ______________ 1 Family Heterohelicidae- _______ 24 Stratigraphic sections _ _____ 2 Family Buliminidae.-__________ 25 Systematic descriptions_ 4 Family Rotaliidae-___________ 34 Family Textulariidae___ 4 Family Amphisteginidae------- 42 Family Verneuilinidae__ 5 Family Cassidulinidae- _ __--___. 42 Family Valyulinidae _ _ 6 Family Chilostomellidae-______ 43 Family Miliolidae. ____ 6 Family Globigerinidae--------- 43 Family Ophthalmidiidae 10 Family Anomalinidae_________ 44 Family Lagenidae____ 10 Family Planorbulinidae__ 46 Family Polymorphinidae 16 Bibliography __ ___________________ 47 Family Nonionidae. ____________________________ 21 Index.___________--_------_-____ 49 Illustrations Plate 1. Textulariidae, Verneuilinidae, Valvulinidae, Miliolidae, Ophthalmidiidae__--_----------_----_-------_ 2. Lagenidae______--____________________-_______________________________-___-------_-------_-- 3. Polymorphinidae, Nonionidae_________________________________________________-_-----_----_---- 4. Heterohelicidae, Buliminidae_________________________________________________________________ Following Index 5. Rotaliidae___________________________________________________________________________________ 6. Rotaliidae, Amphisteginidae, Cassidulinidae, Chilostomellidae, Globigerinidae, Anomalinidae, Planor­ bulinidae-_______-_-________________________________________________--__--__-----------_-- Insert Distribution and relative abundance of Foraminifera in five Vicksburg Oligocene sections in Mississippi. Facing page 4 in VICKSBURG (OLIGOCENE) SMALLER FORAMINIFERA FROM MISSISSIPPI By RUTH TODD ABSTRACT area. The deposition of the Glendon limestone mem­ This paper describes and illustrates a fauna of 176 species ber was in deeper water with less clastic material. and varieties of smaller Foraminifera from parts of the Vicks- The five sections from which Mr. Monroe collected burg group, and charts the distribution of the species found are located as follows: (1) Mint Spring Bayou, near in five measured sections in central and western Mississippi. Vicksburg, Miss.; (2) Burke Creek; (3) Gulf and Ship The stratigraphic units involved are the Mint Spring marl mem­ ber of the Marianna limestone, the Glendon limestone member, Island Railroad cut 1.5 miles south of Plain; (4) Rich- and the marl member of the Byram formation. Thirteen new land Creek; and (5) Robinson Quarry near Brandon, species and three new varieties are described. Rankin County, Miss. These sections include, from bottom to top, the Mint Spring marl member of the INTRODUCTION Marianna limestone, the Glendon limestone member, A study of the smaller Foraminifera in samples col­ and the typical marl member of the Byram formation, lected by W. H. Monroe from five richly fossiliferous although not all are present in a single section. sections in the Vicksburg group (Oligocene) of Missis­ Fifty-seven samples were prepared and examined. sippi was made to see if definite correlation could be In the first two sections studied, all the samples were established from one section to another by means of prepared, but as the hard limestone beds yielded very these organisms. The results of the study are presented few specimens or none, in the other three sections only here. Additional material from other sections in the the softer beds, marls or clays or sands, were prepared. Vicksburg group would make a more complete and About two ounces of material was washed through 40-, possibly somewhat altered picture. In present circum­ 80-, and 200-mesh silk screens and, after drying, the stances it seems advisable to complete the present work, two finer portions were treated with carbon tetra- which may be useful as a basis for more detailed studies chloride that floated off most of the smaller Forami­ of the smaller Foraminifera in the Vicksburg group. nifera. The coarser portion was examined for large The general stratigraphic section exposed in western specimens and the sinkings of the other two portions Mississippi is as follows: were also examined for specimens which might not have floated. The picking was not done quantitatively, but an attempt was made to find all the recognizable forms Bucatunna clay member present and a rough estimate made as to abundance, whether rare, common or abundant. One hundred Byram formation Marl member seventy-six species and varieties were recognized, of Middle Oligo­ which thirteen species and three varieties are