in the dolomitic upper Fort Riley to Nolans Formations in northern Kansas and Nebraska. These rocks contain dissolution molds of evaporite crystals and ...
OXYGEN-CARBON ISOTOPE STRATIGRAPHY OF UPPER CARBONIFEROUS TO LOWER PERMIAN MARINE DEPOSITS IN MIDCONTINENT U.S.A. (KANSAS AND NE OKLAHOMA): IMPLICATIONS FOR SEA WATER CHEMISTRY AND DEPOSITIONAL CYCLICITY S.J. Mazzullo, 2Darwin R. Boardman, 3Ethan L. Grossman, and 4Kimberly Dimmick-Wells 1 Department of Geology, Wichita State University, Wichita, Kansas 67260 2 School of Geology, Oklahoma State University, Stillwater, Oklahoma 74078 3 Department of Geology and Geophysics, Texas A&M University, College Station, Texas 77843 4 formerly Department of Geology, Wichita State University, Wichita, Kansas 67260; now Woolsey Operating Co. LLC, Wichita, Kansas 67202 1
ABSTRACT: Late Pennsylvanian (upper Gzhelian = Virgilian) to early Permian (lower Artinskian = upper Wolfcampian) sea water chemistry and depositional cyclicity are evaluated based on oxygen and carbon isotopic compositions of unaltered shells of the brachiopod Composita collected from shallow-water deposits in the Council Grove and Chase Groups in Kansas and Oklahoma. Mean MgCO3 content in these samples is 0.2 ±0.2 mole%, and mean δ18OPDB and δ13CPDB values are -2.1 ±0.6‰ and 4.0 ±0.8‰, respectively. There is no significant difference in mean percentage MgCO3 or isotopic compositions between primary prismatic and secondary fibrous shell layers. δ18O trends do not appear to coincide with inferred sea water temperature changes attending deposition of stratigraphic sequences as has been postulated for older midcontinent Pennsylvanian cyclic deposits. Rather, the data seemingly reflect variations in sea water δ18O values coincident with ice-volume fluctuations during the time period examined. This contention is in accordance with inferred glacio-eustatic forcing of depositional cyclicity in the section. Estimated amplitudes of sea-level fluctuations increase from the upper Gzhelian into the lower Artinskian from 30-100 m to 110-150 m, which concurs with maximum Gondwanan glaciation during the early Permian. Although there is not a significant long-term trend in mean δ13C values, there is an upward trend to less negative δ18O values that is interpreted as a signal of long-term increase in midcontinent aridity and salinity.
INTRODUCTION Studies of the stable oxygen and carbon isotopic compositions of biotic and abiotic components in limestones have furthered our understanding of changes in sea water isotopic composition and temperature, global carbon budgets, history of glaciation, and deposition of cyclic sequences (e.g., Lowenstam 1961; Galimov et al. 1975; Veizer and Hoefs 1976; Veizer et al. 1980; Popp et al. 1986a; Beauchamp et al. 1987; Bruckschen et al. 1999; Mii et al. 1999). Such geochemical data also provide critical baselines against which isotopic compositions of cements and dolomite in ancient carbonate rocks are compared and interpreted (e.g., Given and Lohmann 1985; Lohmann and Walker 1989; Carpenter et al. 1991). The late Paleozoic is a focus of such studies because it was a critical period in Earth history that witnessed dramatic environmental changes coincident with Gondwanan glaciations and the transition from ice-house to greenhouse climatic modes (Veevers 1994; Veevers et al. 1994). Marine oxygen and carbon isotope records have been developed for the late Paleozoic from several areas in the world (e.g., Compston 1960; Veizer and Hoefs 1976; Popp et al. 1986a; Bruckschen et al. 1999), including a relatively detailed record for the Carboniferous of North America (Mii et al. 1999; Grossman et al. 2001a, b). Available isotope data from upper Paleozoic rocks in North America are based largely on either whole brachiopod shells or rock matrix (Brand 1982, 1987; Morrison et al. 1985; Wiggins 1986; Magaritz and Holser 1990), which generally are considered equivocal because of likely diagenetic effects. Unaltered brachiopod shells and marine cements in limestones are believed to provide more reliable isotopic data (Given and Lohmann 1985; Popp et al. 1986b; Carbonates and Evaporites, v. 22, no. 1, 2007, p. 55-72.
Lohmann and Walker 1989; Grossman 1994; Grossman et al. 1996). Limited marine cement data are available for the upper Paleozoic in North America (e.g., Davies and Krouse 1975; Davies 1997; Given and Lohmann 1985, 1986; Beauchamp et al. 1987; Graber 1989; Mruk 1989; Dickson et al. 1991; Mazzullo 1999b), but the bulk of available data from rocks of this age are from well preserved brachiopod shells (Popp et al. 1986; Veizer et al. 1986; Adlis et al. 1988; Grossman 1994; Grossman et al. 1991, 1993, 2001a and b; Mii et al. 1999). Whereas Carboniferous rocks in North America have been fairly well studied, there is a critical gap in brachiopod data from younger Paleozoic rocks, particularly from upper Gzhelian to Artinskian strata. This gap limits attempts at paleoclimatic modeling, comparative sedimentologic, diagenetic and biotic studies, and other reconstructions. This paper presents oxygen and carbon isotope data from unaltered brachiopod shells in upper Gzhelian to lower Artinskian (upper Virgilian to upper Wolfcampian), cyclic shallow-marine strata of the Council Grove and Chase Groups in central to southern Kansas and northeastern Oklahoma. These data extend the brachiopod isotope chemostratigraphy of Adlis et al. (1988), Grossman et al. (1991, 1993), and Mii et al. (1999) into the lower Permian, and allow direct comparison of isotope data from a similar sample base. Based on these data, late Paleozoic ocean chemistry and temperature, history of glaciation, and depositional cyclicity of these rocks are evaluated and discussed. STUDY AREA AND STRATIGRAPHY The Council Grove and Chase Groups are exposed
IMPLICATIONS FOR SEA WATER CHEMISTRY AND DEPOSITIONAL CYCLICITY Group are correlated to equivalent strata in Nebraska and Texas (Boardman et al. 1995; Mazzullo 1998, 1999a), and stratigraphic cyclicity is believed to have been forced by glacio-eustasy driven by Gondwanan glaciation.
from northeastern Oklahoma, through Kansas, and into southeastern Nebraska (Fig. 1). Total average thickness of both units is about 200 m, and they comprise cyclic, terrestrial siliciclastics and shallow-marine carbonates and shales that were deposited on ramps that dipped gently to the south and west (Boardman et al. 1995; Mazzullo 1998, 1999a). Deposition was in a shallow intracratonic basin located in a tropical, low-latitude setting that was 0-7o north of the paleoequator (Scotese and McKerrow 1990; Golonka et al. 1994). Stratigraphy and biostratigraphic assignments based on conodonts are shown in Figure 2. The Foraker Limestone and Johnson Shale in the lower part of the Council Grove Group are assigned to the upper Gzhelian (Virgilian) by Boardman et al. (1995), and therefore, are younger than Virgilian strata from which brachiopods were earlier analyzed by Adlis et al. (1988) and Grossman et al. (1991, 1993).
