Carboniferous Megafaunal and Microfaunal Zonation in the Northern Cordillera of the


Carboniferous Megafaunal and Microfaunal Zonation in the Northern Cordillera of the United States By WILLIAM J. SANDO, BERNARD L. MAMET, and J. THOMAS DUTRO, JR.



A comparison of a %onal scheme based on and with foraminiferal %onatio.n in the rocks of Montana^ W^yoming, Idaho, and


GEOLOGICAL SURVEY William T. , Director

For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 - Price 75 cents (paper cover) CONTENTS

Page Page Abstract______El Comparison of zonation schemes Continued Introduction ______1 Identification in different depositional provinces.___ E19 O Purpose and scope-___--___-____-____--_-_-______- _w Correlation of zone boundaries....-.-_.__-_ 19 - zonation______5 Post-Madison hiatus.______20 Historical development.______5 Absence of other gaps in the record.______20 Distribution, composition, and criteria for recogni­ Intracontinental and intercontinental correlations. 20 tion. ______5 Lodgepole ..______-__----_--_-- 20 Limitations.______11 Mission Canyon Limestone-______--- 22 22 Foraminiferal zonation.______12 Little Flat Formation.______Monroe Canyon Limestone. ______22 Historical development.______12 Amsden Formation ______23 Distribution, composition, and criteria for recogni­ Big Snowy Group______-____ 23 tion....-.-.-..------... ______13 Conclusions.______23 Limitations.______17 23 Comparison of zonation schemes.______17 References cited.______Integrity of superposition______17 Index.______27


Page PLATE 1. Stratigraphic diagram showing positions of foraminiferal samples in stratigraphic sections, northern Cordilleran region. ______In pocket FIGURE 1. Map of northern Cordilleran region, showing location of stratigraphic sections and boundaries between Mis- sissippian depositional provinces. ______E2 2-6. Charts: 2. Historical development of megaf aunal zonation in the northern Cordillera______6 3. Ranges of significant coral taxa in megafaunal zones of the Mississippian in the northern Cordillera- __ 7 4. Ranges of significant brachiopod taxa in megafaunal zones of the Mississippian in the northern Cordil­ lera ______8 5. Ranges of significant Cordilleran foraminiferal taxa in Mamet Carboniferous zonation scheme ______14 6. Ranges of northern Cordilleran foraminiferal samples in the Mamet zonation scheme for the Lower Carboniferous compared with megafaunal zone designations for the same samples. ______18 7. Correlation chart showing inferred relationships of faunal zones, principal European and American time- stratigraphic divisions, and Cordilleran and type Mississippian formations, ______21


Page TABLE 1. Register of localities E3




ABSTRACT America is a serious deterrent to precise time-strati- > mparison of a 12-zone biostratigraphic scheme based on graphic analysis. Purely lithostratigraphic techniques, «*i and brachiopods with, a 15-zone scheme based on for- currently popular in this country, are not an adequate irifers results in consistent chronostratigraphic correlations substitute for time-tested biostratigraphic methods. Be­ t"ie Mississippian of the northern Cordilleran region both Mn the Cordilleran basin and with the type Mississippian se- cause of the many diverse sedimentary environments T"e. Except for the Kinderhook (early ) interval, represented in the Mississippian of , it : -esolution of the foraminiferal zones is as fine or finer than seems unlikely that a single scheme of biostratigraphic t of the megaf aunal zones. A higher degree of cosmopolitanism zonation will ever prove to be satisfactory for the entire t 3 foraminiferal faunas makes them generally more useful . Moreover, no single group of seems to r megiafaunas for correlation with the type Mississippian " standard Carboniferous sequences in western Europe. hold the key to temporal relationships in all parts of ]] o following correlations of northern Cordilleran formations North America. A of zonation schemes, each based 'ndicated by both megafaunal and foraminiferal faunas. (1) on the distribution of many kinds of fossils in a partic­ ^ Lodgepole Limestone ranges in age from late Kinderhook to ular sedimentary basin or province, is a logical alternate irie Osage (pre-Burlington to earliest Keokuk). This age solution to the problem. Such an endeavor will g"i coincides approximately with the early and middle Tour- ^ : an (upper part of Tnl-Tn2) of western Europe. (2) The take many of careful study by teams of *=:ion Canyon Limestone ranges in age from middle Osage to biostratigraphers. 1;- Meramec (early Keokuk to middle Salem). This interval Two of the authors of this report (Sando and Dutro) approximately equivalent to the late Tournaisian (Tn3) to have devoted the better part of the past 10 years of their 1;- Visean (VI) interval of western Europe. (3) A widespread research to definition and testing of a zonation scheme t is with a minimum time span represented by the upper part t 3 (V2a of western Europe) separates based principally on corals and brachiopods for the t-Madison strata from the . (4) The Little Mississippian of the northern Cordilleran region, t Formation is of middle Meramec (early St. Louis) age encompassing parts of Idaho, Montana, Wyoming, and correlates with a part of the middle Visean (V2b and lower- Utah. The results of recent work by C. A. S'andberg and "t V3a) of western Europe. (5) The Monroe Canyon Lime- Gilbert Klapper on the distribution of in the ir. ranges in age from middle Meramec (late St. Louis) r^gh most of the Chester. This interval includes the late uppermost and lowermost Mississippian strata *an and early (V3a-E2) of western Europe. (6) in the same area have been incorporated in the zonation. : Amsden Formation of Wyoming ranges in age from Late Some of the zones have also been recognized and used sfssippian to . The oldest fossils found in by Helen Duncan and Mackenzie Gordon, Jr., in the , msden are of middle Chester age; late Chester fossils are Great Basin region of Utah. x present. (7) The of southwestern Montana x contains faunas of middle and late Chester age. Although the megafaunal zonation thus devised is useful in establishing relationships within the Cordil­ INTRODUCTION leran basin, important provincial differences in the T^e lack of a practical comprehensive of faunas make it difficult to correlate them precisely with ral zonation for the Mississippian 1 rocks of North standard stratigraphic units in the type area of the Mississippian. Moreover, relationships between the ""« Mississippian System of American usage includes the Lower 3rr»iferous and the lower part of the Upper Carboniferous of Euro- Mississippian-Pennsylvanlan boundary was originally placed at an * usage. It extends from the lower part of the Tournaisian to a , and Homoceras Zone cephalopoda have not been found tHn above the Eumorphoceras Zone of the Namurian. Opinion in the United States (Gordon, 1964, p. 83). However, recent unpublished rding the position of the Devonian-Mississippian boundary in studies of Mississippian in south-central Idaho by Mamet rica has fluctuated in a manner similar to that regarding the indicate the presence of foraminiferal faunas equivalent to the Homoceras ">rian-Carboniferous boundary in Europe (Mamet, 1968a). The Zone faunas of Europe. El E2 CONTRIBUTIONS TO PALEONTOLOGY

