Rocks of the Red Eagle cyclothem are believed to have been deposited in warm, shallow marine water, sometimes clear, sometimes turbid, sometimes teeming with organisms, and sometimes almost lifeless. All animal fossils in the Red Eagle cyclothem are marine forms.
Following the principle of uniformitarianism, one may interpret ancient environments on the assumption that animals similar to living forms experienced analogous influences, preferences, and tolerances. Thus, certain fossils have come to be considered as reliable indicators of environment (environmental index fossils). They are admitted as evidence for reconstructing the environments in which the sediments were deposited. Conversely, the sediments may serve to indicate something of the conditions in which the fossils lived.
Commonly, the paleoecology of individual types of fossils is interpreted from their associations in a faunal assemblage. Certain members of the assemblage may be environmental indicators from which the living conditions of the entire group may be inferred. The assemblage, thus having acquired paleoecological significance, can then be used in paleosedimentary interpretations, even in the absence of some of the environmental index fossils which originally defined it.
Because the enclosing sediments may show that fossils were moved from their original positions and came to rest in a different environment, one should not depend on fossils alone for paleoecological interpretation. However, when fossils are absent, the paleoecology can be interpreted only from the physical characters of the rocks. Interpretations may be hindered by the fact that diagenesis can obscure or destroy the paleoecological record.
In the following discussion two aspects of paleoecology are treated separately. This first section summarizes the paleoecology of important groups and genera of invertebrates as generally interpreted and as supported or amended by this study. This section also deals with environmental index fossils and their significance. The second section presents the paleosedimentation (depositional environments) of the major lithologic units in the Red Eagle cyclothem, interpreted by using information from the first section and other relevant data.
Detailed discussions of ecologic factors that control and limit the activities of organisms appear in both volumes of the Treatise on Marine Ecology and Paleoecology (Hedgpeth, ed., 1957; Ladd, ed., 1957). Weller (1957, 1960) gave concise appraisals of ecologic factors as they apply in paleoecology. The interpretations which follow are based on such current knowledge of ecologic factors.
All three members of the Red Eagle Formation contain calcium carbonate of algal origin. It is recognizable as the Osagia (Johnson, 1946) coating on shell fragments in the GIenrock and especially Howe Limestones. Another type appears as long, roughly horizontal, ribbonlike or sheetlike crustose layers (Pl. 5), commonly called linear algae (Anchicodium?), that occur mainly in limestone of the Bennett Member. Intact specimens are presumably in situ. Some of the ribbonlike material is broken and randomly oriented (Pl. 5B). It may have come from encrusted upright-growing algal forms (see Harbaugh, 1959, p. 303-306).
It is axiomatic that algae thrive only at depths where light penetration is sufficient to support photosynthesis. Turbidity and turbulence control light penetration in sea water. The purity of the Bennett Limestone containing obvious algal deposits suggests that there was little muddy material in the water.
If it is assumed that the earth crust of the Midcontinent region has not "drifted" appreciably since Permian time, present-day observations support an additional assumption: in clear water, the base of the photic zone and the compensation depths--in Kansas latitudes at noon on a cloudless, calm June 21st during Wolfcampian time--could have been at least 200 feet below the surface. Elias (1937) postulated that limestone such as the Glenrock was deposited at depths less than 180 feet. The presence in the Glenrock Limestone of small amounts of algal material in situ indicates that Elias probably did not underestimate the depth of deposition of GIenrock-type limestone in the Kansas Lower Permian. Probably he overestimated it, because, as Ellison (1951) noted, about "95 percent of light available for photosynthesis has been absorbed in waters 50 meters in depth." In fact, more than 50 percent of the total incident light is transformed into heat and is extinguished in the top meter of pure water (Reid, 1961, p. 97). Certainly algal growth involves more than mere presence of light. Intensity and wave length of light are also significant if algae are to flourish.
Elias (1937, p. 410) stated that calcareous algae favor depths between 75 and 110 feet. Illing (1954) pointed out that in the Bahama Banks calcareous algae abound near the edge of the banks (depths of about 50 to 60 feet), where they contribute the major portion (40 percent) of calcium carbonate to accumulating sediments. Johnson (1954, p. 36) stated that the modern coralline algae grow best at depths less than 70 feet. Deeper than this (Johnson, 1954; Teichert, 1958) they diminish in size and abundance. Cloud and Barnes (1948) wrote that depths less than 15 fathoms (90 feet) are favorable to good development of algae. Williams and Barghoorn (1959) were convinced that control of calcium carbonate precipitation by plants is best at depths shallower than 60 feet. Algal biscuits in Florida Bay are found in waters 2 to 5 feet deep (Ginsburg and Lowenstam, 1958). Cryptozoon-type algal stromatolites (algal buns) are presently forming in intertidal depths at Shark Bay, Western Australia (Logan, 1961). Accordingly, it seems wholly justifiable, and rather conservative, to assume that the profuse oolitic (Osagia) carbonates in the Howe Limestone were probably deposited in water much less than 60 feet deep, because analogous pelletoid materials are presently accumulating in water less than 5 feet deep on the Bahama Banks (Imbrie, 1962, personal communication; Freeman, 1962).