FOSSIL DATA BASE AND PALEOENVIRONMENTS The brachiopod shells on which this study is based were collected from calcareous shale and/or shaly limestone beds within only the early TSTs and late HSTs of the high-frequency cycles in the section (Fig. 2). Because deposition was on a very low-gradient ramp, these systems tracts and rocks represent shallow-marine deposits (i.e., above wave base) that we believe are of similar paleowater depth. Evidence for the recognition of inferred paleoenvironments includes: (i) position within the overall sequence-stratigraphic framework; (ii) lithology and biotic content, including superposition of different biota such as molluscs, fusulinids, ammonites, and conodonts; and (iii) vertical succession of sedimentary and biogenic structures (Boardman et al. 1995; Mazzullo 1998, 1999a). Specimens purposely were not collected from immediately beneath depositional-sequence or other cycle boundaries. Stratigraphic units shown in Figure 2 as not providing any specimens are those in which Composita either is not present in the study area, or in which the genus is present in only deeper-water deposits wherein shells are pervasively silicified. Samples were not collected from deeper-water deposits in the section. Hence, the present study is restricted to specimens from only shallow-water deposits, and all such deposits that contain Composita in the study area
The fundamental units in the section are relatively highfrequency cycles that generally comprise two marine carbonates, each with component transgressive and highstand systems tracts (TST and HST, respectively), separated by fossiliferous, nearshore-marine shale (Fig. 2). The shales represent relative lowstands that did not involve subaerial exposure. Such cycles constitute the typical “cyclothems” of midcontinent terminology. When such cycles are overlain and underlain by terrestrial siliciclastics, including palosols, they comprise mid-frequency cycles that are components of even lower-frequency cycles (Mazzullo 1998, 1999a). In the Chase Group, the midfrequency cycles are interpreted as stacked, composite depositional sequences, the deepest-water deposits of which are within the Florence Formation. In contrast, the relatively high-frequency cycles recognized in the Council Grove Group (and part of the underlying Admire Group) are interpreted as a single lower-frequency depositional sequence within which the Red Eagle Formation represents the deepest-water deposits (Boardman et al. 1995: Fig. 2). A slightly different perspective on cyclothem and sequence development in the lower part of the Council Grove Group, and also the subjacent Admire and Wabaunsee Groups, is given by Olszewski and Patzkowsky (2003). TST deposits identified in the present study are deepeningupward marine facies, and locally tidal flat facies. HST deposits shallow upward and are mainly represented by carbonate sands, and locally, also tidal flat facies. Maximum-flood deposits in the high-frequency cycles within the lower to middle Council Grove Group are mainly condensed sections represented by black, phosphatic “core shales” typical of Pennsylvanian cyclothems (e.g., Heckel 1994). Maximum-flooding deposits in the upper Council Grove and Chase Groups instead are mainly non-phosphatic and locally slightly glauconitic, fossiliferous and calcareous shales. These differences reflect overall shallowing from the Virgilian into the Wolfcampian (e.g., Rascoe and Adler 1983). The cycles in the Council Grove Group and Chase
Figure 1. Location of study area and of brachiopod collection sites. 56
MAZZULLO, BOARDMAN, GROSSMAN, AND DIMMICK-WELLS
Figure. 2. Stratigraphy, inferred depositional environments, and cycle hierarchy in the Chase and Council Grove Groups and units from which brachiopods were collected. Biota associated with Composita in the sampled sections include crinoids, bryozoans, and other brachiopods, which presumably instead suggest deposition in near-normal salinity environments (Thayer 1981).
were sampled extensively. In contrast, Adlis et al. (1988) and Grossman et al. (1991, 1993) examined the isotope stratigraphy of brachiopod shells collected within shallow to progressively deeper-water (maximum transgressive) profiles in older Missourian to Virgilian cyclothems to assess relationships among isotopic composition and temporal changes in paleowater depth.
METHODS The spiriferid brachiopod Composita subtilita (Grinnell and Andrews 1964) was specifically chosen for isotopic analysis because it is fairly common in the Council Grove and Chase Groups (Fig. 2) and it has a relatively thick, dense shell that should be relatively resistant to significant diagenetic alteration (Compston 1960). Furthermore, isotope data from these specimens can be compared directly to data from samples of Composita subtilita in older Pennsylvanian strata (Grossman et al. 1991, 1993; Mii et al. 1999; Grossman et al.2001a, b). Although other brachiopod genera commonly co-exist in the sampled sections, they were not collected for
Evaporitic paleoenvironments in the study area are inferred in only the upper part of the Chase Group, specifically in the dolomitic upper Fort Riley to Nolans Formations in northern Kansas and Nebraska. These rocks contain dissolution molds of evaporite crystals and nodules, and Composita is very rare to generally absent (Mazzullo et al. 1997). Samples were collected from those formations and all other units only in outcrops in central to southern Kansas and northeastern Oklahoma (Fig. 1), where the rocks do not contain evidence of above-normal salinity. 57
IMPLICATIONS FOR SEA WATER CHEMISTRY AND DEPOSITIONAL CYCLICITY analysis either because their shells are thin and were always found to be diagenetically altered (e.g., Chonetes, Derbyia, and Juresania), or because the shells are nearly always pervasively silicified (e.g., Reticulatia). Only specimens of Composita that had weathered cleanly out of the outcrops, and which were not obviously peripherally micritized or silicified, were collected. Approximately 800 specimens were collected following these criteria.
specimens. Textural alteration and variations in minor and trace-element compositions (e.g., Mg, Mn, Fe, Na, and S) commonly are employed to assess the extent of diagenetic alteration in fossil brachiopod shells (e.g., Veizer et al. 1980; Popp et al. 1986a, b; Rush and Chafetz 1990; Grossman et al. 1996). We compared the degree of micro-architectural preservation, luminescence characteristics (as a proxy for relative contents of Mn and Fe), and Mg content to evaluate the extent of shell alteration.
In the laboratory, specimens were cleaned with 1% dilute hydrochloric acid, rinsed in distilled water, and then sliced longitudinally with a water-based diamond saw. After re-rinsing with distilled water, both halves of the shells were stained with Alizarin red-S, and those found to be partially silicified or dolomitized were discarded (N = 630). All of the specimens from the Americus and upper Hughes Creek Members (Foraker Fm.), Morrill Member (Beattie Fm.), Middleburg Member (Bader Fm.), Funston Formation, Schroyer Member (Wreford Fm.), lower and middle part of the Florence and the lower part of the Fort Riley Formations (Fig. 2) were discarded. Although many additional samples subsequently were collected from these units, all of them also proved to be unusable. Remaining specimens (N = 170), all of which were entirely calcite, were examined with a Nuclide Luminoscope at 80-100 millitorrs and 14-18 kv (~0.7 ma) accelerating voltage, and a dental drill was used to recover micro-samples for comparative geochemical analysis of both luminescent and nonluminescent shell material. Samples were analyzed for their stable oxygen and carbon isotopic compositions (Tables 1 and 2) on Finnigan MAT 251 isotope-ratio mass spectrometers at Texas A&M University and the University of Michigan-Ann Arbor following standard analytical procedures. Precision is better than 0.1‰ for both δ18O and δ13C, values of which are presented in delta notation relative to the VPDB standard. Twenty of the samples analyzed were duplicates sent to each lab for evaluation of inter-lab variation in compositional results, which proved to be less than 0.08‰ for δ18O and 0.03‰ for δ13C. Sub-sets of all of the samples were analyzed for Mg contents by Xray diffraction using a Philips XRG 3100 at ¼o 2θ /minute, 40 kv, and 10 milliamps. Mole % MgCO3 (Tables 1 and 2) was determined by the peak shift method in reference to data in Mackenzie et al. (1983), which are correlated to mole % MgCO3 content based on atomic absorption spectrophotometry. Mg compositions determined by these two methods vary by less than 10%.