Cordilleraii zones and the classic marine Lower ­ 112° 111° 110° 109° 108° 107° iferous sequences of England and western Europe can 48' .15 be established only in very broad terms. The results of studies of Carboniferous Foraminifera by Mamet offer a possible solution to the difficulties encountered in cor­ MONTANA DEPOSIT1ONAL relating the megaf aunal zones outside the Cordilleran 13, '14 region. After having studied the Lower Carboniferous 47= foraminiferal sequences in the classic Tournai and Vise PROVINCE areas of Belgium, Mamet extended his work during the past ten years to England, , the U.S.S.E., and North Africa. Recently, he has been engaged in biostrat- igraphic studies in western Canada and in the area of 46' the type Mississippian in the United States. The out­ .11 .12 come of these studies is a scheme of 15 Lower Carbon­ iferous foraminif eral zones which can be recognized in appropriate f acies on a worldwide basis. .10 45' _ _ / _ _ MONTANA PURPOSE AND SCOPE WYOMING The purpose of this report is to present the results of a joint study of the zonation problem in the Missis­ MONTANA. sippian of the northern Cordilleran region. Approxi­ IDAHO mately 300 samples collected from stratigraphic sections WYOMING 44- zoned megaf aunally by Sando and Dutro were searched DEPOSITION AL for Foraminifera by Mamet by means of approximately N 500 thin sections. These samples were taken from the PROVINCE matrix of specimens used in megafaunal zone deter­ .9 .16 mination. One hundred and five samples from 20 strati- .17 graphic sections proved favorable for foraminif eral zone 43' \I 7 identification. LJ\I % 8 Locations of stratigraphic sections, shown in figure .18 1, are as follows: 1. Little Flat Canyon 2, NW% see. 20 and S% sec. 17, T. 7 S., R. 40 E., Bannock County, Idaho. 42° _9_ JJ 19." T] 2. Little Flat Canyon 1, SE% sec. 20, T. 7 S., R. 40 E., 4 20. Bannock County, Idaho. 50 100 MILES 3. East Canyon, NE% sec. 7, T. 9 N., R. 2 E., Cache County, Utah. 4. Old Laketown Canyon, Wi/2 sec. 32, T. 13 N., FIGURE 1. Map of northern Cordilleran region, showing loca­ R. 6 E., Rich County, Utah. tion of stratigraphic sections referred to ir text and 5. Sheep Creek, sec. 28 '(approx.), T. 1 N., R. 45 E., boundaries between Mississippian depositional provinces established by Sando (1967b). Bonneville County, Idaho. 6. Black Mountain, SE}4 sec. 23 and Wl/2 sec. 24, 12. Sacajawea Peak, Ni/2 sec. 27, T. 2 N., R. 6 E., T. 3 N., R. 43 E., Bonneville County, Idaho. Gallatin County, Mont. 7. Haystack Peak, sec. 19, T. 34 N., R. 117 W., Lincoln 13. Monarch-U.S. 89, sees. 22 and 27, T. 16 F., R. 7 E., County, Wyo. Cascade County, Mont. 8. Covey Cut-off, sec. 27, T. 34 N., R. 117 W., Lincoln 14. Dry Fork, sec. 36, T. 16 N., R. 7 E., Cascade County, County, Wyo. Mont. 9. Hoback Canyon, sec. 3, T. 38 N., R. 115 W., Teton 15. Little Chief Canyon, sees. 19 and 30, T. 26 N., County, Wyo. R. 25 E., Blaine County, Mont. 10. Baldy Mountain, sees. 26,27 and 35, T. 7 S., R. 3 W., 16. Dinwoody Canyon, NE% sec. 11, WWy± sec. 12, Madison County, Mont. Si/2 sec. 1, T. 4 N., R. 6 W., Fremont County, Wyo. 11. Logaii, sec. 25, T. 2 N., R. 2 E., Gallatin County, 17. Bull Lake Creek, SE% sec. 3 and Sy2 sec. 2, T 2 N., Mont. R 4 W., Fremont County, Wyo. CARBONIFEROUS ZONATION IN THE NORTHERN CORDILLERA OF THE UNITED STATES E3 18. Sinks Canyon (North), Ei/2 sec. 18, T. 32 N., zonal designation, plotted to on a stratigrapl ic E. 100 W., Fremont County, Wyo. diagram. 19. Buck Spring, NW% sec. 33, T. 23 N., E. 88 W., The aims of this paper are (1) to summarize the Carbon County, Wyo. coral-brachiopod zonation already established in the Mississippian sequences of Montana, Wyoming, Idaho, 20. Meadow Ranch, sec. 25, T. 22 N., E. 88 W., Carbon and Utah, (2) to establish equivalent Carboniferous County, Wyo. foraminiferal zonation in the same area, (3) to compare In table 1, the samples that form the basis of this the zonation schemes in order to test the internal study are listed by locality number; location of strati- validity of both approaches, and (4) to determine mere graphic section, stratigraphic position, and zonal precisely the ages of the zones in terms of the type designations are provided for each sample. Plate 1 Mississippian and standard sequences of the Car­ shows the positions of samples, each identified as to boniferous in western Europe.

TABLE 1. Register of fossil localities

USGS Local­ upper ity in Stratigraphic section Stratigraphie position Megafaunal Foraminiferal fig. 1 zone zone loc. No