The few algal-coated shell fragments within the Glenrock Limestone show no signs of abrasion or other suggestions of damage due to transportation. This indicates that although the fragments must have been turned over by gentle currents from time to time on the Glenrock lime oozes (in order for the algae to grow all around the nuclei), these materials are found essentially in place and demonstrate that light penetration was sufficient to support sparse benthonic algal life at the same depths wherein fusulinids lived. Hence, the question arises as to whether such light penetration was because of shallow depth of water in Glenrock time or merely because slightly deeper water was exceptionally clear (free of suspended detritus). The amount of insoluble clay residue in northern Howe limestone is greater than in the northern Glenrock, so there is the possibility that Howe waters were slightly more turbid than Glenrock waters.
Large parts of the calcareous matrices of the Red Eagle Limestone are aphanitic-microcrystalline. Johnson (1946) suggested that such very fine grained calcite is an accumulation of dustlike algal particles. In these matrices traces of algal threads of the sort described by Johnson (1946, p. 1107) are rarely observable, possibly because of effacement by recrystallization. Thus, it seems reasonable to believe that much of the structureless, aphanitic calcium carbonate in the Red Eagle Formation limestone (especially Bennett limestone facies) is of algal origin. Also, bacteria may have precipitated some of the particulate calcium carbonate by removing carbon dioxide from sea water (Field, 1932). Where consolidated aphanitic algal accumulations are associated with crustose fragments of linear algae (Pl. 5), it can be suggested that if the algal ribbons grew in the upright position they may have served as filter traps for the fine algal detritus. Moreover, as Harbaugh (1959, p. 306) suggested, mats of fallen algal ribbons may have been "sufficiently rigid to maintain open spaces" which also could have served as filter traps for fine sediment. This may have led to accumulation of shallow calcareous banks similar to those described from Florida Bay by Ginsburg and Lowenstam (1958).
Marine and Brackish-water Plants
Oogonia of charophytes are present only in the Johnson Formation of the Red Eagle cyclothem. Johnson (1946) has pointed out that although many living forms of charophytes live in fresh and brackish water, Paleozoic forms seem to have lived in shallow marine water. They appear to have thrived in clear, lime-rich water.
The oogonia of charophytes in calcareous mudstone of the Johnson Formation support the conclusion that these beds were deposited in shallow marine, limy water of less than normal salinity. Perhaps this is why fossils are so rare in the Johnson Formation. A tentative explanation of such abnormal conditions is given on page 48.
Spores are present in a number of shale units of the Red Eagle cyclothem, especially the Bennett black shale. They are of little use in marine environmental interpretations because they must have been blown or washed into the Red Eagle cyclothem sediments from terrestrial sources. However, the assemblage seems to indicate a cool climate (H. L. Cousminer, personal communication) on land surrounding the sea of earliest Bennett time.
Waxy plant residue is also present in the Bennett black shale. Presumably much of this unidentifiable material is, like the spores, of terrestrial origin. Its presence merely demonstrates that the Bennett black-mud environment preserved plant material.
Carbonized Terrestrial Plant Material
The only significant black carbonaceous plant remains occur in the uppermost shale of the Johnson Formation. Plant material is randomly distributed through the mudstone and shale. It must have been buried quickly under accumulating Johnson clastics to have avoided destruction by physical or organic agencies. Some is gymnospermous, but other fragments, which might be seaweed, appear grassy. The material is too badly altered for certain identification.
Larger foraminifers, of which the fusulinid Triticites is representative in the Red Eagle cyclothem, are thought to have lived in warm, shallow seas. Elias (1937, p. 418) suggested that fusulinids were benthonic organisms that lived in tropical waters shallower than 180 feet. Triticites is abundant in the Glenrock Limestone Member of the Red Eagle Formation and rare in the Bennett Member.
In the Glenrock Limestone, fusulinids are so abundant that they commonly constitute a major part of the rock. They are associated with numerous brachiopod fragments and traces of ostracodes, bryozoans, and smaller foraminifers in a nearly pure calcareous matrix. Unlike the broken associated organisms, the fusulinids are only slightly damaged. This is typical of fusulinids (Dunbar, 1957). Their shape, size, and cellular internal structure all tend to resist breakage, but their undamaged surfaces here are nonetheless remarkable, and suggest that they are found nearly in place. At some localities the long axes of the fusulinids show slight preference for orientation in the bedding plane direction, but otherwise they are oriented randomly. Orientation in the bedding plane is to be expected, because spindle-shaped objects would be unstable in any other position than on their "sides". Their random orientation in the Glenrock Limestone might be explained by a seafloor covering of viscous calcareous ooze, which would tend to hold fallen fusulinids in random position somewhat in the way that gelatin can support fragments of fruit.
Another noteworthy characteristic of the fusulinids in limestone of the GIenrock and Bennett Members is that they do not have algal calcium carbonate coatings (e.g., Osagia), even in the company of brachiopod and other fragments which do have such coverings. This suggests that the fusulinids were moving about on a substratum where algae were depositing calcium carbonate on and around broken shell detritus of several kinds. Perhaps the fusulinids were either too active to permit algae to accumulate on them, in the way (literally) that "rolling stones gather no moss," or their physiologic habits repelled algae. Perhaps, even after death, the chemical makeup of their shells was distasteful to algae.