Normal light and cathodoluminescence petrography indicated that both the fibrous and preserved non-silicified prismatic layers in 39 of the 170 analyzed Composita shells are recrystallized and either luminescent (indicating relatively high Mn content) or nonluminescent (NL)(Table 2). These 39 samples are considered to be diagenetically altered. In contrast, both layers in the remaining 131 shells (Table 1) are NL and unrecrystallized, and have well preserved micro-architectural detail; even the prismatic layers in these samples were not silicified at the micro-scale. These 131 samples are considered to be diagenetically unaltered. In contrast, micritic sediment and/or calcite cements in the shells of all specimens are luminescent. According to Rush and Chafetz (1990) and others, although the apparently NL unaltered shells appear to be well preserved texturally, they nevertheless can be geochemically altered as well. Accordingly, micro-samples were collected for geochemical analyses from mainly the fibrous layers in recrystallized specimens, and from both layers in unrecrystallized specimens. Collection of these samples was restricted to approximately the same location on interior portions of the pedicle valves of shells to avoid possible effects of intra-specimen compositional variability (e.g., Popp 1986; Mii and Grossman 1994; Grossman et al. 1991, 1993, 1996). Mg Contents Analogy to modern brachiopods suggests that the fossil shells originally contained minor amounts of Mg (Lowenstam 1961). According to several workers, therefore, post-mortem Mg enrichment therefore indicates geochemical alteration (e.g., Al-Aasm and Veizer 1982; Grossman et al. 1996). Mean MgCO3 content in the 39 altered shells (Table 2) is 1.8 ±1.4 mole %. Specifically, mean MgCO3 content in the altered luminescent shells is 1.1 ±1.1 mole % (N = 22), and in the NL altered shells it is 2.7 ±1.2 mole % (N = 17). In contrast, mean MgCO3 content in the unaltered Composita shells is 0.23 ±0.21 mole % (range 0-1 mole %: Table 1), which is considerably less than in the altered samples. There is no difference within all sample groups in Mg content between fibrous and prismatic layers in individual samples (Table 1). Grossman et al. (1996) likewise reported low Mg contents (0.210.92 mole % MgCO3) in unaltered Composita from Upper Pennsylvanian rocks in Kansas, Missouri, Texas, and New Mexico. In our data set the MgCO3 values are interpreted
RESULTS Shell Microstructure and Preservation Shells of Composita subtilita are characterized by a relatively thick fibrous (secondary) inner layer, and a thinner prismatic (primary) outer layer that commonly is partly eroded (Grossman et al. 1996). Prismatic layers commonly were found to be partly silicified in many 58
MAZZULLO, BOARDMAN, GROSSMAN, AND DIMMICK-WELLS Table 1a. Geochemistry of nonluminescent and unrecrystallized, inferred unaltered Composita. (N = 131). Sample numbers with one asterisk indicate analysis of prismatic shell layers, and those with two asterisks indicate separate analyses of both prismatic (P) and fibrous (F) layers; sample numbers without asterisks indicate analysis of only fibrous layers.
59
IMPLICATIONS FOR SEA WATER CHEMISTRY AND DEPOSITIONAL CYCLICITY Table 1b. Geochemistry of nonluminescent and unrecrystallized, inferred unaltered Composita. (N = 131). Sample numbers with one asterisk indicate analysis of prismatic shell layers, and those with two asterisks indicate separate analyses of both prismatic (P) and fibrous (F) layers; sample numbers without asterisks indicate analysis of only fibrous layers.
60
MAZZULLO, BOARDMAN, GROSSMAN, AND DIMMICK-WELLS Table 1c. Geochemistry of nonluminescent and unrecrystallized, inferred unaltered Composita. (N = 131). Sample numbers with one asterisk indicate analysis of prismatic shell layers, and those with two asterisks indicate separate analyses of both prismatic (P) and fibrous (F) layers; sample numbers without asterisks indicate analysis of only fibrous layers.
61
IMPLICATIONS FOR SEA WATER CHEMISTRY AND DEPOSITIONAL CYCLICITY Table 1d. Geochemistry of nonluminescent and unrecrystallized, inferred unaltered Composita. (N = 131). Sample numbers with one asterisk indicate analysis of prismatic shell layers, and those with two asterisks indicate separate analyses of both prismatic (P) and fibrous (F) layers; sample numbers without asterisks indicate analysis of only fibrous layers.
62
MAZZULLO, BOARDMAN, GROSSMAN, AND DIMMICK-WELLS Table 1e. Geochemistry of nonluminescent and unrecrystallized, inferred unaltered Composita. (N = 131). Sample numbers with one asterisk indicate analysis of prismatic shell layers, and those with two asterisks indicate separate analyses of both prismatic (P) and fibrous (F) layers; sample numbers without asterisks indicate analysis of only fibrous layers.
little to no metabolic fractionation in their thick fibrous shell layers (Lowenstam 1961; Lepzelter et al. 1983; Carpenter and Lohmann 1995). Although isotopic disequilibrium is indicated in the prismatic layers of some brachiopods (Carpenter et al. 1991; Carpenter and Lohmann 1995), our data argue against this effect in the samples analyzed (Fig. 3C). Hence, brachiopod δ18O values are believed to be dependent mainly on sea water δ18O and temperature. The δ18O variability within each sampled formation in the Chase and Council Grove Groups is small (mean δ = 0.6‰: Table 1) and may reflect seasonal temperature variability during shell growth and/or spatial and temporal variations in sea water δ18O. Both factors are environmental parameters that are affected by depth, salinity and rates of evaporation, and water circulation. We attempted to minimize the possible effects of seasonal growth variability by analyzing samples from similar locations on each shell (e.g., Grossman et al. 1993, 1996). By collecting samples from similar paleoenvironments we likewise attempted to minimize possible effects induced by micro-habitat differences and spatial variations in temperature and sea water δ18O, and also possible effects of relative temperature variations caused by significant differences in paleowater depth. Although such effects are impossible to totally eliminate, the remaining factors – sea water δ18O, temperature, and salinity – are considered to be most relevant in this study.
to substantiate that the recrystallized NL Composita shells are geochemically altered, whereas the unrecrystallized NL shells are unaltered. Oxygen and Carbon Isotopic Compositions Despite evidence of geochemical alteration, the field of MgCO3 content and δ18O values in the altered Composita overlaps that of unaltered samples, with only three instances where NL altered Composita samples are significantly more 18O-depleted than the remainder of the data set (Fig. 3A). These three samples likely were contaminated with luminescent micrite matrix and meteoric calcite cement. Mean δ18O and δ13C values of the luminescent altered samples (N = 22) are -2.5 ±0.8‰ and 2.5 ±1.5‰, whereas those of the NL altered samples (N = 17) are -2.6 ±1.8‰ and 3.1 ±2.3‰, respectively (Table 2). Although there is overlap in the isotopic compositional fields of the altered and unaltered samples (Fig. 3B), the mean δ18O and δ13C values of altered shells (-2.6 ±1.1‰ and 2.8 ±2.0‰: Table 2) are slightly lower than those of unaltered shells (-2.1 ±0.6‰ and 4.0 ±0.8‰: Table 1). Likewise, the range of δ18O and δ13C values of unaltered shells is less than that of altered shells (Table 1). Decreases in both δ18O and δ13C attending diagenesis in Composita shells has also been reported by Grossman et al. (1991, 1993).