6965 8 Covey Cut-off_-_- _ _ _ Amsden Formation, 250-260 ft above base ______K 17-18 (?) 16209 9 Hoback Canyon Amsden Formation, 117.8-119.8 ft above base. ._ . ___ K 18 16211 9 _ _ _do_____-_-_- _ _ Amsden Formation, 197.3 ft above base__- ______-_ _ ___ Pennsyl- post-18 vaman 16942 4 Old Laketown Canyon____ Lodgepole Limestone, 400-600 ft above base_ __ _._ Ct 7 16943 4 _ _ _do______Lodgepole Limestone, upper 2ft______.___ Ci 7 16950 4 _-___do__--___----__---._ Little Flat Formation, 39 ft below top______._ E 13 16951 4 _____do__-______Little Flat Formation, 12 ft below top______E 13 16953 4 ___-_do_-_-__--_-___-__._ Monroe Canyon Limestone, 6 ft above base___--_- .___ F 14 16954 4 _____do______Monroe^Canyon Limestone, 23-30 ft above base __ F 14 17360 11 Logan. _____ Lodgepole Limestone, 256-266 ft above base.. ______. B pre-7 17365 11 _____do_-______.__ Lodgepole Limestone, 348.8 ft above base______.__ .__ Ci 7 17377 11 _____do_-_-__---_-_-_---_ Mission Canyon Limestone, 19.7 ft above base _ _ _ _ _._ C2 8 17378 11 __--_do__--______Mission Canyon Limestone, 78.4 ft above base_-__- ____ _.- C2 8 17380 11 __ _ do______Mission Canyon Limestone, 269.2 ft above base______C2 8 17381 11 _____do______Mission Canyon Limestone, 322.9 ft above base__ _ _- C2 8 17383 11 _____do ______Mission Canyon Limestone, 523.8 ft above base. _ _ __. C2 9 17494 10 Baldy Mountain. Big Snowy Group, 255-280 ft above base ______..___ K 17-18(?) 17496 10 __.__do______Big Snowy Group, 367-379 ft above base. ___ K 17-18(7) 17498 10 ___..do_ _ Big Snowy Group, 437-447 ft above base _ .___ K i7-i8(?: 17848 7 Haystack Peak Lodgepole Limestone, 6 ft above base ______A pre-7 17849 7 ..____do______Lodgepole Limestone, 18-22 ft above base. ______.__ A pre-7 17855 7 ._-_ do_____ Lodgepole Limestone, 159-163 ft above base. _ ___ .___ B pre-7 17856 7 .___-_do______Lodgepole Limestone, 166-171 ft above base _ _ .___ B pre-7 17859 7 .___._do______Lodgepole Limestone, 178-183 ft above base. _ ___ .___ C_ 7 17860 7 __.__do. ______Lodgepole Limestone, 183-188 ft above base ______C_ 7 17879 7 ..____do______Mission Canyon Limestone, 0-30 ft above base... _ .___ C2 8 17882 7 ..._._do______.______Mission Canyon Limestone, 96-100 ft above base___ .___ C2 8 17902 7 ..____do______Mission Canyon Limestone, 544-568 ft above base __ _ D 10-11 17905 7 . ..do______._. ______Amsden Formation, 177-178 ft above base.-___- __. K 17 17906 7 .._..do______. ______Amsden Formation, 184-187 ft above base ______K 17 17907 7 ._-___do____.______Amsden Formation, 199-209 ft above base ______. K 18 17929 10 Baldy Mountain _ _ _ Lodgepole Limestone, 278.3 ft above base ______.___ Ci 7 17950 10 .___ _do__ _ Lodgepole Limestone, 575.3-578.3 ft above base_. ___ c, 7 17954 10 -__._do______Lodgepole Limestone, 699.3 ft above base______c, 7 17960 10 _____do______Mission Canyon Limestone, 348-368 ft above base_ ___ .__ C2 9 17964 . ___._do______Mission Canyon Limestone, 620.5-640.5 ft above base. _ _ . D 11 18634 2 Little Flat Canyon 1_ _ _ Lodgepole Limestone, lower 15 ft______._ A pre-7 18637 2 _ _ do______Lodgepole Limestone, 13-23 ft above base______.__ B pre-7 18645 2 .-____do______Lodgepole Limestone, 186-198 ft above base_ _ _ _ _._ C_ 7 18651 2 _____do__.______Little Flat Formation/28-32 ft above base _ pre-E 13-14 18655 2 -_--_do_____-______Little Flat Formation, 488 ft above base. __ _-___-----_ pre-E 13-14 18667 1 Little Flat Canyon 2. _ _ Little Flat Formation, 584 ft above base- ______E 13-14 18669 1 _--__do__- _ Little Flat Formation,|f597 ft above base. ___ E 13-14 18677 1 _____do ______Little Flat Formation, 761.5 ft above base _ __. E 13-14 18680 1 _____do______Little Flat Formation, 815 ft above base______._ _ _ E 13-14 E4 CONTRIBUTIONS TO PALEONTOLOGY

TABLE 1. Register of fossil localities Continued

USGS Local­ upper ity In Stratlgraphic section Stratigraphic position Megafaunal Foramlniferal Paleozoic fig. 1 zone zone loc. No.

18689 1 Little Flat Canyon 2______Monroe Canyon Limestone, 225.5-245.5 ft above base _ __ _ F 14 18699 1 __.__do______- Monroe Canyon Limestone, 407.5-412.5 ft above base. _ _ _ _ _ F 14-15 18700 1 _____do . . ______Monroe Canyon Limestone, 418.5-422.5 ft above base______F 14-15 18702 1 _-__.do_. ______Monroe Canyon Limestone, 460 ft above base______F 15 18703 1 --___do____--_----_-___ Monroe Canyon Limestone, 468 ft above base ______F 15

18704 1 _____do ______Monroe Canyon Limestone, 488-508 ft above base ______F 15 18705 1 do ______Monroe Canyon Limestone, 588-600 ft above base______pre-K 16i 18706 1 do __ Monroe Canyon Limestone, 613 ft above base ______pre-K 16i 18707 1 _____do-_____--_.______Monroe Canyon Limestone, 628 ft above base.. ______pre-K 16i 18708 1 _____do__--______Monroe Canyon Limestone, 63 8 ft above base ______K 16i(?)- 16s

18709 1 ___-_do______Monroe Canyon Limestone, 645-647 ft above base.______K 16s 18710 1 _____do______--_- Monroe Canyon Limestone, 661 ft above base. ______K 16s 18711 1 _____do__-______-_-_-__ _ Monroe Canyon Limestone, 688 ft above base ______K 16s-17 18715 1 _____do-_-____-____--__ . Monroe Canyon Limestone, 805-825 ft above base.. ______K 17-18 18720 1 ____.do______Monroe Canyon Limestone, 905 ft above base.. ______K 18

18721 1 _____do______- Monroe Canyon Limestone, 919-923 ft above base______K 18 20047 3 East Canyon______-. Brazer Limestone (as used by Mullens and Izett, 1964), 50 ft K 17 below top. 20059 6 Black Mountain. _.. __ _ Lodgepole Limestone, 227.5 ft above base. ______Ci 7 20064 6 _____do______.______Lodgepole Limestone, 340.5 ft above base _ ...... _ ... Ci 7 20065 6 do . Lodgepole Limestone, 355.5 ft above base______Ci 7 20067 6 _____do______.______Lodgepole Limestone, 402.5 ft above base ______Ci 7 2006S 6 _-___do_-______-___.___ _ Lodgepole Limestone, 404.5 ft above base. ______Ci 7 20070 6 _____do_____-______._ Lodgepole Limestone, 415.5 ft above base ___ __ .______Ci 7 20079 6 _____do----____-______. Lodgepole Limestone, 612.5-617.5 ft above base______Ci 8 20085 6 _____do_-_.______Lodgepole Limestone, 668.5-673.5 ft above base______Ci 8 20088 6 _____do______.______Mission Canyon Limestone, 35-38 ft above base______.___. C2 8 20089 6 _____do-______-____.__ _ _ Mission Canyon Limestone, 44-47 ft above base ______. C, 8 20100 6 _____dO___-_--____.____ _ Mission Canyon Limestone, 630-634 ft above base ______C2 9 20104 6 __.__do-_. ______Mission Canyon Limestone, 825.5-845.5 ft above base- _ _ _ D 10-11 20107 5 Sheep Creek ______Lodgepole Limestone, 196.5-200.5 ft below top______Ci 7