There is no doubt that Red Eagle fusulinids preferred clear water. They are numerous only in limestone containing less than 15 percent of insoluble clay and silt detritus. Moreover, the pure calcium carbonate tests of fusulinids can be as much as 60 percent (by volume) of the rock. Thus, if a limestone containing 50 percent (by volume) of fusulinid tests yields, for example, 5 percent (by weight) of insoluble residue, the matrix would actually contain about 10 percent of insoluble residue. It is, of course, the matrix that reflects the degree of turbidity of the depositional waters. Glenrock matrices where fusulinids are abundant contain slightly more calcium carbonate than where fusulinids are sparse.
The association of fusulinids with algal carbonates also indicates warm clear water shallow enough to permit light penetration sufficient for algal photosynthesis. This evidence suggests that Elias (1937) was correct to the extent that he postulated fusulinids in Lower Permian rocks of Kansas (including the Red Eagle Formation) lived in water less than 180 feet deep. However, they might have lived at depths less than 30 feet (Imbrie and others, 1959, p. 78).
Normally, temperature is a major control of the distribution of foraminifers in open seas (Glaessner, 1955; Myers and Cole, 1957), but it does not dominantly influence zonation in shallow water (Myers and Cole, 1957, p. 1076). Hence, temperature being less important at such shallow depths, light (function of depth) should have been one of the principal controls of Red Eagle foraminiferal distribution, probably because of its control over the microscopic plants necessary in the foraminifers' diet.
During Glenrock time clear, marine, fusulinid-rich water of uniform depth and faunal content must have covered much of northeastern Kansas and southeastern Nebraska. That is, deposition of the Glenrock Limestone was uniform over broad areas of the Midcontinent region, far from shore or sources of detrital silicates.
In brief, the sedimentary relations of fusulinids in the Glenrock Limestone indicate that, as Dunbar (1957, p. 753) phrased it, "they lived and accumulated on a quiet sea floor free from active agitation by waves and free from bottom currents capable of transporting and size grading the empty shells." Dunbar made it clear that the normal habitat of the benthonic fusulinids is believed to have been in shallow epeiric seas.
Fusulinids in black tubes near the top of the Glenrock Limestone seem to have fallen into worm tubes or holes made by some other animals. The tube-makers must have burrowed downward from basal Bennett black mud into loosely consolidated Glenrock lime mud. The few loose fusulinids that lie atop the Glenrock Limestone (slightly impressed into it) and that are largely engulfed by black Bennett mud could have been killed by the first incursion of toxic Bennett muddy conditions.
If the sparse fusulinids which are present in some Bennett limestone beds are approximately in situ, they must have lived under conditions close to the tolerance limits of fusulinids. The implication of their smaller numbers, their faunal association, and their association with large volumes of algally deposited limestone would be that these fusulinids lived in very shallow water (?<50 feet: Laporte, 1962, Imbrie and others, 1959). A corollary to this would be that the algae possibly used large quantities of nutrients necessary to support fusulinid life. Moreover, the particulate algal calcium carbonate that was probably precipitating rapidly might have interfered with the food-intake mechanisms of the fusulinids, perhaps killing many before they could reproduce.
On the other hand, it is remotely possible that the fusulinids could have washed into the area of study from unknown sources, or that they might have been reworked from now-absent Glenrock deposits in central Kansas. However, these possibilities seem unlikely because the Bennett fusulinids show no damage or abrasion to suggest erosion or long transportation.
The very rare fusulinids in the top part of the Johnson Shale at the Highway 38 section are broken and abraded, suggesting damage during long transportation from an unknown source area. The single fusulinid shown by O'Connor and Jewett (1952, p. 335, pl. 10) is insufficient to permit explanations of its significance in the Howe environment.
Almost all smaller foraminifers of the Red Eagle cyclothem are arenaceous forms. They are common in the Red Eagle Limestone, rare in the Johnson Shale, and extremely rare in the Roca Shale. They are not as restricted in their lithologic associations as Triticites. Such foraminifers, because of their small size and fragility, are difficult to extract from sedimentary rocks. Hence, their record and sedimentary associations in these and other sediments are incompletely known, and any paleoecological interpretation based on them is tentative.
The tolerance of the smaller foraminifers for a variety of marine conditions is suggested by their occurrence in lithologies ranging from nearly pure limestone to moderately calcareous shale and mudstone. Although Tetrataxis and Ammodiscus are present in various Red Eagle cyclothem lithologies, they occur most commonly in the rocks containing less than 40 percent of calcium carbonate. Glyphostomella is found in lithologies containing about 75 percent of insoluble clastic residue. On the other hand, Ammovertella and Tolypammina seem to favor the calcareous environments represented by lithologies containing less than 10 percent of insoluble residue. Thus, their preference for clear water is suggested. Also, calcareous places of attachment were preferred by these genera. Ammovertella were found encrusted on fragments of Rhabdomeson? and Fenestrellina?. Tolypammina are rarely seen encrusted on ostracodes.
Lane (1958) and Hattin (1957) noted that certain specimens of Osagia contained traces of the arenaceous foraminifer Ammovertella, together with Nubecularia, which, as Johnson (1946, p. 1103) discovered, is the intimate associate of calcareous algal filaments in all Osagia. In this study, too, traces of Ammovertella were found in Osagia of the Howe Limestone, and on some linear algae (Anchicodium?) in the Bennett Member as well. However, the Ammovertella are so few that these coincidences of occurrence can not be said to indicate definite organic associations (e.g., commensal, symbiotic). That is, considering the variety of calcareous materials on which it encrusts, Ammovertella in the Red Eagle cyclothem simply seem to have preferred calcareous surroundings or places of fixation. If they had encrusted on a calcareous algal coating of Osagia, they would naturally have been covered by the next-deposited Osagia layer, giving the false impression that Ammovertella were functional interrelatives of algae and active contributors to Osagia.