Sea water temperatures possibly were relatively constant in such shallow, low-latitude seas as in the study area during glacial-interglacial transitions (CLIMAP 1981). However, it may be more likely that the stratigraphic trends of δ18O (and δ13C) in unaltered Composita (Fig. 4) reflect bottomwater temperature changes attending glacio-eustatic fluctutations (e.g., Crowley and Baum 1991; Guilderson et al. 1994). If so, then mean δ18O values should increase during low-frequency cyclic transgressions (colder), and then decrease during ensuing regressions (warmer -- see “expected” curve in Fig. 4: Adlis et al. 1988; Grossman et al. 1991, 1993). Although the absence of Composita and/or lack of well preserved samples in some parts of the section limits our interpretations, the available data seem to indicate
Significant differences in the δ18O and δ13C values of cooccurring fibrous and prismatic layers (0.21-0.37‰ and 0.39-0.56‰, respectively) is evident in only two of the 11 samples of unaltered Composita shells (Table 1). These differences are minimal in the remaining samples (Fig. 3C), which supports the validity of the isotope data from either shell layer in samples of unaltered Composita (Table 1). INTERPRETATIONS Oxygen Isotope Stratigraphy The δ18O value of Composita shells is presumed to reflect approximate equilibrium with ambient sea water because of 63
IMPLICATIONS FOR SEA WATER CHEMISTRY AND DEPOSITIONAL CYCLICITY Table 2a. Geochemistry of recrystallized, non-luminescent (NL) and luminescent (CL) Composita samples (N=39).
64
MAZZULLO, BOARDMAN, GROSSMAN, AND DIMMICK-WELLS Table 2b. Geochemistry of recrystallized, non-luminescent (NL) and luminescent (CL) Composita samples (N=39).
measured brachiopod δ18O values. Somewhat evaporative environments were present, for example, in the uppermost Fort Riley Formation, Luta Member, and Herington Member in the Chase Group. Mean brachiopod δ18O values in these units are mostly enriched relative to other units in the Chase Group, with the Herington Member having the highest mean value (-0.63‰; Table 1 and Fig. 4). In fact, there is a vague trend toward oxygen isotopic enrichment upward within the Chase Group that may reflect increasing aridity during this time (e.g., Railsback et al. 1989). However, mean δ18O values in the Fort Riley and Luta can be considered to be not totally consistent with elevated salinity at these times because they are considerably lower than the mean of nonevaporative units such as the Eiss Member in the Council Grove Group (-0.89‰). If there indeed is a salinity signal embedded in these oxygen isotope data, then it can not be independently resolved.
the reverse. Mean sea water temperatures were estimated from mean δ18O values using the equation in Hays and Grossman (1991), assuming 0‰ (vs SMOW) for sea water δ18O in an ice-house world such as existed during the late Carboniferous to early Permian (Veevers 1994). Estimated mean temperatures generally increase during transgression and decrease during subsequent regression (Fig. 4), a trend that is opposite that, for example, in Pennsylvanian rocks in Texas (Adlis et al. 1988; Grossman et al. 1991). Furthermore, estimated temperatures range from 19o to 32oC, with seemingly cool water during deposition of the Eiss Member (20oC), the upper part of the Fort Riley Formation (22oC), and the Herington Member (19oC). Comparison to the temperature-depth profile in analogous modern tropical seas north of Australia (Adlis et al. 1988), for example, would suggest water depths of approximately 130-150 m for these units, which is not likely considering their warm, shallow-water biotic and sedimentologic characteristics. Estimated temperatures would be even cooler if we assume a sea water δ18O value of -1.2‰, which represents a modern ocean on an ice-free Earth.
Carbon Isotope Stratigraphy Brachiopods such as Composita were epifaunal, stenohaline organisms (Fürsich and Hurst 1974). Hence, the δ13C values of their shells are assumed to reflect the δ13C of dissolved inorganic carbon (DIC) in sea water, and should be insensitive to temperature change (Romanek et al. 1972). The temporal δ13C trend in the Council Grove and Chase Groups does not track the δ18O trend in its relationship to cyclicity in the section (Fig. 4). Rather, δ13C values progressively decrease through the Council Grove cycle and into the basal cycle in the Chase Group, and then the pattern repeats from there to the top of the middle cycle in the Chase Group. Carbon isotope values in the upper cycle also follow this pattern except that they then increase at the top. These trends transect transgressive and regressive phases of the depositional cycles, and hence, support our contention that the Composita samples generally are from
The mean δ18O trend does not appear to reflect changes in sea water temperature. Rather, we contend that the dominant influence on brachiopod δ18O values instead was sea water δ18O, wherein δ18Osw increased during glacial buildup and decreased during melting (e.g., Fairbanks and Matthews 1978; Anderson and Arthur 1983). A departure from the general δ18O trend occurs in the Krider Member near the top of the Chase Group, wherein mean δ18O values decrease (Fig. 4). This excursion may reflect local micro-habitat effects. Despite our attempt to sample from similar paleoenvironments, temporal variations in the salinity of shallow sea water can not be totally ruled out as at least partly contributing to the 65
IMPLICATIONS FOR SEA WATER CHEMISTRY AND DEPOSITIONAL CYCLICITY layer of the Pennsylvanian ocean. Some carbon isotope fractionation between ambient sea water and growing shells is indicated in modern and fossil brachiopods (Wefer and Berger 1991). A constant δ13C enrichment of about 1.0 ±0.4‰, for example, was documented in Pennsylvanian Composita relative to other co-occurring brachiopods (Grossman et al. 1991, 1993). These data suggest that variations in the δ13C of Composita shells (Fig. 4) provide a record of variations in sea water δ13C values. Such variations in shell δ13C values could be a response to global changes in sedimentary organic carbon and biomass productivity budgets, or to changes in paleoceanographic configurations (Anderson and Arthur 1983). The available data (Fig. 4) do not permit us to fully evaluate these parameters. Possible effects induced by upwelling during deposition of the Chase Group and upper part of the Council Grove can be eliminated because the nearby, previously deep Anadarko Basin to the south had become an area of shallow-water deposition by this time (Rascoe and Adler 1983). Some phosphatic black shales that presumably are indicative of upwelling are present in the lower and middle Council Grove, but δ13C variations in otherwise high values are very low (1‰) in this part of the section. In contrast, more pronounced variations (several ‰) occur in overlying rocks where there is no evidence of upwelling (Fig. 4). DISCUSSION Cyclicity and Glaciation The inference of ice accumulation as a fundamental control on brachiopod and sea water δ18O cyclicity in the Council Grove and Chase Groups (upper Gzhelian to Artinskian) is in accordance with interpreted glacio-eustatic forcing of depositional cyclicity in this section (Boardman et al. 1995; Mazzullo 1998, 1999a). Although the brachiopod and sea water δ18O record of older midcontinent Pennsylvanian strata (Kasimovian to middle Gzhelian) likewise indicates such forcing, the positive correlation in these rocks between δ18O and paleowater depth is explained by sea water temperature variations associated with pronounced depth changes rather than by ice-volume effects (Adlis et al. 1988; Grossman et al. 1991). Mean δ18O values in pre- and postmiddle Gzhelian strata reflect these apparent contrasting controls such that little to no sea water δ18O cyclicity is evident in the older part of the section regardless of whether Composita or other brachiopod data are considered (Fig. 5). Such disparity may be related to either the different scales of depositional cyclicity sampled herein versus elsewhere in the midcontinent (Adlis et al. 1988; Grossman et al. 1991, 1993), or to the relative amplitudes of sea-level fluctuations during the Pennsylvanian and early Permian.