20106 5 ____-dO__-______--____ _ Mission Canyon Limestone, 101-118 ft above base ____ _ C2 8 20108 5 ____.do_____. ______Mission Canyon Limestone, 38-48 ft above base ______C2 8 20647 12 Saeajawea Peak ______Lodgepole Limestone, 251.5 ft above base______B pre-7 20652 12 do --. . . _ Lodgepole Limestone, 295.8-308.8 ft above base ______Ci 7 20653 12 _____do______-_-.______Lodgepole Limestone, 322.8-334.3 ft above base___------___ Ci 7 20666 12 do _ _ Lodgepole Limestone, 567.3 ft above base. ______. Ci 7-8 20673 12 _____do______--_-__. __ Mission Canyon Limestone, 51-52 ft above base ______C2 8 20675 12 _____do___._. ---__.____ Mission Canyon Limestone, 78-93 ft above base______C2 8 20678 12 _____do__---_----______Mission Canyon Limestone, 240-242 ft above base ______C2 9 20701 15 Little Chief Canyon. ______Lodgepole Limestone, 5 ft above base____--______---_--_. A pre-7 20708 15 _____do_-----_-_--_--__ _ _ Lodgepole Limestone, 182- 187 ft above base. ______c, 7 20710 15 _____dO-_-__--_-.______Lodgepole Limestone, 204-205 ft above base__-______Ci 7 20716 15 ____-do__-______.___ _ Lodgepole Limestone, 189-205 ft above base______c, 7 20730 15 _____do___--______- Lodgepole Limestone, 439.7-442.7 ft above base______c, 7 20740 15 do _ Mission Canyon Limestone, 30-35 ft above base______C2 8 20743 15 do Mission Canyon Limestone, 280 ft above base ______C2 8 20751 14 Dry Fork______Lodgepole Limestone, 1.5 ft above base ___--___-____-- _ _ A pre-7 20771 14 _do______Lodgepole Limestone, 290.5-293.5 ft above base ______Ci 7 20787 14 _____do___.______Lodgepole Limestone, 66 1-669.5 ft above base- ______G! 7 20795 14 do __ Mission Canyon Limestone, 70-75 ft above base- ______C2 8 20798 13 Monarch-U.S. 89______Mission Canyon Limestone, 281.2-286.2 ft above base____ C2 9 20799 13 _____do-_------_--_ __ Mission Canyon Limestone, 309.2 ft above base__-___- _____ C2 9 20804 13 ___ do_-_-__-_ ____ . _ Mission Canyon Limestone, 617.2 ft above base______D 10 20805 13 _____do______Mission Canyon Limestone, 695.2-696.2 ft above base. _ _ __ D 10 21647 18 Sinks Canyon (North) __ Madison Limestone, 197-200 ft above base ______C2 9 21648 18 _-__-do_-______.______Madison Limestone, 242.5-250.5 ft above base______C* 9 21677 17 Bull Lake Creek___ _ _ Madison Limestone, 656.5-659.5 ft above base______D 10-11 21692 16 Dinwoody Canyon______Madison Limestone, 792.5-807.5 ft above base. ______D 10-11 21725 19 Buck Spring _ Amsden Formation, 140.5-142.5 ft above base_ _ _ __ Penn.? post- 18 21729 20 Meadow Ranch. _ _ _ Amsden Formation, 92.5-95.5 ft above base. ______Penn. post- 18 CARBONIFEROUS ZONATION IN THE NORTHERN CORDILLERA OF THE UNITED STATES E5 CORAL-BRACHIOPOD ZONATION recognition of a zonation (Klapper, HISTORICAL DEVELOPMENT Sandberg and Klapper, 1967) and inclusion of th. ,se beds in the Madison. It became apparent that the Lower The present scheme of megafaunal zonation had its / wenulata Zone of Klapper (1966) and origin in biostratigraphic studies of the Madison Group Sandberg and Klapper (1967) coincided with Zone A begun in 1954 by Sando and Dutro, who were assigned of Sando and Dutro (1960). The conodont work aho this research project in support of general geologic in­ resulted in definition of two zones, Siphonodella sand- vestigations by the U.S. Geological Survey in the north­ bergi-S. duplicata Zone and 8. sulcata Zone, for the ern Rocky Mountain region. Studies of nine strati- earliest Mississippian beds beneath Zone A. graphic sections in northeastern Utah, western Wyo­ ming, and Montana led to the recognition of five coral In a synthesis of Mississippian stratigraphy in the zones (A, B, Ci, C2, and D) for the Madison Group and northern Cordilleran region, Sando (1967b) presented Brazer Dolomite (Sando and Dutro, 1960; Sando, 1960) a composite zonation of the entire Mississippian inter­ (fig. 2). The Madison coral zonation was subsequently val. A sequence of 12 megafaunal zones incorporated all applied to stratigraphic problems in northwestern Mon­ the previous work discussed above. Two major cycles of tana (Mudge and others, 1962) and central Wyoming sedimentation were recognized, Madison cycle and a (Sando, 1967a). This zonation concept has also been later, post-Madison cycle, separated by a widespread used extensively since 1960 in unpublished reports to episode of epeirogenic uplift. The Madison interval was Geological Survey field geologists on numerous collec­ divided into the five zones of Sando and Dutro (1960) tions from many localities in the northern Cordilleran plus a newly-recognized pre-A Zone at the base, pro­ region. posed to include the cul conodont fauna of Klapper Study of the Mississippian sequence in the Chester- (1966). The post-Madison interval included six zores fied Range, southeastern Idaho, led to the recognition of that began with a newly recognized pre-E Zone fol­ three coral zones (E, F, and K) and four braehiopod lowed by coral zones E and F of Dutro and Sando zones in post-Madison Upper Mississippian strata (1963a). A newly recognized pre-K Zone based on (Dutro and Sando, 1963a). One of these coral zones and brachiopods was delineated above Zone F. Thence fol­ two of the brachiopod zones were also identified in beds lowed Zone K of Dutro and Sando (1963a), which was of Late Mississippian age in western Wyoming and in turn overlain by a newly recognized post-K Zone southwestern Montana (Dutro and Sando, 1963b). The based on brachiopods. This 12-zone megafaunal system coral zonation recognized in these areas is very similar is the one used in the present report. to the scheme developed earlier by Parks (1951) for DISTRIBUTION, COMPOSITION, AND CRITERIA FOR the Upper Mississippian sequence in northern Utah. RECOGNITION The three coral zones have been tested subsequently in unpublished reports to Geological Survey geologists The zonation scheme embodies both assemblage zone working in southeastern and south-central Idaho. and range zone concepts. With the exception of the Studies by Mackenzie Gordon, Jr., and Helen Duncan pre-A Zone, which is based 011 conodonts, the zoral (written comnmn., 1964) resulted in a zonation scheme, indices are genera and of corals and brachio­ based on corals and brachiopods, for the Osage-Chester pods. The ranges of significant zonal fossils are shown interval of the Great Basin area of Utah. In addition to in figures 3 and 4. The zones are identified by means of the E (Ekvasophyllum,) F (Faberophyllum), and K assemblages of these fossils in some occurrences and ( Oaninia) Zones of the Chesterfield Range, this scheme by means of individual taxa of restricted range in included three zones in the Upper Mississippian interval others. beneath Zone E, a pTs-Oaninia Zone between Zones F The oldest unit recognized in the zonation scheme is and K, and a post-Oaninia Zone of Chester age above the pre-A Zone, which includes the two cul conodcnt Zone K. Subsequent unpublished studies by Gordon zones (/Siphonodella sandbergi-S. duplicata Zone and established the presence of the post-Oaninia Zone in the S. sulcata Zone) of Sandberg and Klapper (1967). lower part of the Amsden Formation of central The conodonts occur in the upper tongue of the Cottcn- Wyoming. Canyon Member of the Madison Limestone in When the original Madison coral zonation was pro­ central Wyoming and of the Lodgepole Limestone in posed (Sando and Dutro, 1960), noncoralliferous beds southern Montana. (See Klapper, 1966, and Sandberg of earliest Mississippian age were included in the sub­ and Klapper, 1967, for detailed discussions of the cono­ jacent, predominantly Devonian formations. Subse­ donts and distribution of these beds.) The upper part of quent detailed studies of these strata and their conodont the pre-A Zone is characterized by the assemblage of faunas by C. A. Sandberg and Gilbert Klapper led to Siphonodella sandbergi, S. duplicata, and Pseudopoly- 330-481 69 2 E6 CONTRIBUTIONS TO PALEONTOLOGY