Insoluble residues from limestone in all parts of the Red Eagle cyclothem commonly contain traces of "stuck together" quartz silt, most of which probably came directly from arenaceous foraminiferal tests similar to (or actually belonging to) Ammovertella and Tolypammina.
Few definite opinions about the paleoecology of the smaller foraminifers are forthcoming from the available evidence. Presence of these animals in a variety of lithologies suggests that they could tolerate a moderately wide range of environmental conditions and thus are of little use as environmental indicators in paleoecological interpretations. Information about their environmental preferences must be deduced from considerations of their role as part of the entire faunal assemblage and of the paleosedimentation of the Red Eagle and other cyclothems.
Johnson waters (see Table 7) seem to have been generally inhospitable to foraminifers. Only Ammovertella and Tolypammina were able to establish themselves during periods of clearer water in later Johnson time, represented by limestone layers in the upper part of the Johnson Shale. Large and small foraminifers thrived in the clear water of Glenrock time. Foraminifers did not live in the toxic water or on the black muddy sea bottom of early Bennett time. As deposition of the Bennett Member progressed and the environment became more favorable, smaller foraminifers and the other marine invertebrates abounded in the calcareous, sometimes turbid, waters represented by Bennett limestone and shale. The clear, shallow-water environment represented by the sparsely fossiliferous aphanitic Howe Limestone of southeastern Nebraska seems to have been favorable enough for a foraminifer population somewhat reduced in number of genera and individuals as compared with the Bennett fauna and the osagitic Howe fauna.
A variety of lithologies throughout the Red Eagle Formation contain bryozoans. They are especially common in the Bennett Member. Only a few traces of bryozoans are present in the uppermost parts of the Johnson and Roca Shales. Their association with a profusion of crinoids, brachiopods, foraminifers, and a variety of other marine organisms in the Red Eagle Limestone indicates that they thrived in normal marine water in the shallower reaches of the neritic range of environment, where the water was warm and life was abundant. Bryozoans in the Red Eagle Limestone, although broken, are little abraded, suggesting that they were not moved very far from their environment of origin.
Bryozoans are virtually absent from the Johnson and Roca Shales; thus, there is the question whether they were erased from the record during diagenesis or not deposited. The former possibility is rejected because a few calcareous marine fossils (some delicate) are present in the Johnson Formation, and there is no apparent reason why bryozoans, had they been present, should have been removed while the others remained. Thus, it seems probable that bryozoans were absent from the Johnson and Roca environments because of some unfavorable ecologic factor(s). Living bryozoans are known to abound from low-tide levels to depths greater than 600 feet, so that depth does not seem to have been an unfavorable factor. Another possibility is that bryozoans were absent from the mud-bottomed Johnson environments because substantial objects for attachment of their larvae (Duncan, 1957) were lacking.
Subnormal salinities, suggested by the presence of charophytes in the Johnson beds devoid of bryozoans, also may have prevented the establishment of bryozoans, probably during their larval stage. Osburn (1957, p. 1110) noted that, in general, salinities of less than 20 parts per thousand (normal open sea water averages about 36‰) are unfavorable to bryozoans. Thus, the absence of bryozoans from shale of the Johnson and Roca Formations lends support to the possibility that abnormally low salinity (brackish) conditions prevailed during their deposition.
Elias (1937) advanced the idea that bryozoans in these beds, and in adjacent cyclothems, lived in water between 75 and 160 feet deep. Stach (1936) noted that many bryozoans live at depths between 60 and 120 feet, where they are subject to some current and wave action. In view of the habits of living bryozoans, Elias' range of depth should not be construed as the depth limits outside of which bryozoans could not have lived during Early Permian time. The assumption should be that if waters had been deeper than 160 feet, bryozoans could have survived there. It also may be safely assumed that bryozoans could have become established in water shallower than 60 feet in protected places where they would not be destroyed by turbulence. Although there is no evidence of bottom relief sufficient to afford such protection, upright algal growths might have helped to provide it. If Elias' and Stach's figures are correct, it might be suggested that in the smooth-bottomed shallow sea indicated by the Red Eagle cyclothem, most turbulence (i.e., lowering of effective wave base) was shallower than 60 feet. That is, bryozoans favored bottoms below a normal wave base not deeper than 60 feet and possibly much shallower. Broken bryozoans in the Bennett calcareous shale suggest that turbulence during unusually severe storms might have shattered the bryozoans living below normal wave base, or fish such as sharks may have chewed them.
One specimen of Rhombopora? (possibly Rhabdomeson?) was seen encrusting part of a productid brachiopod spine. Duncan (1957, p. 789) stated that there are "examples of bryozoans attached to fossil shells that are highly suggestive of commensal or amensal relationships." Whether the bryozoan encrustation occurred during the life of the brachiopod or merely on a piece of spine detritus is uncertain.