Figure 3. Mole % MgCO3 versus δ18O (A), and crossplot of δ18O and δ13C values (B) in altered and unaltered Composita. C. Cross-plot of δ18O and δ13C values of the primary prismatic and secondary fibrous shell layers in individual samples of unaltered Composita. Sample numbers are indicated for reference to Table 1. uniform paleowater depths. Grossman et al. (1993) did not observe clear relationship between oxygen and carbon isotope values and paleowater depth based on analysis of Pennsylvanian Composita samples from Kansas. They speculated that their samples possibly were from the mixed
It is not possible, for example, to determine if our oxygen isotope data also would have tracked temperatures attending 66
MAZZULLO, BOARDMAN, GROSSMAN, AND DIMMICK-WELLS
Figure 4. Temporal trends in δ18O and δ13C values of unaltered Composita relative to cyclicity; TST = transgressive systems tract, HST = highstand systems tract. Temperature range (± 1 standard deviation) is estimated based on mean δ18O values of brachiopods using δ18Osw = 0‰ vs SMOW. Expected temperature trend also shown (no scale indicated). Estimated amplitudes of glacio-eustatic fluctuations involving low-frequency cycles in the Council Grove and upper Chase Group are indicated within vertical, double-tipped arrows in the δ18O column. Note apparent increases in δ18O values during deposition of regressive sections, with high values toward the end of these times. higher-frequency depositional cyclicity as was noted elsewhere in the midcontinent. The reason for this is because
specimens of Composita from maximum transgressive deposits are not available in Council Grove and Chase 67
IMPLICATIONS FOR SEA WATER CHEMISTRY AND DEPOSITIONAL CYCLICITY
Figure 5. δ18O and δ13C trends in the Upper Pennsylvanian to Lower Permian in North America based on brachiopods and marine cements; no vertical or temporal scales are intended. Error bars (±2 standard error) are shown for data in the Chase and Council Grove Groups. Composita and other brachiopod data in the Missourian and lower Virgilian are from Adlis et al. (1988) and Grossman et al. (1991, 1993). Italicized formations/members are units for which data are available. Correlation of Kansas and Texas units is from Boardman and Heckel (1989). Ranges of means for marine cement data from Davies and Krouse (1975) and Davies (1977) are shown. 68
MAZZULLO, BOARDMAN, GROSSMAN, AND DIMMICK-WELLS Artinskian (Fig. 5). The overall trend toward higher δ18O values likely is a signal of long-term increase in aridity and salinity (Railsback et al. 1989) as has been inferred for nearequatorial regions in midcontinent Pangea at this time (e.g., Parrish 1993). As discussed above, evidence of increasing salinity and aridity are present in outcrops of the Chase Group (Mazzullo 1998, 1999a; Mazzullo et al. 1997).
Group strata for comparison to shallow-water specimens. On the other hand, if δ18Osw increased by ~1‰ per 100 m of sea-level drop as during the Pleistocene (Fairbanks and Matthews 1978), then uncorrected amplitudes of sea-level fluctuations of the low-frequency cycles in the Council Grove and Chase Groups may have been on the order of 110-150 m (Fig. 4). In fact, fluctuations of as much as 200 m have been suggested for rocks of this age elsewhere in North America (Ross and Ross 1987; Mazzullo 1997). In contrast, estimated amplitudes of various orders of depositional cyclicity are less for the Kasimovian to middle Gzhelian, and range from 30-70 m (Wilson 1967; Adlis et al. 1988; Goldstein 1988) to 50-100 m (Heckel 1977; Grossman et al. 1991; Soreghan and Giles 1999). Crowley and Baum (1991) suggested a figure of about 60 m for the Bashkirian to Moscovian (lower Pennsylvanian) based on presumed ice sheet area-volume estimates. Hence, the amplitude of sea-level fluctuations appears to have increased over time, which is consistent with maximum Gondwanan glaciation and possibly maximum sea-level fluctuations during the latest Pennsylvanian to early Permian (Dickins 1985; Veevers and Powell 1987; Crowell 1995).
The significance of contrasting estimates of δ18Osw values based on various brachiopods versus marine cements in Kasimovian to middle Gzhelian strata is discussed in Grossman (1994) and Grossman et al. (1993). Some marine cement data are available only for correlative Council Grove Group strata (Fig. 5). The range of mean δ18O values of cements from New Mexico (Graber 1989) and Canada (Davies and Krouse 1975), for example, are consistently lower than that based on the Kansas and Oklahoma brachiopods, suggesting diagenetic and/or local temperature/salinity effects. The highest δ18O and δ13C values reported by Davies and Krouse (1975), however, overlap those of brachiopods in the basal Council Grove and older Pennsylvanian strata in Kansas, Oklahoma, and Texas, and they likely represent least-altered cements. Such coincidence at least partly corroborates inferences of estimated ocean δ18O-δ13C values in Upper Pennsylvanian to Lower Permian rocks based on these brachiopods. The δ13C ranges of marine cements and brachiopods from Canada (Davies 1977; Beauchamp et al. 1987; Graber 1989; Mii et al. 1999) are higher than those of brachiopods in the Council Grove Group and similar to values for samples from Russia and Spain (Popp et al. 1986; Mii et al. 2001), which possibly suggests a physical connection between the Sverdrup Basin and the Paleotethys Ocean.
Furthermore, the 110-150 m estimate for sea-level fluctutations in the Council Grove and Chase Groups suggests that the extent of glaciation during the latest Pennsylvanian to early Permian may have been similar to that during the Pleistocene (e.g., Crawley and Baum 1991). It is possible that the δ18O trends in the tropical marine deposits studied in this paper, and in Adlis et al. (1988) and Grossman et al. (1991, 1993), reflect temperature effects when sea-level fluctuations are relatively low and ice-volume effects when fluctuations are relatively high. Alternatively, it is possible that ice-volume effects in the Kasimovian to middle Gzhelian were overprinted by temperature effects because of upwelling, the intensity of which decreased dramatically in post-middle Gzhelian time because of filling of the Anadarko Basin.
CONCLUSIONS The Council Grove and Chase Groups (upper Gzhelian to lower Artinskian: Upper Pennsylvanian to Lower Permian) in Kansas and Oklahoma comprise cyclic, shallow-marine and terrestrial facies deposited on a gently dipping ramp in a tropical, low-latitude setting. Highest-frequency cyclothems in the section are grouped into lower-frequency cycles of marine carbonate and shale bounded by terrestrial redbeds and paleosols. In unaltered samples of the spiriferid brachiopod Composita collected from these rocks, mean MgCO3 content and δ18O and δ13C values are 0.2 mole %, -2.1‰, and 4.0‰, respectively.