Gordon and Sando and Dutro and Sandberg Parks Mudge, Sando Dutro and Duncan Klapper Sando and Sando (1951) Dutro (1960); and Dutro Sando Sando Sando (1960) (1962) (written (1966) (1967a) Klapper (1967b) (1963a) (1963b) commun., (1967) 1964)

Montana, SW. Montana, SE. Idaho western SW. Montana Great northern Montana western and Northern NW. SE. and Central Utah Wyoming, Basin, Wyoming, and Wyoming and central and northern Montana Idaho western Utah western Wyoming Wyoming, and Utah Wyoming South Dakota northern Utah

Not Not Post- Post-K discussed discussed Cam ?a'a

Spirifer K K brazer- Caninia K

Sp infer bruzer- ianus

Pre- Pre-K Caninia Triplophyllites Not Not Not discussed discussed Lithostrotion discussed Striatifera u-kitneyi- brazeriana F. leathuniense Fabero- F F FabcrophyUum Striatifera phyllum occult um-

Ekvasophyllum Ekvaso- E E inclinatum Erhino- phylhim confhtis cf.E. Not Not altfrnatus discussed discussed A mania? Quadra- Rhnpalolasma Pre-E hirsuti- formis hirsutifornns



Cz C 2 Not discussed Homalo- C phyllites C Vesiculo- phyllum c, Ci Ci

Not 7 discussed



Lower Lower A A A Siphonodella Siphonodella A crenitlata. crenulata

Siphonodella, sandbergi- Not Not Not cu\ Not - S. duplicata Pre-A discussed discussed discussed fauna discussed Siphonodella swicata

FIGURE 2. Historical development of megafaunal zonation in the northern Cordillera. CARBONIFEROUS ZONATION IN THE NORTHERN CORDILLERA OF THE UNITED STATES E7


Post- K ;


g -S S d g 03 2 (fl

disoan Pre- K Q. S »_: 03 C .O ^ (J £J " * ^ 's 's ~ t§ ~2 ^ 5t r CJ ?S W) F | 8 1 I S e ° w "S

tsj S s- ' s; *S

S 4) ; Q. (A O s ^ 1 2 s §* E 'TC « S -^ ir -^ ^ ^o** 0.^^:0.^X -2 ° ^ * §en^^-S -^ *S £ ^> "^ -S* Q. -^i co *^ ^ Si 13 ^i^-'sB "I'll ^ "»?l^£a S^.^xd^'^^J

Pre- « a -2§'l'=.-~J l 5 ^E c; '|1 N Ct' E £ 5 a .? -f J -5 1 -? ^ ° '5 8 r« 's *j

^ ? " "a. C^^^-IK?'^^ ~ g .£ -~ ~ |S^"so^l^:a. D "^ | ^ 1 1 l^ll^.^ ^ ^ 1 (§ ; n.°'? D;'-iS

OI M^ ~ >-d ^ i-S* 1^ 1K C2

' S at C o ; "S

||| | c, c "a, C 3 inso ^ d "5 t3 . ; i d .« ro "S > 2. B 0 C 3 £ 'S 0, ^ £;


Pre- A

FIGURE 3. Ranges of significant coral taxa in megafaunal zones of the Mississippian in the northern Cordillera. Solid range lines indicate common to abundant occurrences; dashed lines denote rare occurrences. oo