The bryozoans in the Red Eagle Formation seem to have favored the clear, calcareous environments represented by limestone. However, they are found at random throughout a variety of fossiliferous calcareous mudstones, suggesting that they could tolerate a good deal of mud in water of approximately normal marine salinity. Their faunal and sedimentary associations demonstrate that they thrived below normal wave base in shallow water probably much less than 60 feet deep. The scarcity of bryozoans in any part of the Red Eagle sequence may be due to excessively shallow water or other unfavorable and physically severe conditions (see Duncan, 1957, p. 786). The euxinic environment of the Bennett black mud must have been very unfavorable to bryozoans. Temperature does not seem to have been a limiting influence on bryozoan growth within the Red Eagle cyclothem environments.
Like other calcareous invertebrate remains, brachiopods are most numerous in the Red Eagle Formation and rare in the Johnson and Roca Formations. There is no doubt that the articulate brachiopods flourished in the clear calcareous environments represented by Red Eagle limestone beds, but many genera also occur in a variety of muddy lithologies. Only the inarticulates Orbiculoidea and Lingula are present in the laminated Bennett black shale (conodonts and fish teeth are usually the only other fossils present). These delicate fossils are commonly found unabraded and almost unbroken or gently crushed by vertical pressure, so that their occurrence in situ in black shale is quite certain. It seems, therefore, that these animals could tolerate foul, euxinic, black muddy bottoms. Orbiculoidea is present also in calcareous muddy lithologies and even in limestone (especially the lower parts of Bennett limestone beds), indicating that it could tolerate environments ranging from the very toxic black mud milieu to clean, "healthful," limy bottoms.
The suggestion that Lingula was tolerant of the toxic Bennett black mud milieu is in keeping with known habits of living Lingula. As remarked by Shrock and Twenhofel (1953, p. 339), "Lingula does not seem to be affected by brackish water or by water so foul from decomposing organic matter that burrowing molluscs are unable to survive." Thus, Lingula seems to be, in present seas, much as it was during Red Eagle time. In 1902, Morse (see Cooper, 1957b) stated that Lingula has always dwelt in a shallow-water shore zone and therefore has not felt the effects of eustatic or epeirogenic changes. Consequently, it evolved little and has been essentially unchanged through geologic ages.
The Lingula-Orbiculoidea association in the black shale at the base of the Bennett Member is therefore thought to indicate that these beds were deposited in warm marine water almost certainly less than 60 and probably less than 10 feet deep. Moreover, the nature of the sediments as a whole indicates that the early Bennett waters were low in oxygen content and thereby rather toxic, so that most benthonic invertebrates could not live there. This further suggests that Lingula and Orbiculoidea had broad tolerance ranges for oxygen supply and salinity, but avoided depths greater than about 20 feet. It can be safely assumed that light, temperature, and supply of nutrients are factors involved in such depth sensitivity.
Articulate brachiopods, mostly calcareous, are very rare in the lower Johnson sediments, rare in upper Johnson and Roca sediments, and numerous in all members of the Red Eagle Limestone (especially the Bennett Shale). The organic and physical sedimentary associations of these brachiopods, and the nature of the brachiopods themselves, indicate that they lived in shallow, approximately normal marine water in both turbid and clear conditions on calcareous muddy bottoms. Many shells are broken or without their spines. This could be the result either of turbulent water or of the masticatory activities of mud-ingesting animals and nektonic and benthonic predators. The shell fragments are not worn or rounded.
Theories that the shape, ornamentation, and thickness of bivalve shells reflect the turbulent rigor of their living conditions are well known. The variety of brachiopod shell shapes, thicknesses, and sizes observable (broken and unbroken) in the Red Eagle sediments may indicate that they lived in water sometimes turbulent, sometimes quiet. Moreover, burrowing, fixed, and motile benthonic forms all seem to have thrived together in the GIenrock and especially Bennett environments.
Some indication of the temperatures of Bennett waters may be inferred from the presence of Neospirifer and Chonetes in calcareous shale. Lowenstam (1959) showed, from geochemical data, that the shells of some Early Permian Neospirifer probably formed in marine water at about 74°F.
Crurithyris, in a variety of lithologies and in all three formations of the Red Eagle cyclothem, seems to have been a brachiopod most tolerant of environmental changes.
The calcareous brachiopods in the upper part of the Johnson Shale are confined to southern Kansas, where the upper shale units are calcareous and contain a fauna somewhat similar to the Bennett of central and northern Kansas.
Small, smooth, spired and planispiral evolute gastropods are present, although scarce, in all units of the Red Eagle cyclothem. They occur in all lithologies of the cyclothem except the Bennett black shale. This suggests that although they could have lived in most sedimentary environments in water considerably less than 100 feet deep, they were among the many animals unable to tolerate the toxic early Bennett conditions. A slight preference for the more calcareous environments is suggested by relatively greater numbers of gastropods in limestone.
Many gastropods in osagite of the Howe Limestone are not coated by algal calcium carbonate. This may signify that these gastropods were moving about while the algae were growing, or that the geochemistry of their shells was distasteful to algae. Coated shells may have acquired their coverings after death.