Temporal Changes and Correlation to Marine Cement Data Although the cause of the shifts in δ18O values in the lower Gzhelian (Fig. 5) is not known with certainty, the shifts may reflect initial transition from temperature-dominated to ice volume-dominated controls on the chemostratigraphic record attending changing magnitudes and amplitudes of glacio-eustatic sea-level fluctuations. The specific mechanism responsible for such changes, however, is not readily apparent. Notwithstanding the gap in data for most of the upper Gzhelian, it appears that the mean brachiopod δ18O value based on either Composita or other genera from Kansas, Oklahoma, and Texas remained nearly constant at about -2.0‰ from the Kasimovian into the middle Gzhelian. Then the mean value decreased slightly to about -2.3‰ in the uppermost Gzhelian to Asselian before eventually increasing to as high as about -0.6‰ by the early
Stratigraphic trends in brachiopod δ18O values in the Council Grove and Chase Groups do not appear to reflect decreases in paleo-sea water temperature with increasing depth as they do in older Pennsylvanian cyclic deposits in Texas. Instead, they grossly track low-frequency depositional cycles, which suggests ice-volume accumulation as the dominant influence on brachiopod and sea water δ18O, possibly with an embedded signal of salinity variations over time. In contrast, there are no significant long-term trends in 69
IMPLICATIONS FOR SEA WATER CHEMISTRY AND DEPOSITIONAL CYCLICITY brachiopod δ13C or correlation between brachiopod δ13C and low-frequency cyclicity. Mean δ18O trends confirm glacioeustasy as a fundamental control on depositional cyclicity, and may suggest: (1) sea-level fluctuations of about 110150 m, which appear to have been greater than those during the earlier Pennsylvanian; (2) that the extent of Gondwanan glaciation was analogous to that during the Pleistocene, and reached a maximum during the latest Pennsylvanian and early Permian; and (3) that ice-volume accumulation effects are dominantly reflected in the oxygen isotopic record at times of relatively high sea-level fluctuations, whereas temperature effects are dominantly recorded in the signal when such fluctuations are lower.
Geosciences Section), v. 65, p. 117-136. BRUCKSCHEN, P., OESMANN, S., and VEIZER, J., 1999, Isotope stratigraphy of the European Carboniferous. Proxy signals for ocean chemistry, climate, and tectonics: Chemical Geology, v. 161, p. 127-163. CARPENTER, S.J. and LOHMANN, K.C., 1995, δ18O and δ13C values of modern brachiopod shells: Geochimica et Cosmochimica Acta, v. 59, p. 3749-3764. CARPENTER, S.J., LOHMANN, K.C., HOLDEN, P., WALTER, L.M., HUSTON, T.J., and HALLIDAY, A.N., 1991, δ18O values 87Sr/86Sr and Sr/Mg ratios of Late Devonian abiotic marine calcite: implications for the composition of ancient seawater: Geochimica et Cosmochimica Acta, v. 55, p. 1991-2010. CLIMAP, 1981, Seasonal reconstructions of the Earth’s surface at the last glacial maximum: Geological Society of America Map and Chart Series, no. MC-36, 18 p. COMPSTON, W., 1960, The carbon isotopic composition of certain marine invertebrates and coals from the Australia Permian: Geochimica et Cosmochimica Acta, v. 18, p. 122. CROWELL, J.C., 1995, The ending of the late Paleozoic ice age during the Permian Period, in P.A. Scholle, T.M. Peryt, and D.S. Ulmer-Scholle, eds., The Permian of Northern Pangea, Berlin, Springer-Verlag, v. 1, p. 62-74. CROWLEY, T.J. and BAUM, S.K., 1991, Estimating Carboniferous sea-level fluctuations from Gondwanan ice extent: Geology, v. 19, p. 975-977. DAVIES, G.R., 1977, Former magnesian calcite and aragonite submarine cements in upper Paleozoic reefs of the Canadian Arctic: a summary: Geology, v. 5, p. 11-15. DAVIES, G.R. and KROUSE, H.R., 1975, Carbon and oxygen isotopic composition of Late Paleozoic calcite cements, Canadian Arctic Archipelago - preliminary results and interpretation: Geological Survey of Canada Paper, no. 751, Part B, p. 215-220. DICKINS, J.M., 1985, Late Paleozoic glaciation: BMR Journal of Australian Geology and Geophysics, v. 9, p. 163-169. DICKSON, J.A.D., SMALLEY, P.C., and KIRKLAND, B.L., 1991, Carbon and oxygen isotopes in Pennsylvanian biotic and abiogenic aragonite (Otero County, New Mexico): a laser microprobe study: Geochimica et Cosmochimica Acta, v. 55, p. 2607-2613. FAIRBANKS, R.G. and MATTHEWS, R.K., 1978, The marine oxygen isotope record in Pleistocene coral, Barbados, West Indies: Quaternary Research, v. 10, p. 181-196. FURSICH, F.T. and HURST, J.M., 1974, The environmental factors determining the distribution of brachiopods: Palaeontology, v. 17, p. 879-900. GALIMOV, E.M., MIGDISOV, A.A., and RONOV, A.B., 1975, Variation in the isotopic composition of carbonate and organic carbon in sedimentary rocks during Earth’s history: Geochemistry International, v. 12, p. 1-19. GIVEN, R.K. and LOHMANN, K.C., 1985, Spatial and temporal controls on the variation of original isotopic compositions of Permian marine carbonates: Journal of Sedimentary Petrology, v. 55, p. 430-439. GIVEN, R.K. and LOHMANN, K.C., 1986, Isotopic evidence for the early meteoric diagenesis of the reef facies, Permian reef complex of west Texas and New Mexico: Journal of Sedimentary Petrology, v. 56, p. 183-193. GOLDSTEIN, R.H., 1988, Cement stratigraphy of Pennsylvanian Holder Formation, Sacramento Mountains, New Mexico:
ACKNOWLEDGEMENTS This research was supported by grants to the senior author from the Office of the Vice President for Research, Wichita State University, and from several petroleum industry contracts. We gratefully acknowledge the comments and critiques of the original manuscript by Fred Read and Carl Drummond. REFERENCES ADLIS, D.S., GROSSMAN, E.L., YANCY, T.E., and MCLERRAN, R.D., 1988, Isotope stratigraphy and paleodepth changes of Pennsylvanian cyclic sedimentary deposits: Palaios, v. 3, p. 487-506. AL-AASM, I.S. and VEIZER, J., 1982, Chemical stabilization of low-Mg calcite: an example of brachiopods: Journal of Sedimentary Petrology, v. 52, p. 1101-1109. ANDERSON, T.F. and ARTHUR, M.A., 1983, Stable isotopes of oxygen and carbon and their application to sedimentologic and paleoenvironmental problems, in M.A. Arthur, T.F. Anderson, I.R. Kaplan, J. Veizer, and L.S. Land, eds., Stable Isotopes in Sedimentary Geology: SEPM Short Course, no. 