Kansas Geological Survey, Bulletin 204, pt. 1, originally published in 1972
Originally published in 1972 as part of Kansas Geological Survey Bulletin 204, pt. 1, p. 27-28. This is, in general, the original text as published. The information has not been updated.
A survey of a core from the Atlantic Oil Company No. 1-A Mark well (C SE SE sec. 28, T. 20 S., R. 33 W.), Scott County, Kansas, has revealed endothyroid foraminifera of Meramecian (late Mississippian) age. Endothyra symmetrica, E. spiroides, and E. macra have been identified from a foraminiferal limestone at 4991 feet. E. spiroides is a zone marker for rocks equivalent in age to the Salem Limestone.
Preliminary studies reveal that endothyroid foraminifera are plentiful and sufficiently well preserved to be used for stratigraphic correlation of subsurface rocks in Kansas. Specimens of endothyroids, both free and in thin sections, have been obtained from a core from the Atlantic Oil Company No. 1-A Mark well in Scott County, Kansas. The endothyroids present indicate a Meramecian (late Mississippian) age for that part of the core in which they occur. The Meramecian Stage is made up, in ascending order, of the Warsaw Limestone, Salem Limestone, St. Louis Limestone, and Ste. Genevieve Limestone. Heretofore, correlation of the subsurface Mississippian in Kansas was made on the basis of lithology or electric logs, and the presence of the key Salem Limestone (oolitic) was universally based upon the occurrence of "Endothyra baileyi," which is prolific in the oolite of the type section of the Salem (= Bedford, Spergen) Limestone in Washington County, Indiana. The No. 1-A Mark was chosen for this investigation because Lee (1940) stated that fossils of definite St. Louis age were present in this well (see Girty, 1940), and because of subsequent age determination of part of this core by Thompson and Goebel (1969) on the basis of the occurrence of conodonts.
Members of the endothyroid group, to which "E. baileyi" belongs, are now known to range from middle and upper Devonian well into the Pennsylvanian. They comprise more than six genera occurring in rocks of equivalent age throughout the world--in Russia, China, Japan, England, Belgium, Canada, Australia, Indochina, France, Spain, Ireland, Germany, Brazil, Turkey, Wales, Rumania, Morocco, Algeria, Laos, and Alaska. Endothyroid foraminifera have become the valuable zone markers for Mississippian beds in world-wide stratigraphic correlation that the fusulinids are for Pennsylvanian and Permian strata.
Three species have been identified among the free specimens extracted from a foraminiferal limestone from 4991 feet in the No. 1-A Mark well: Endothyra symmetrica, E. macra, and E. spiroides, all found in Mississippian rocks of the Great Basin (Zeller, 1957). The planispiral endothyroids make up about 75 percent of the limestone. Plectogyroid forms and the large planispiral Tournayella are not abundant. The microfauna from 4756 to 5111 feet contains E. symmetrica, E. macra, "Plectogyra sp.," Tournayella sp., Ammodiscus sp., Archaediscus? sp., and Calcisphaera sp.
E. symmetrica E. J. Zeller, illustrated in Figure 1, is approximately 0.83 mm in diameter, with a large proloculus of 80.16 μ. It has no hook in the final chamber and contains no secondary deposits. The coiling shows a nearly uniform rate of expansion, and the septa are strongly anteriorly directed. It has four volutions, the septal count per volution (from last to first) being 10, 10, 10, 7.
Figure 1--Endothyra symmetrica E. J. Zeller. A, Horizontal axial section (KUMIP 2,013,808); B, vertical axial section (KUMIP 2,013,809); X 111; 4991 feet, Atlantic Oil Company No. 1-A Mark core, C SE SE sec. 28, T. 20 S., R. 33 W., Scott Co., Kansas. [Note: images enlarged for web viewing and magnification recalculated.]
E. macra E. J. Zeller, illustrated in Figure 2,A-B, is approximately 1 mm in diameter and has a proloculus size of about 50 μ. It has a hook in the final chamber and secondary deposits are slightly developed. The first two volutions are much more tightly coiled than the succeeding volutions. The septa are medianly directed and arching. One of the larger specimens of E. macra contains four and one-half volutions, and the septal count per volution is (last) 11, 10, 9, 6, 3.
Figure 2--Endothyra macra (A-B) and E. spiroides (C) from core at 4991 feet in Atlantic Oil Company No. 1-A Mark well, C SE SE sec. 28, T. 20 S., R. 33 W., Scott Co., Kansas. A-B, E. macra E. J. Zeller. A, Vertical axial section (KUMIP 2,013,810); B, horizontal axial section (KUMIP 2,013,811); X 95. C, E. spiroides E. J. Zeller. Horizontal axial section (KUMIP 2,013,812), X 95. [Note: images enlarged for web viewing and magnification recalculated.]
E. spiroides E. J. Zeller, illustrated in Figure 2,C, is approximately 1.03 mm in diameter, with a relatively small proloculus of 46 μ, although it is not certain that this section is exactly through the proloculus. Distinctive characters of E. spiroides are its slightly ovoid method of coiling, which is rather rapidly expanding, and chambers that show almost no swelling between the sutures. There is a hook in the final chamber, but there are no other secondary deposits. The septa are slightly anteriorly directed. This species contains five volutions, and the septal count is (last) 12, 12, 10, 7, 4.
E. symmetrica is early Meramecian in age and may range upward into the Chesteran. E. spiroides is a valuable zone marker because of its widespread occurrence and short stratigraphic range. Zeller (1957) correlated the Endothyra spiroides Zone in the Cordilleran area with lower Meramecian beds in the Midcontinent region, stating that this Zone contains a microfauna which is similar in many respects to that of the Salem Limestone of Indiana. The foraminiferal limestone at 4991 feet in the Mark No. 1-A well is equivalent in age to the Salem Limestone on the basis of the occurrence of these endothyroid foraminifera.
I wish to thank W. R. Van Schmus, Department of Geology, The University of Kansas, for aid in photographing the specimens, and R. L. Kaesler and E. J. Zeller, also of the Department of Geology, for helpful advice and review of the manuscript. The figured specimens are housed in the collections of the Museum of Invertebrate Paleontology, The University of Kansas, Lawrence, Kansas.
Girty, G. H., 1940, Report on fossils of Mississippian age from well cores in western Kansas; in, Subsurface Mississippian rocks of Kansas, by Wallace Lee: Kansas Geol. Survey, Bull. 33, p. 97-112. [available online]
Lee, Wallace, 1940, Subsurface Mississippian rocks of Kansas: Kansas Geol. Survey, Bull. 33, 114 p. [available online]
Thompson, T. L., and Goebel, E. D., 1968 , Conodonts and stratigraphy of the Meramecian Stage (Upper Mississippian) in Kansas: Kansas Geol. Survey, Bull. 192, p. 1-56. [available online]
Zeller, E. J., 1957, Mississippian Endothyroid Foraminifera from the Cordilleran Geosyncline: Jour. Paleontology, v. 31, no. 4, p. 679-704, pl. 75-82.
Kansas Geological Survey, Endothyroid Foraminifera from Subsurface Mississippian in Kansas
Placed on web May 8, 2009; originally published in March 1972.
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