The unique occurrence of a coiled nautiloid cephalopod at the top of the Howe Limestone near Allen, Kansas, is of little significance in paleoecological interpretation. Its stratigraphic association merely indicates the presence of coiled nautiloids in the very shallow Howe-type waters. That only one such nautiloid has been seen in the Red Eagle cyclothem suggests that it may be a freak occurrence, transported (alive or dead) far from its birthplace. Living nautiloids can float long distances before coming to final rest. Miller and Youngquist (1949, p. 4) seemed almost certain that most Permian nautiloids behaved similarly to presently living nautiloids. The unbroken condition of the Howe nautiloid suggests that it was not subjected to violent current action or other serious abuse after coming to rest on the Howe sea bottom. Its envelope of algal calcium carbonate indicates occasional gentle rolling so that algae were able to grow on all sides of the shell.
Modern Nautilus lives in depths from near low tide to almost 2,000 feet. Its ecology is poorly known.
The several straight nautiloids found only in the Howe Limestone at Coffman Ranch are not coated by algal carbonates, but they are embedded in an osagitic matrix. These nautiloids probably developed in a fairly open sea environment, but to attain their present position they must have been washed into the constricted Howe sea and stranded on the soft subtidal bottom.
PelecypodsMolds of Aviculopinna are extremely rare in the GIenrock and Howe Limestones. It is thought to have been a burrowing form (Elias, 1937, p. 419), but its rarity precludes definite paleoecological interpretation. The original shells buried in limestone could have been preserved because the lime was not stirred violently by currents before consolidation. On the other hand, diastems and common broken shell detritus in the Bennett Shale indicate that those Bennett sediments were disturbed by turbulent waters. It is not known whether Aviculopinna lived in Bennett mud. Perhaps some of the broken Bennett shell material is (comparatively frail) Aviculopinna. Allorisma is more robust than Aviculopinna and is very rarely found in the Bennett shale and in the Howe Limestone.
One explanation of the peculiar flattened clay-filled tubes in the GIenrock Limestone (Pl. 1B, 1C) is that they are worm burrows. Apparently worms burrowed into the GIenrock sediments from the overlying black Bennett mud. The tubes suggest that in earliest Bennett time the GIenrock had not fully consolidated, so that worms could forcefully advance through the soft sediments. However, some worms can bore through consolidated limy material by secreting acids. Thus, it is not known whether the tubes were made in the GIenrock sediments before or during appreciable consolidation. However, individual fusulinids, Orbiculoidea fragments, and Bennett mud trapped in the tubes suggest that the sediment was firm enough for the tubes to remain open. [Note: Ginsburg (1957, p. 85), in discussing worm tubes in Recent sediments, pointed out that filled and "open unlined burrows are very abundant in shallow-water carbonates."] Flattened parts of the tubes indicate that consolidation and compaction were completed after the time of burrowing. The tubes had to be open to allow the fragments of Orbiculoidea, fusulinids, and mud particles to fall from the Bennett mud above to the bottom of the tubes.
Other smaller and somewhat different worm tubes are present in upper Johnson calcareous mudstone and upper Roca limestone. Some might be tubes of animals similar to phoronids.
The assumption that the tubes were made by worms does not preclude the possibility of their manufacture by some other type of tube-making organism. It is difficult to imagine what sort of organism this could be, because no pelecypod, crustacean, echinoderm, or any other shelled burrower has been found at the end of any tube. Consequently, worms seem to be the best possibility, because their soft bodies could decay and leave no trace.
Ostracodes are common in the uppermost shale of the Johnson Formation and in the Red Eagle Formation, but they are rare in the Roca Formation. They occur in almost all calcareous rock types in the Red Eagle cyclothem but not in red or black shale.
Sediments enclosing the ostracodes and their numerous and varied faunal associates indicate that some kinds of ostracodes could survive in almost every calcareous marine environment within the Red Eagle cyclothem. As a group they seem to be independent of sedimentary facies. Apparently most of them thrived best in somewhat turbid carbonate-rich water of normal salinity. The toxic conditions indicated by the Bennett black shale and high salinities suggested by Roca red shale were probably inimical to most ostracode life.
The relatively greater number of smooth-shelled ostracodes (in both horizontal and vertical distribution), such as Bairdia and Cavellina, suggests that they were able to tolerate a broader variety of marine environments than the rarer ornamented forms, such as Amphissites.
It is remarkable that many ostracodes in the Red Eagle cyclothem are either intact or gently crushed flat by vertical pressure, especially where they accumulated along laminae of shale. In view of their molting habits, delicate shells, easy transport, and association with coarse detritus, it seems clear that these almost undamaged ostracodes were not transported far. Soft and muddy bottom sediments may account partly for their preservation. If some types of ostracodes died in their burrows, the bottom muds could have protected them from abrasion. Also, if eroded, the muddy bottom would cushion them against the adverse effects of tumbling by gentle currents. Many ostracodes present in the nonlaminated mudstone beds seem to have been quickly buried.
If ostracodes were ingested and subsequently evacuated by larger organisms it is likely that they were too small to suffer the same degree of damage or breakage by mastication as larger shells. This seems tenable because it is known that shells much larger than ostracodes can pass through the alimentary tracts of fish with little breakage and virtually no abrasion (Sogandares-Bernal, 1955, personal communication).