10, Tulsa, p. 1-151. BEAUCHAMP, B., OLDERSHAW, A.E., and KROUSE, H.R., 1987, Upper Carboniferous to Upper Permian 13C-enriched primary carbonates in the Sverdrup Basin, Canadian Arctic: comparisons to coeval western North American ocean margins: Chemical Geology (Isotope Geoscience Section), v. 65, p. 391-413. BOARDMAN, D.R. and HECKEL, P.H., 1989, Glacial eustatic sea-level curve for early Late Pennsylvanian sequence in north-central Texas and biostratigraphic correlation with curve for midcontinent North America: Geology, v. 17, p. 802-805. BOARDMAN, D.R., NESTELL, M.K., and KNOX, L.W., 1995, Depth-related microfaunal biofacies model for Late Carboniferous and Early Permian cyclothemic sedimentary sequences in midcontinent North America, in N.J. Hyne, ed., Sequence Stratigraphy of the Mid-Continent: Tulsa Geological Society Special Publication, no. 4, p. 93-118. BRAND, U., 1982, The oxygen and carbon isotope composition of Carboniferous fossil components: sea-water effects: Sedimentology, v. 29, p. 139-147. BRAND, U., 1987, Depositional analysis of the Breathit Formation’s marine horizons, Kentucky, U.S.A.: trace elements and stable isotopes: Chemical Geology (Isotope
70
MAZZULLO, BOARDMAN, GROSSMAN, AND DIMMICK-WELLS America and consideration of some possible tectonic effects, in J.M. Dennison and F.R. Ettensohn, eds., Tectonic and Eustatic Controls on Sedimentary Cycles: SEPM (Society for Sedimentary Geology) Concepts in Sedimentology and Paleontology, v. 4, p. 65-87. LEPZELTER, C.G., ANDERSON, T.F., and SANDBERG, P.A., 1983, Stable isotope variation in modern articulate brachiopods: American Association of Petroleum Geologists Bulletin, v. 67, p. 500-501. LOHMANN, K.C. and WALKER, J.C.G., 1989, The δ18O record of Phanerozoic abiotic marine calcite cements: Geophysical Research Letters, v. 16, p. 319-322. LOWENSTAM, H.A., 1961, Mineralogy, 18O/16O ratios, and strontium and magnesium contents of recent and fossil brachiopods and their bearing on the history of the oceans: Journal of Geology, v. 69, p. 241-260. MACKENZIE, F.T., BISCHOFF, W.D., BISHOP, F.C., LOIJENS, M., SCHOONMAKER, J., and WOLLAST, R., 1983, Magnesian calcites: low temperature occurrence, solubility and solid-solution behavior: Mineralogical Society of America: Reviews in Mineralogy, v. 11, p. 97-144. MAGARITIZ, M. and HOLSER, W.T., 1990, Carbon isotope shifts in Pennsylvanian seas: American Journal of Science, v. 290, p. 977-994. MAZZULLO, S.J., 1997, Stratigraphic exploration plays in Ordovician to Lower Permian strata in the Midland Basin and on the Eastern Shelf, in W.D. DeMis, ed., Permian Basin Oil and Gas Fields - Turning Ideas into Production: West Texas Geological Society Publication, no. 97-102, p. 1-37. MAZZULLO, S.J., 1998, Stratigraphic architecture of Lower Permian cyclic carbonate reservoirs (Chase Group) in the mid-continent USA, based on outcrop studies: American Association of Petroleum Geologists Bulletin, v. 82, p. 464483. MAZZULLO, S.J., 1999a, Eustatic and tectonic controls on cyclic deposition in Lower Permian ramp facies (Chase Group and basal Wellington Formation) in the U.S. Midcontinent, in P.M. Harris, A.H. Saller, and J.A. Simo, eds., Advances in Carbonate Sequence Stratigraphy: Application to Reservoirs, Outcrops, and Models. SEPM Special Publication, no. 63, p. 151-168. MAZZULLO, S.J., 1999b, Paleoenvironments, cyclicity, and diagenesis in the outer shelf Tansill Formation in the Carlsbad Embayment (Dark Canyon), northern Guadalupe Mountains, New Mexico, in A.H. Saller, P.M. Harris, B. Kirkland, and S.J. Mazzullo, eds., Geologic Framework of the Capitan Reef. SEPM Special Publication, no. 65, p. 107128. MAZZULLO, S.J., TEAL, C.S., and BURTNETT, C.A., 1997, Outcrop stratigraphy and depositional facies of the Chase Group (Permian, Wolfcampian) in Kansas and southeastern Nebraska: Kansas Geological Survey Technical Series, v. 6, 210 p. MII, H-S. and GROSSMAN, E.L., 1994, Late Pennsylvanian seasonality reflected in the stable isotope and elemental composition of a brachiopod shell: Geology, v. 22, p. 661664. MII, H-S., GROSSMAN, E.L., and YANCEY, T.E., 1999, Carboniferous isotope stratigraphies of North America: implications for Carboniferous paleoceanography and Mississippian glaciation: Geological Society of America Bulletin, v. 111, p. 960-973.
American Association of Petroleum Geologists Bulletin, v. 72, p. 425-438. GOLONKA, J., ROSS, M.I., and SCOTESE, C.R., 1994, Phanerozoic paleogeographic and paleoclimatic modeling maps, in A.F. Embry, B. Beauchamp, and D.J. Glass, eds., Pangea - Global Environments and Resources: Canadian Society of Petroleum Geologists Memoir, no. 17, p. 1-47. GRABER, E.R., 1989, Sedimentology, diagenesis, and secular δ13C variations in the upper Horquilla limestone (Pennsylvanian/ Permian) of New Mexico. Unpublished PhD dissertation, University of Michigan, Ann Arbor, 276 p. GRINNELL, R.S. and ANDREWS, G.W., 1964, Morphologic studies of the brachiopod genus Composita: Journal of Paleontology, v. 38, p. 227-248. GROSSMAN, E.L., 1994, The carbon and oxygen isotope record during the evolution of Pangea: Carboniferous to Triassic, in G.D. Klein,, ed., Pangea: Paleoclimate, Tectonics, and Sedimentation During Accretion, Zenith, and Breakup of a Supercontinent: Geological Society of America, Boulder, Colorado Special Paper, no. 288, p. 207-228. GROSSMAN, E.L. and KU, T-L., 1986, Oxygen and carbon isotope fractionation in biogenic aragonite: temperature effects: Chemical Geology (Isotope Geoscience Section), v. 59, p. 59-74. GROSSMAN, E.L., MAZZULLO, S.J., YANCEY, T.E., and MII, H-S., 2001a, A 70-million-year record of δ18O variation in the Permo-Carboniferous: implications for seawater δ18O: 11th Annual V.M. Goldschmidt Conference, Abstract # 3822, LPI Contribution #1088, Lunar and Planetary Institute, Houston (on CD-ROM). GROSSMAN, E.L., MAZZULLO, S.J., YANCEY, T.E., and MII, H-S., 2001b, An 85-million-year record of carbon isotopic variation in the Permo-Carboniferous: implications for carbon cycling and paleoclimate; Programs with Abstracts, Geological Society of America and Geological Society of London (Special Session on Earth System Processes Global Meeting), p. 70-71. GROSSMAN, E.L., MII, H-S., and YANCEY, T.E., 1993, Stable isotopes in Late Pennsylvanian brachiopods from the United States: implications for