FIQUEE 4. Ranges of significant braehiopod taxa in megafaunal zones of the Mississippian in the northern Cordillera. Solid range lines indicate common to abundant occurrences; dashed lines denote rare occurrences. CARBONIFEROUS ZONATION IN THE NORTHERN CORDILLERA OF THE UNITED STATES E9 gnathus dentUineata. The lower part, known only from yon section in Montana (Mackenzie Gordon, Jr., Windy Gap in west-central Wyoming, is characterized commun., 1967). Zone A characterizes the lower 10-50 by Siphonodella sulcata. No brachiopods have been feet of the Paine Member of the Lodgepole found in the Cottonwood Canyon Member, but Syring- Limestone over a broad area in Montana, western Wyo­ pora occurs in the upper part at a few localities in ming, southeastern Idaho, and northeastern Utah. At central Wyoming. most localities, this interval is characterized by glau- Brachiopods from the upper part of the Sappington conitic crinoidal limestone. The zone has also been Member of the Three Forks Formation of southwestern provisionally identified in dolomitic beds above the Montana also are included in the pre-A Zone. Despite Cottonwood Canyon Member of the Madison Limestone recent detailed work on the of the in central Wyoming. Sappington (Rodriquez and Gutschick, 1967; Gut- In Zone B Amplexus is the most common coral, and schick and Rodriquez, 1967), the age and correlation Gyathaxonia^ Zaphrentites, and Palaeacis are rare, of parts of this unit remain controversial. Evaluation Among the brachiopods are RMpidomella aff. R. dimi­ of the Sappington fauna involves not only comparison nutiva Rowley, "" aff. "$." fiiplicoides Weller, of this fauna to Mississippi Valley faunas but also the Oleiothyridina cf. G. tenuilineata (Rowley), and question of whether the Louisiana Limestone is of "Spirifer" aff. "$." centronatus Winchell, which con­ Carboniferous or Devonian age, a problem that has not tinue into Zone B from subjacent strata. New elements been resolved to the satisfaction of all paleontologists in the brachiopod fauna include Gyrtina cf. "burlw.g- who have worked on the Louisiana Limestone faunas. tonensis Rowley, which is seemingly restricted to the Although a detailed discussion of the age and correla­ zone, and "Torynifer" cf. "TV' cooperensis (SwaHoy), tion of the Sappington is beyond the scope of this Orbinaria aff. 0. pyxidata (Hall), Retichonetes cf. paper, we provisionally believe that the Louisiana Lime­ R. logani (Norwood and Praten), Leptagonia cf. L. stone is of Devonian age and that the Carboniferous analoga (Phillips), land Brachythyris aff. B. suborbi- part of the Sappington includes units F, G, and H of cularis (Hall), which continue into superjacent beds. Gutschick and Rodriquez (1967, p. 601, fig. 1). Unit I Zone B corresponds approximately to the upper part of of Gutschick and Rodriguez is regarded as an extension the Paine Shale Member of the Lodgepole Limestone, of the upper tongue of the Cottonwood Canyon Mem­ which consists of poorly fossiliferous thin-bedded sT^y ber of the Lodgepole Limestone. Consequently, the prin­ and argillaceous limestone. The zone has been recog­ cipal elements of the brachiopod fauna that we include nized throughout the outcrop area of the Lodgepole in the pre-A Zone largely consist of undescribed species Limestone and is also present in the Allan Mountrin of Schuchertetta, "Oamarotoechia" "Ohonetes" "Rhy- Limestone of northwestern Montana. tiophora" "Unispirifer" "iSpirifer" Gomposita, and In Zone Ci, the principal coral indices are Cleisto- Syr ing o thyris. pora placenta (White), Michelinia expansa White, Zone A includes an assemblage of diminutive corals Lithostrotionella microstykim (White), and Rylstonia and brachiopods together with conodonts of the Lower cf. R. teres (Girty). Gleistopora appears to be restricted Siphonodella crenulata assemblage of Klapper (1966) to the zone, and the other elements occur only raroly and Sandberg and Klapper (1967). Among the corals, above it. Homalophyllites and Zaphrentites excavatus Metriophyllum cf. M. deminutivitm Easton and an un­ (Girty) begin their ranges at the base of the zone, and described species provisionally referred to Permia are Vesiculophyllum becomes abundant for the first time. restricted to this zone, and Gyathaxonia cf. O. tantUla Brachiopods that range into the zone from below Hit (Miller) and undescribed species of Palaeacis, Am- do not occur above it are "Spirifer" aff. "$." "biplicoides plexus, and Zaphrentites range into overlying beds. Weller, Oleiothyridina cf. O. tenuilineata (Rowle7), Vesiculophyllum occurs rarely in the zone in central "Torynifer" cf. "TV5 cooperensis (Swallow), Orbinana Wyoming. Brachiopods restricted to the zone include aff. 0. pyxidata (Hall), Retichonetes cf. R. logani (Nor­ "Spirifer" aff. "$." osagensis Swallow and a small wood and Pratten), and Leptagonia cf. L. analoga species of Orurithyris. Other common Zone A brachio­ (Phillips). Brachythyris aff. B. suborbicularis (Hall) pods are Rhipidomella aff. R. diminutiva Rowley, is known in subjacent and superjacent beds but is most "Spirifer" aff. "$." Mplwoides Weller, Gleiothyridina common in Zone Ci. The ubiquitous and long-ranging cf. G. tenuilineata (Rowley), and "Spirifer" aff. "$." "Spirifer" aff. "8." centronatus Winchell is also present. centronatus Winchell. are extremely rare A species of Nucleospira seems to be restricted to the in this assemblage; Pericyclus (Oaenocyclus) sp., zone. The zone is also characterized by a large assem­ Pericyclus (Rotopericyclus} sp., and Gattendorfia sp. blage of brachiopod species that appear for the first have been found at one locality, the Little Chief Can­ time and continue to the top of Zone C2. Among these E10 CONTRIBUTIONS TO PALEONTOLOGY are Imbreoda cf. /. forbesi (Norwood and Pratten), rence of the brachiopods Quadratia hirsutiformis (Wal- Ovatia cf. O. laev-icosta (White), "Dictyoclostus" cf. cott) and "Leiorhynchus" carboniferwni Girty. "Z>." viminalis (White), "Z>." cf. "Z>." ~burlingtonensis Auloprotonia, Rhipidomella arkansana Girty, and (Hall), "Spirifer" aff. "#." fooMj Hall, Spirifer cf. & Echinoconchus cf. E. alternatus (Norwood and Prat- logani Hall, the Spirifer aff. $. roioleyi-S. grimesi com­ ten) also occur in the upper half of the zone. Although plex, Punctospirlfer cf. P. solidirostris (White), "Pro- corals are generally very rare in this zone, a species of ductus" cf. "P." gallatinensis Girty, and Rugosochonetes Rhopalolasm-a has been found at several localities. Zone cf. ./?. loganensis (Hall and Whitfield). Other longer pre-E has been identified at several localities in south­ ranging elements are Diinegelasma sp. and Cleiothy- eastern Idaho and northeastern Utah in the lower part ridina cf. (7. obmaseima (McChesney). Zone Ci corre­ of the Deep Creek and Little Flat Formations, sponds approximately to the Woodhurst Limestone In Zone E the principal index fossil is the corrl genus Member of the Lodgepole Limestone. This zone has been Ekvasophyltum, which appears to be restricted to this identified in the upper part of the Lodgepole wherever zone at some localities but may range into the lov^er part the Lodgepole has been studied. Elements of the zone of the overlying Zone F. Other common corals in Zone are also present in the Allan Mountain Limestone of E are the species of LitJiostrotion (Siphonodendron) northwestern Montana and in the lower part of the called LitJiostrotion whitneyi by Meek, species of the Madison Limestone of central Wyoming. Dorlodotia-Pseudodorlodotia complex, Zaphrentites cf. The principal corals of Zone C2 are Zaplirentites ex- Z. spimdosus (Milne-Edwards and Haime), a snail un- cavatus (Girty), Homalophyllites, Vesiculophyllwin, described solitary coral provisionally referred to Zaph- and several species of . The brachiopod as­ rentites, and the tabulate coral Syringopora virginica semblage of this zone is dominated by the Zone Ci Butts, which may actually belong in the genus Ki'-echow- species of spiriferids and productids previously men­ pora. Palaeacis cuneiformis Haime occurs rarefr in the tioned. "Spirifer" cf. "$." madisonensis Girty seems to upper half of the zone. The principal brachiopods in be the only brachiopod species restricted to the zone. Zone E are Echinoconchus cf. E. alternatus (Norwood Zone C2 includes approximately the lower half of the and Pratten) and Orthotetes cf. O. Tcaskaskiensis Mission Canyon Limestone at all localities where the (McChesney), which range into the lower half of the Mission Canyon faunas have been studied. Elements of zone from below, and Anthracospirifer bifurcatus this zone also have been identified in the lower part of (Hall), which appears to be restricted to the lowa-r half. the Castle Keef Dolomite of northwestern Montana, in Other common brachiopods in the lower half are the lower half of the Brazer Dolomite of northeastern Brachythyris cf. B. subcardiiformis (Hall) and Oleio- Utah, and in the upper half of the Madison Limestone thyridina cf. O. obmajxima (McChesney), which are the of central Wyoming. only Madison fossils known to occur in the post-ftradison Zone D is characterized by the lowest occurrence of interval. Striatifera aff. S. brazeriana (Girty), a char­ fasciculate lithostrotionid corals, including Lithostro- acteristic Zone F brachiopod, occurs in the uppermost tion (Siphonodendron) oculinwn Sando and Diphy- part of Zone E in northeastern Utah. Zone E i? estab­ pfiyUutn sp. Other characteristic coral elements are lished on fossils that occur in the upper part of the CanadiphyUuml, Ankhelasma, Zaphrentites, Vesiculo- Little Flat Formation and the lowermost part of the phyllum, and Syringopora. Homalophyllites has been Monroe Canyon Limestone of southeastern Idsho and found in beds of Zone D at a few localities but is northeastern Utah and has also been identified in the characteristically a pre-Zone D index. Brachiopods are White Knob Limestone in south-central Idaho. generally rare, but Perditocardinia cf. P. dubia (Hall), Zone F is named from the coral genus Fdberophyllum, "/Spirifer" shoshonemis Branson and Greger, and whose range defines the limits of the zone. Oth?-r com­ Brachythyrisci.B.siibcardiiformis (Hall) are found at mon coral elements are species of the Dorlodotia- some localities. Zone D is the highest biostratigraphic Pseiidodorladotia complex, Zaphrentites? n. sp., and unit recognized in the Madison Group and equivalent Syringopora virginica Butts, which range into the strata. It is present in the upper half of the Mission zone from below. Species of DibunopJiyllmn and odd Canyon Limestone of Montana and western Wyoming, syringoporoids questionably referred to Syringopor- the Charles Formation of northeastern Montana, the ella are also common. Ekvasophyllum cf. E. inclinatwn uppermost part of the Sun River Member of the Castle Parks and LitJiostrotion (Siphonodendron) whitneyi Dolomite of northwestern Montana, the upper part of Meek may occur rarely in the lower part. Striatifera of the Madison Limestone of central Wyoming, and the aff. S. brazeriana (Girty), which ranges into Zone F upper half of the Brazer Dolomite of northeastern Utah. from below, is the principal brachiopod index. Anthra- Zone pre-E is characterized by the restricted occur­ cospirifer leidyi (Norwood and Pratten) is common in CARBONIFEROUS ZONATION IN THE NORTHERN CORDILLERA OF THE UNITED STATES Ell