described cene (Vicks­ Glendon limestone mem­ as new. Eight others may be undescribed, but avail­ burg group ber restricted) able specimens do not warrant description. A few other forms were omitted because specimens were too few or Limestone member poorly preserved. Marianna lime­ stone The richest sections are those at Mint Spring Bayou Mint Spring marl member and at Burke Creek: 149 species and varieties occur in the former and 148 in the latter, with 135 common Lower Oligo­ Forest Hill sand (equivalent of Red Bluff clay to both. These two sections show the closest resem­ cene to eastward) blance and differ from the other three sections in the relative abundance of Miliolidae, 21 species of which The Forest Hill sand represents deltaic deposition with occur in these two sections in comparison with only a the landmass toward the northwest, and its equivalent single species of this family, MassiUna decorata Gush- Red Bluff clay to the eastward represents the marine man, in each of the other three sections. These three beds offshore from the delta. At the beginning of eastern sections together have 136 species and varieties, Vicksburg deposition, the Forest Hill deltaic deposits 85 of which are common to all three. Eighty species were submerged, permitting marine waters to cover the and varieties are common to all five sections. VICKSBURG (OLIGOCENE) SMALLER FORAMINIFERA FROM MISSISSIPPI The distribution chart (p. 4), showing the occur- STRATIGRAPHIC SECTIONS ence and relative abundance of all the species in each The five sections are described below, with the strati- sample studied, indicates the close relationships of graphic zones numbered upward from the bottom. the five sections. The foraminiferal fauna here described is a com­ Mint Spring Bayou, south of National Military Cemetery, posite one drawn from parts of all five sections. The Vicksburg, Miss. fauna of the lower part of the Vicksburg group would Byram formation. Thickness Marl facies. Ft. in. be expected to be one characteristic of nearshore and 20. Yellow laminated marl to road.________ ? shallow water conditions, and the entire section of near­ 19. "Ironstone".-________________ Crust ly 40 feet at Mint Spring Bayou and the lower part of 18. Harder blue and gray marl. Top ledge the section at Burke Creek, the most westerly of those in creek. Overlain by ironstone (?) _ _ 2 17. Blue marl----_-----_-___-_-_--______ 2 in Eankin County, does bear out this expectation. With 16. Hard gray glauconitic marL.__________ 2 the coming of deeper water in Glendon time, the 15. Gray glauconitic marl______________ 3 foraminiferal fauna shows a corresponding change in 14. Cream-colored marl, somewhat harder than bed 13_--_--_________________ 2 certain of its species, chiefly those belonging to the 13. Glauconitic marl___---_______________ 1 Miliolidae. The foraminiferal fauna as a whole, how­ 12. Soft shaly limestone__-----___-_______ 2 lib. Laminated marl and sand] ever, appears to be a single fauna with no distinct 1 la. Laminated marl and sandj ------------ changes, other than the ecologic change from shallow, 10. Hard gray lime-_-------_____________ 1 nearshore deposition of the lower beds to deeper, off­ 9. Soft yellow marl-__-_____________-___ _____ 10 shore deposition of the upper beds. From the fora­ Glendon (?) limestone member. miniferal evidence it appears that the entire section at 8. Hard blue-gray lime. Top of waterfall. _ 2 7. Hard gray marl____________________ _____ 10 Mint Spring Bayou is equivalent to the lower parts of 6. Gray, brown, and light blue marl with the sections in Eankin County. hard break in middle-______________ 2 10 From the study of the distribution and abundance of 5. Hard gray lime--...____________ 2 10 4. Soft gray fossiliferous calcareous marl or the Foraminifera in these sections, the following species clay. —— ———— __________________ _____ 5 and varieties appear to be of significance and may be 3. Hard gray lime-------___-_-----_--__ 2 found useful in local correlation work elsewhere in this Marianna limestone. Mint Spring marl member. part of the Vicksburg group. 2. Gray and brown sand and clay. Fossils. Massilina decorata Cushman Gray, highly calcareous sand at top__ 10 Bulimina ovata D'Orbigny var. primitive/, Todd, n. var. 1. Blue-gray, carbonaceous sand and clay. Umgerina mcJcsburgensis Cushman and Ellisor Fossils———__ —— ____________ 7+ Angulogerina byramensis (Cushman) var. anfracta Todd,