Carboniferous paleoceanography: Geological Society of America Bulletin, v. 105, p. 12841296. GROSSMAN, E.L., MII, H-S., and YANCEY, T.E., 1996, Chemical variation in Pennsylvanian brachiopod shells diagenetic, taxonomic, microstructural, and seasonal effects: Journal of Sedimentary Research, v. 66, p. 1011-1022. GROSSMAN, E.L., ZHANG, C., and YANCEY, T.E., 1991, Stable-isotope stratigraphy of brachiopods from Pennsylvanian shales in Texas: Geological Society of America Bulletin, v. 103, p. 953-965. GUILDERSON, T.P., FAIRBANKS, R.G., and RUBENSTONE, J.L., 1994, Tropical temperature variations since 20,000 years ago: modulating interhemispheric climate change: Science, v. 263, p. 663-665. HAYS, P.D. and GROSSMAN, E.L., 1991, Oxygen isotopes in meteoric calcite cements as indicators of continental climate: Geology, v. 19, p. 441-444. HECKEL, P.H., 1977, Origin of phosphatic black shales facies in Pennsylvanian cyclothems of midcontinent North America: American Association of Petroleum Geologists Bulletin, v. 61, p. 1045-1068. HECKEL, P.H., 1994, Evaluation of evidence for glacio-eustatic control over marine Pennsylvanian cyclothems in North
71
IMPLICATIONS FOR SEA WATER CHEMISTRY AND DEPOSITIONAL CYCLICITY SCOTESE, C.R. and McKERROW, W.S., 1990, Revised world maps and introduction, in W.S. McKerrow and C.R. Scotese, eds., Palaeozoic Palaeogeography and Biogeography: Geological Society of London Memoir, no. 12, p. 1-21. SOREGHAN, G.S. and GILES, K.A., 1999, Amplitudes of late Pennsylvanian glacioeustasy: Geology, v. 27, p. 255-258. THAYER, C.W., 1981, Ecology of living brachiopods, in T.W. Broadhead, ed., Lophophorates, Notes for a Short Course: University of Tennessee, Department of Geological Sciences, Studies in Geology, no. 5, p. 110-126. VEEVERS, J.J., 1994, Pangea: evolution of a supercontinent and its consequences for Earth’s paleoclimate and sedimentary environments, in G.D. Klein, ed., Pangea: Paleoclimate, Tectonics, and Sedimentation During Accretion, Zenith, and Breakup of a Supercontinent: Geological Society of America Special Paper, Boulder, Colorado, no. 288, p. 1323. VEEVERS, J.J., CONAGHAN, P.J., and SHAW, S.E., 1994, Turning point in Pangean environmental history at the Permian/Triassic (R/Tr) boundary, in G.D. Klein, ed., Pangea: Paleoclimate, Tectonics, and Sedimentation During Accretion, Zenith, and Breakup of a Supercontinent: Geological Society of America Special Paper, Boulder, Colorado, no. 288, p. 187-196. VEEVERS, J.J. and POWELL, C.M., 1987, Late Paleozoic glacial episodes in Gondwanaland reflected in transgressiveregressive depositional sequences in Euramerica: Geological Society of America Bulletin, v. 98, p. 475-487. VEIZER, J. and HOEFS, J., 1976, The nature of 18O/16O and 13C/12C secular trends in sedimentary carbonate rocks: Geochimica et Cosmochimica Acta, v. 40, p. 1387-1395. VEIZER, J., HOLSER, W.T., and WILGUS, C.K., 1980, Correlation of 13C/12C and 34S/32S secular variations: Geochimica et Cosmochimica Acta, v. 44, p. 579-587. WEFER, G. and BERGER, W.H., 1991, Isotope paleontology: growth and composition of extant calcareous species: Marine Geology, v. 100, p. 207-248. WIGGINS, W.D., 1986, Geochemical signatures in carbonate matrix and their relation to deposition and diagenesis, Pennsylvanian Marble Falls Limestone, central Texas: Journal of Sedimentary Petrology, v. 56, p. 771-783. WILSON, J.L., 1967, Cyclic and reciprocal sedimentation in Virgilian strata of southern New Mexico: Geological Society of America Bulletin, v. 78, p. 805-818.
MII, H-S., GROSSMAN, E.L., YANCEY, T.E., CHUVASHOV, B., and EGOROV, A., 2001, Isotopic records of brachiopod shells from the Russian Platform - evidence for the onset of Mid-Carboniferous glaciation: Chemical Geology, v. 175, p. 133-147. MORRISON, J.O., BRAND, U., and ROLLINS, H.B., 1985, Paleoenvironmental and chemical analysis of the Pennsylvanian Brush Creek fossil allochems, Pennsylvania, U.S.A. 10th International Congress on Carboniferous Stratigraphy and Geology, v. 2, p. 271-280. MRUK, D.H., 1989, Diagenesis of the Capitan limestone, upper Permian, McKittrick Canyon, west Texas, in P.M. Harris and G.A. Grover, eds., Subsurface and Outcrop Examination of the Capitan Shelf Margin, Northern Delaware Basin: SEPM Core Workshop, no. 13, p. 387-406. OLSZEWSKI, T.D. and PATZKOWSKY, M.E., 2003, From cyclothems to sequences: the record of eustasy and climate on an icehouse epeiric platform (Pennsylvanian-Permian, North American midcontinent): Journal of Sedimentary Research, v. 73, p. 15–30. PARRISH, J.T., 1993, Climate of the supercontinent Pangea: Journal of Geology, v. 101, p. 215-233. POPP, B.N., 1986, The record of carbon, oxygen, sulfur, and strontium isotopes and trace elements in late Paleozoic brachiopods. Unpublished PhD dissertation, University of Illinois Urbana, 199 p. POPP, B.N., ANDERSON, T.F., and SANDBERG, P.A., 1986a, Brachiopods as indicators of original isotopic compositions in some Paleozoic limestones: Geological Society of America Bulletin, v. 97, p. 1262-1269. POPP, B.N., ANDERSON, T.F., and SANDBERG, P.A., 1986b, Textural, elemental, and isotopic variations among constituents in Middle Devonian limestones, North America: Journal of Sedimentary Petrology, v. 56, p. 715-727. RAILSBACK, L.B., ANDERSON, T.F., ACKERLY, S., and CISNE, J.L., 1989, Paleoceanographic modeling of temperature-salinity profiles from stable isotopic data: Paleoceanography, v. 4, p. 585-591. RASCOE, B. and ADLER, F.J., 1983, Permo-Carboniferous hydrocarbon accumulations, mid-continent, U.S.A.: American Association of Petroleum Geologists Bulletin, v. 67, p. 979-1001. ROMANEK, C.S., GROSSMAN, E.L., and MORSE, J.W., 1992, Carbon isotopic fractionation in synthetic aragonite and calcite: effects of temperature and precipitation rate: Geochimica et Cosmochimica Acta, v. 56, p. 419-430. ROSS, C.A. and ROSS, J.R.P., 1987, Late Paleozoic sea levels and depositional sequences, in C.A. Ross and D. Haman, eds., Timing and Depositional History of Eustatic Sequences: Contraints on Seismic Stratigraphy: Cushman Foundation for Foraminiferal Research Special Publication, no. 24, p. 137-149. RUSH, P.F. and CHAFETZ, H.S., 1990, Fabric-retentive, nonluminescent brachiopods as indicators of original δ13C and δ18O compositions: a test: Journal of Sedimentary Petrology, v. 60, p. 968-981.
72