the upper half, whereas Spirifer brazeriamis Girty is lems in the Mississippian of the Cordilleran region. rare. Zone F is known principally from the lower part There are many limitations to the usefulness of the of the Great Blue Limestone and Monroe Canyon Lime­ zonation as it is presently understood, and much work stone of southeastern Idaho and northeastern Utah and remains to be done to perfect the system. Some of the the White Knob Limestone of south-central Idaho. It problems are summarized below. has also been identified in beds referred to the Amsden Incomplete . Most of the faunas upon Formation by Klepper (Klepper and others, 1957) in which the zonation is based have been treated only super­ southwestern Montana. ficially from a taxonomic standpoint. Many decisions re­ Zone pre-K is a poorly f ossilif erous interval that has main to be made concerning the limits of species and been identified near the middle of the Great Blue Lime­ genera. The zones can be no more precise than the dis­ stone and Monroe Canyon Limestone of southeastern crimination of zonal indices. More detailed systematic Idaho. The limits of this zone are defined on criteria studies are necessary to sharpen the tools of biostrati­ that determine the top of the underlying F Zone and graphic discrimination. the bottom of the overlying K Zone. A few solitary Composite superposition. There is no single locality corals, possibly belonging to Zaphrentites, and the where 'all the megafaunal zones can be seen in super­ brachiopods AntJvracospirifer leidyi (Norwood and position. This circumstance has arisen because of a com­ Pratten), Spirifer brazerianus Girty, and Striatifera plicated history of sedimentation and epeirogenepis aff. 8. brazeriana (Girty) are the only fossils now during Mississippian time in the northern Rocky Moun­ known from this zone. tain region (Sando, 1967b). The complete zonal src- In Zone K, the principal index fossil is the coral cession, though necessarily composite, was established species Caninm ewcentrica (Meek). Other common coral after examination of many sequences of Mississipian taxa are Zaptirentites cf. Z. spinulosus (Milne-Edwards rocks, some of which provided key overlaps in various and Haime), Lithostrotionella cf. L. stelcJci Nelson, and parts of the Mississippian time interval. Nevertheless, the syringoporoids Syringoporellal and HayasaT&mai. the ultimate test of this zonation requires that it be com­ Caninm nevadensis (Meek) is also found in this zone pared with a suitable independent biostratigrapt ic at some localities. Zone K is also characterized by a standard. large assemblage of brachiopods. The principal brachio- Difficulties in identifying zone boundaries. Because pod elements are Spirifer brazeria/nus Girty, Antfira- the horizontal distribution of zonal indices is not uri- cospirifer leidyi (Norwood and Pratten), certain species form, the precise positions of zone boundaries are com­ of Diaphragm/us, and Anthracospirifer curvilateralis monly difficult to determine in any given stratigraphic (Easton). Other brachiopod species found in the Zone section. The lack of a continuous sequence of significant K assemblage will probably prove useful when more fossils at some localities may result in local uncertainties is known about their precise distribution. Zone K is a involving tens or hundreds of feet of section. At the?e widely distributed biostratigraphic unit that has been localities, arbitrary boundaries are recognized. A com­ identified at the top of the Great Blue Limestone and mon example is the boundary between Zones d andC2, Monroe Canyon Limestone of southeastern Idaho, in the which is difficult to place precisely at many localities but White Knob Limestone of south-central Idaho, in the which can be conveniently approximated by the con­ Amsden Formation of western Wyoming, and in the tact between the Lodgepole and Mission Canyon Lime­ Big Snowy Group of southwestern Montana. stones. Boundary indemnification can be improved only The highest Mississippian zone recognized in this by additional collecting in the poorly f ossiliferous inter­ paper is the post-K Zone based on unpublished brachio­ vals and by discovery of new fossils useful for identi­ pod studies by Mackenzie Gordon, Jr. The zone is pres­ fying the zones. ently recognized on the occurrence of Anthracospirifer Fades influences. Although environmental sensi­ weUeri (Branson and Greger) and an undescribed tivity of the organisms used in zonation has not proved species of Diaphragmus. Other potentially useful ele­ to be as important a factor as originally anticipated, ments of the brachiopod assemblage remain to be recognition of some of the zones in certain parts of the described. This zone has been identified in the Manning area studied has been made difficult because of facies Canyon Shale of southeastern Idaho and the Amsden changes. A good example is the lower part of the Madi- Formation of central Wyoming. ion Limestone of central Wyoming (Wyoming province of Sando, 1967b), where corals and brachiopods charac­ LIMITATIONS teristic of Zones A, B, and Ci of the Lodgepole Lime- The zonation scheme outlined above is by no means itone are greatly reduced in variety and numbers so ths.t intended as the final solution to biostratigraphic prob­ precise determination of zone boundaries has not been E12 CONTRIBUTIONS TO PALEONTOLOGY possible on the basis of available evidence. Similar diffi­ in the U.S.S.E. and western Europe since publication culties have been experienced in attempting to analyze of an important symposium by Kauzer-Chernoussova the Madison Group in subsurface sections in and near and others 1948, considerably less interest in this field the depositional center of the Williston basin of Mon­ has been shown by North American paleontologists. tana and North Dakota. Although some of the problems American attempts at zonation began with the pioneer may prove to be insurmountable, additional collecting study of Zeller (1950), who demonstrated that various in these poorly fossiliferous areas should resolve many parts of the Mississippian sequence in its type area could of the questions. be identified by means of evolutionary changes in the Difficulties in correlation with the type Mississip­ endothyroid faunas. Subsequently, Zeller (1957) pian. It became apparent early in the work on zonation published a study of 12 endothyroid sequences of Mis­ that many of the key fossils in the Cordilleran region sissippian age in the Cordilleran region in which he either were absent or had different vertical ranges in the recognized four widespread zones. Zeller found a close Mississippi Valley area. This is particularly striking in similarity between Cordilleran faunas and Mississippi the coral faunas but is less apparent among the brachi- Valley faunas in the Upper Mississippian, but experi­ opods. This provincialism has evoked a relunctance on enced difficulty in correlating the lower Missi?sippian our part to apply standard Mississippian time-strati- rocks of the two areas. graphic designations to the Cordilleran sections. Broad Woodland (1958) recognized three zones and one faunal similarities, particularly in the brachiopod subzone in the Mississippian of central Utah. Wood­ faunas, led to the following tentative correlations: Zones land's zonation scheme was similar to Zeller's in the pre-A, A, and B are approximately equivalent to the Osage-Meramec