Within the Red Eagle Limestone formation, especially the limestone members, many ostracodes are randomly oriented. In Bennett shale units there is some preferential orientation of ostracodes parallel to bedding and along laminae, but orientations are random in mudstone. The shape and light weight of ostracode shells is such that they should tend to lie flat on the sea bottom. Even the gentlest of currents would aid such alignment. Perhaps the muddy bottom tended to support some ostracodes in random orientation exactly as they fell, without permitting realignment.
It is noteworthy that great numbers of exceedingly frail, smooth ostracode shells occur along laminae in uppermost Johnson gray shale and mudstone. In fact, these layers of ostracodes are planes of textural difference and, consequently, of weakness or parting, which are recognized as laminations. The frailty and lack of damage of the ostracodes indicate that they are probably in situ. Ostracodes are few and randomly oriented in the interlaminar mudstone. Perhaps these were burrowing forms.
Periodical mass mortality of ostracodes in late Johnson waters could have caused the rain of ostracodes which accumulated along the lamination planes. It is suggested that such mass mortality may have resulted from a decrease of salinity caused by sudden influx of fresh water bearing plant detritus. This combination of events is admittedly hypothetical, but sporadic fluctuations of regional climate offer a tentative explanation for the phenomena recorded in the uppermost Johnson shale. If low salinity had been the prevailing condition during late Johnson deposition, and if the water cleared and became more normally saline and calcareous during periods of less rainfall on land, marine ostracodes may have become abundant. A return to low salinity would attend increased rainfall and dilution by fresh water carrying plant detritus and mud. This could explain both the mass mortality of ostracodes and the traces of carbonaceous woody plant remains in mudstone and shale between ostracode-bearing laminae.
Salinity changes may not have affected the ostracodes directly but could have controlled the microorganisms upon which the ostracodes fed. A few genera, such as Bairdia, Bythocypris, and Cavellina, apparently were able to endure a sizable range of salinity conditions.
Except for the calcareous upper Johnson sediments at the Grand Summit section, columnal remains of crinoids within the Red Eagle cyclothem are present exclusively in the Red Eagle Limestone. Most crinoid columnals in the Red Eagle Limestone are disarticulated and dispersed but unabraded. This suggests a slight amount of transportation. The lack of abrasion may be due to their solid structure, as opposed to the soft Red Eagle bottoms on which they came to rest. Many columnals in shale are flattened, presumably during compaction of the sediment. No crinoid calices have been found in the Red Eagle cyclothem.
In the upper part of the Bennett at the Coffman Ranch section crinoid columnals are common, many still articulated. This suggests that they remained nearly in situ, where they accumulated to form a local crinoidal shell bank.
Laboratory analyses of the crinoidal limestone reveal a low percentage of insoluble clastics. This tends to confirm the judgment that crinoids lived in clear water. Preference of crinoids for clear calcareous environments is also shown by their rare to common occurrence in other Bennett limestone and their scarcity in the Bennett mudstone and shale. Such clear water also would have been ideal for the algae which are believed to have contributed much calcium carbonate to the limestone of the Red Eagle.
Echinoid spines are present in the Red Eagle Formation in the same sediments as crinoid stems, suggesting that echinoids favored nearly the same habitats as crinoids--warm, clear, calcareous, gently agitated waters on limy bottoms. Very few cidaroid interambulacral plates are present in the Bennett Member. Gentle currents could account for broken, disjointed, and dispersed but unabraded fragments of echinoids. Echinoid spines commonly accompany productid brachiopod spines.
Many Recent echinoids live in shallow clear water on either a sandy or limy bottom. Consequently, from the above interpretations it may be inferred that the habitats preferred by echinoids have not changed appreciably since Early Permian time.
Conodonts and Fish Remains
A somewhat arbitrary distinction is drawn between conodonts and fish teeth. In addition to color and structural differences, the mode of occurrence of conodonts is somewhat different from that of fish teeth. Conodonts (e.g., Streptognathodus, Hindeodella, Ozarkodina) are common in the black shale of the basal Bennett Member and rare in other Bennett shale. Fish teeth (e.g., Idiacanthus, Palaeoniscus, Distacodus) are rare in upper Johnson gray shale, common in all Bennett shale, and extremely rare in the Howe Limestone, Glenrock Limestone, and lower Roca Shale. Lower Johnson Shale and upper Roca Shale lack conodonts and fish teeth.
Conodonts are thought to be parts of the dental structures of vagrant nektonic animals similar in habit to, if not truly, fishes (Schmidt, 1950, cited in Ellison, 1957). Such habit explains the fact that they occur in black shale (barren of other fossils) indicative of toxic ecologic conditions, as well as in fossiliferous shale and limestone which record more favorable environments. If nektonic, these unknown animals could have lived in near-surface waters above bottom environments too poisonous to support aerobic organisms. When they perished, their remains could have fallen on any bottom, whatever its characteristics. An alternative possibility is that anaerobic environments provided the normal conditions for the animals from which conodonts are derived. Furthermore, the reducing conditions that account for black shale probably favored preservation of conodonts.
The absence of conodonts or fish teeth from most Johnson and Roca sediments is difficult to explain, because it is not unlikely that conodont-bearers and tooth-bearers could have lived in near-surface waters, if not close to the muddy Johnson and Roca bottoms. If conodont-bearers dwelt in or above the wide range of bottom environments recorded by Red Eagle sediments, it would seem odd that they should have been unable to tolerate the Johnson and Roca waters wherein a few ostracodes lived. Of course, they could have been removed from the sediments during diagenesis, but such diagenetic selectivity (removal of conodonts but not ostracodes) seems unlikely.