interval, but he also recognized a zone Mississippioii part of the Kinderhook Series; Zones Ci of Chester age not found by Zeller. Like Zeller, and C2 equate approximately with the Osage Series; Woodland was able to correlate readily the late Zones D, pre-E, E, and F represent approximately the Mississippian faunas with the Mississippi Valley area Meramec Series; and Zones pre-K, K, and post-K are but was uncertain about correlations in the Lower approximately equivalent to the Chester Series. Identifi­ Mississippian. Armstrong (1958, 1967) found that en­ cation of parts of the standard series in the Cordilleran dothyroid faunas are useful in differentiating rocks of region was based largely on arbitrary division of the Early Mississippian age from rocks of Late Mississip­ Cordilleran equivalents rather than on precise compari­ pian age in northern and central New Mexico. sons of parts of the faunal successions. For example, be­ Mamet (1962), having studied the Carboniferous cause the Zone D-Zone F interval equals the Mera­ Foraminifera of western Europe (Tournaisian, Visean, mec, Zone D is called early Meramec, Zone pre-E and E and Namurian type sections), was struck by the great are middle Meramec, and Zone F is late Meramec. More similarities1 among formaminiferal families observed in precise calibration of the megafaunal zones in terms of Europe and North America. He suggested that (1) the type Mississippian sequence requires checking these phylogenetic development of all the families i? identi­ conclusions against a system based on less provincial cal in Eurasia and North America, (2) there is no organisms than the ones used thus far. true provincialism in the northern hemisphere, and free Difficulties in congelation with Carboniferous stand­ communication persisted during most of the Lower ards. Although Hill (1948, 1957) and Moore (1948) Carboniferous, (3) a number of widespread taxa can recognized European stages (Tournaisian, Visean, and be traced all around the northern hemisphere, (4) pre­ Namurian) in the North American faunal succession cise correlation can be made between Eurasia ard North largely on the basis of corals, subsequent work in Europe America, (5) the Kinderhook is approximately of early and America has not produced a sharpening of the Tournaisian age, the Osage is middle to late Tournai­ resolution of these biostratigraphic tools. It is too soon sian, the Meramec is early to middle Visean, and the to pass judgment on the ultimate utility of corals and Chester is late Visean to early Namurian. brachiopods for intercontinental correlation because McKay and Green (1963) recognized four main much work remains to be done on these groups of fossils. successive range zones, two concurrent range zones, and However, available information does not permit the one assemblage zone in the Mississippian rocks of Al­ same level of biostratigraphic discrimination attained berta and attempted to correlate these rocks with the by means of cephalopods, conodonts, and foraminifers. type Mississippian and sections in the Western United FORAMINIFERAL ZONATION States by means of endothyroid faunas. Th<\y also HISTORICAL DEVELOPMENT pointed out that non-endothyroid genera were present Although Lower Carboniferous foraminiferal zona­ and might be useful as zone fossils. Studies of the dis­ tion has been the subject of much study and discussion tribution of foramanifers in the Eedwall Limestone of CARBONIFEROUS ZONATION IN THE NORTHERN CORDILLERA OF THE UNITED STATES F13 Arizona by Skipp (1963, 1964, 1969) led to the recog­ permit reliable identification of Zone 6 of Mamet a nd nition of six zones based on endothyroids and tournayel- Skipp (1969). This assemblage is found in the Paine lids and ranging in age from Kinderhook to late Shale Member of the Lodgepole Limestone in south­ Meramec. Skipp, Holcomb, and Gutschick (1966) eastern Idaho, western Wyoming, and Montana. summarized the known distribution of tournayellids in Zone 7 is characterized by the acme of Septaglovw- the Mississippian of North America. spiranella primaeva (Eauzer-Chernoussova, in Cherny- Mamet and Skipp (1969) presented a comprehen­ sheva), S. damae Lipina, and Rectoseptaglomospira- sive outline of foraminiferal zonation of the Mississip­ nella. Ohernyshinella (O. tumulosa Lipina), Septa- pian of North America. The distribution of all Early brunsiina, Palaeospiropleotarnmina, and Latiendothyra Carboniferous genera known in North America was are other, less abundant, elements. This assemblage is recorded, 14 assemblage zones were established, and the found in the Woodhurst Limestone Member of the standard units of the type Mississippian were corre­ Lodgepole Limestone in southeastern Idaho, northes st­ lated with their counterparts in the standard western ern Utah, western Wyoming, and Montana. European sections of the Lower Carboniferous. Mamet Zone 8 is recognized by the outburst of Tuberin- and Skipp's paper formed the foundation for the dothyra tuberculata (Lipina) and by abundant Septa- present work, which treats the occurrence of the foram­ glomospiranella primaeva (Eauzer-Chernoussova, in iniferal zones in the northern Cordilleran region in Chernysheva), Septabrunsiina parakrainica Skipp, more detail and compares the foraminiferal zonation Holocomb, and Gutschick, Calcisphaera laevis William- with the megafaunal scheme established for that area. son, and Latiendothyra. It is also characterized by the decline of Ohernyshinella and Rectoseptaglomospira- nella. This assemblage occurs mostly in the lower third DISTRIBUTION, COMPOSITION, AND CRITERIA FOR RECOGNITION of the Mission Canyon Limestone in southeastern Idaho, western Wyoming, and Montana. The foraminiferal zones recognized in this study are Zone 9 is characterized by numerous T wberendothyra part of a 19-zone system originally established on (T. tuberculata (Lipina)) and by the acmes of Spino- European and Asiatic faunal successions (Mamet, endothyra spinosa (Chernysheva), S. paracostifera 1965; Mamet, Mortelmans, and Sartenaer, 1965; Le- (Lipina, in Lebedeva and Grozdilova), S. bellicorfa grand, Mamet and Mortelmans, 1966; Mamet and Eeit- (Malakhova), and Carbonella. Tournayella, Septa- linger, 1969). Zones 1 through 5 in this scheme are tournayella^ Septaglomospiranella, and Septabrunsiina Upper Devonian (upper ) and will not be are also present. Eoforschia, Tetrataxis, Endothyra of discussed here. The earliest Tournaisian zone in the the group E. ? nordvikensis Lipina, Latiendothyra lati- type locality of the Tournaisian is Zone 6 (Legrand, spiralis (Lipina), and Endothyra of the group F, ? Mamet, and Mortelmans, 1966). The Tournaisian- prisca Eauzer-Chernoussova and Eeitlinger appear for Visean boundary is between Zones 9 and 10, and the top the first time. "Endothyra" (?) trachida Zeller is com­ of the Visean is the top of Zone 16s. Zones 17,18, and 19 mon. The zone also marks the appearance of Ca7-ci- are Namurian; only the lower part of the Namurian sphaera pachysphaerica (Pronina). This assemblage is was observed in the present study. found near the middle of the Mission Canyon Limestone Mamet and Skipp (1969) have already summarized in southeastern Idaho and Montana and near the middle the distribution of 107 taxa used in distinguishing of the Madison Limestone of central Wyoming. zones in the Mississippian of North America and have Zone 10 is marked by an outburst of Grloboendothyr