In the black shale, conodonts and fish remains are associated with Orbiculoidea, Lingula, macerated plant remains, and spores. This type of association was normal for conodonts even in the Devonian (Ellison, 1957, P. 993).
Cyclothemic Nature of the Faunal Assemblages
Elias (1937) asserted that depth of deposition seems to have been the main factor that controlled the sedimentation and fauna of the rock sequence of the Red Eagle and other cyclothems. He postulated that certain faunal assemblages lived in certain phases of the repetitious marine sedimentary environments which resulted from rhythmic changes of water depth early in Permian time. Consolidated faunal and sedimentary repetitions in orderly succession are recognized as cyclothems. Elias noted that each of these cycles has a progressive and a regressive half-cycle, which presumably reflect deepening and shallowing of the seas, respectively. In the regressive part of a theoretically complete cycle, the sequence is exactly opposite to that of accumulation during the progressive part. Elias (1937, p. 411) recognized seven faunal-lithological "phases" in each half of a complete or ideal, cycle.
Table 4 is a modification of Elias' list of idealized cyclothemic phases, with his interpretation of their depths of deposition. Hattin (1957) suggested the addition of phase 0 at each end of the list to accommodate rare terrestrial channel sandstones not provided for by phases 1 through 7.
Table 4.--Idealized Lower Permian cycle of deposition in north-central Kansas (modified from Elias, 1937, and Hattin, 1957).
on paleontologic evidence
Elias (1937, p. 411) was careful to state that "no single cycle . . . shows all phases of the ideal cycle, but the missed phases of one cycle appear in proper position in neighboring cycles above and below." Several of these basic faunal assemblages (phases) are present in rocks of the Red Eagle cyclothem. Table 5 shows sedimentary units of the Red Eagle cyclothem recognized in this study and the phases they represent (following Elias). The progressive (transgressive) and regressive phases thus determined within the Bennett Member are noteworthy.
Table 5.--Units of the Red Eagle cyclothem defined in terms of Elias (1937).
|Unit of the Red Eagle cyclothem||Elias's depth
|medial red shale||0||Red shale||1|
|lower greenish shale||0-30||Green shale||2r|
|Red Eagle Limestone|
|Howe Limestone Member||60-90||Molluscan phase||4r|
|Bennett Shale Member|
|upper gray shale||90-110||Mixed phase||5r|
|medial limestone||110-160||Brachiopod phase||6|
|lower gray shale||90-110||Mixed phase||5p|
|basal black shale||30-60||Lingula phase||3p|
|Glenrock Limestone Member||160-180||Fusulinid phase||7|
|upper greenish shale||0-30||Green shale||2p|
|medial red shale||0||Red shale||1|
A fusulinid facies is characteristic of, and dominates, the upper part of the Glenrock Limestone. This corresponds to Elias' phase 7 (fusulinid phase), which he described as indicating depositional depths between 160 and 180 feet. A few brachiopods, bryozoans, foraminifers, calcareous algae, and crinoids accompany the fusulinids.
Lingula, with Orbiculoidea and conodonts, are the dominant fauna of the black and dark-gray shale of the lower Bennett Member. Elias' phase 3 is the lingula phase, which he estimated as indicating depths of deposition probably less than 60 feet. However, Elias noted sandy lithologies as typical bearers of Lingula. In the Red Eagle cyclothem Lingula occurs mainly in black shale.
A fauna rich in productaceans and spiriferids dominates the gray shale of the lower part of the Bennett Member immediately above the black-shale fauna. Bryozoans, with ostracodes, foraminifers, gastropods, crinoids, and holothurians, are lesser components of the fauna. This assemblage is recognized as the mixed phase (phase 5) of Elias, which he stated was deposited at depths between 90 and 110 feet. Bennett limestone exhibits a sparse brachiopod fauna (Elias' phase 6), including some horn corals.
A mixed faunal assemblage (Elias' phase 5) of brachiopods, bryozoans, foraminifers, gastropods, crinoids, mollusks, and ostracodes is repeated in the upper part of the Bennett Member. It is succeeded by the very abundant, calcareous, algal osagite of the Howe Member. The Howe Limestone appears to be approximately equivalent to Elias' molluscan phase (phase 4), which he postulated as accumulating at depths between 60 and 90 feet.
Although it is agreed that regular or irregular changes of water depth must have been of prime importance in molding the Red Eagle cyclothem biofacies and lithofacies, this study recognizes that regional climate, tectonism, supply rate of muddy clastics, and movement and chemistry of the waters must all have been interrelated and must have modified and sometimes subordinated the depth effects on Red Eagle cyclothem sedimentation. Moreover, the effects of interference of eustatic and local tectonic influences on depth, facies-genesis concepts such as those of Imbrie and others (1959), and other factors (see Weller, 1957) must be considered when interpreting Red Eagle cyclothem paleoenvironments. In view of expanded knowledge of modern environments, some revisions of Elias' depths of deposition seem necessary. To explain the ecologic conditions suggested by the Red Eagle cyclothem, water depth no greater than 60 feet need be postulated.
Kansas Geological Survey, Geology
Placed on web Jan. 4, 2007; originally published Dec. 1963.
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