Browsing by Subject "Conodonts"
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Item Applications of conodonts in resolving Pennsylvanian-Permian stratigraphic problems in north-central Texas, New Mexico, Colorado, and Kansas(Texas Tech University, 2002-08) Keairns, Carter EwingPennsylvanian-Permian strata of midcontinent North America comprise numerous cyclothems that are the result of repetitive sea-level changes that produced multiple alternations of marine and non marine facies. Placement of chronostratigraphic boundaries within cyclothems is problematic because the variations in sea-level do not allow a continuous representation of marine facies. This creates gaps in the faunal (and floral) record across potential series and stage boundary intervals. Conodont faunas were collected from localities in north-central Texas, Kansas, Oklahoma, and the Sacramento Mountains of New Mexico. These collections were analyzed for biostratigraphically significant faunas that could delineate, with greater resolution, the Late Pennsylvanian Missourian-Virgilian Boundary. Size criteria, in particular the use of adults not juveniles for index species is addressed, determining that indeed size does matter, and that adult forms are the only platforms that should be considered as biostratigraphically significant. Two new morphotypes of Streptognathodus, Streptognathodus sp. C and Streptognathodus sp. D were identified on the basis of carina length and termination relative to platform length. These new morphotypes combined with existing species Streptognathodus firmus, Streptognathodus pawhuskaensis, and Idiognathus simulator, were sufficient to develop diagnostic faunal zones across the boundary interval. Correlations were based on first appearances of three streptognathodid species, and then a second level of confidence obtained with percentages of species in successive faunas. The newly developed zonations was successfully used to correlate the Stanton, South Bend, and Iatan cycles of midcontinent Kansas with the Upper Winchell, Placid- Ranger dual cycle, and Colony Creek of north-central Texas. The new zonation was extended into New Mexico permitting correlation of the Missourian-Virgilian boundary strata (South Bend cycle) near cycle 2C-5a (of Raatz). The majority of Dry Canyon samples were stratigraphically above the boundary, as evidenced by the presence of the conodont I. lohatulus, and two forms of S. virgilicus that resemble the new morphotypes S. sp C and S. sp. D. It appears as though the trend of a shortening carina, that was useful at the Missourian-Virgilian boundary may 'reset' and repeat itself higher in the Virgilian. In Central Colorado, conodont collections from the Kerber and Sharpsdale formations (Morrowan- Atokan) were assessed for possible biostratigraphic correlation to other regions of Colorado. The carbonates of the upper Kerber and lower Sharpsdale are latest Morrowan based on the conodont data. Recommendations are to sample the Central Colorado equivalent, the Belden Shale for additional, and hopefully, diagnostic conodont faunas.Item Conodont Biostratigraphy and Paleoecology of the Hegler and Pinery Members, of the Bell Canyon Formation (Permian) in the Delaware Basin of West Texas.(Texas Tech University, 1975-12) Sturm, John JNot Available.Item Conodont biostratigraphy of Devonian strata of West Texas and eastern New Mexico and the apparatus of early Devonian Icriodus species(Texas Tech University, 2002-08) Meyer, Beverly DianeDevonian strata in the Permian Basin reflect eperrogenic events and eustatic fluctuations in the southern midcontintent North America Changes in relative sea level demonstrated by conodont faunas and facies changes within the Frame, Thirtyone and Woodford Formations are compared to the Devonian qualitative eustatic curve. The lower Devonian (Lochkovian, woschmidit zone through omoalpha zone) conodont species Icriodus postwoschmidti Mashkova, 1968 occurs in carbonates of the Frame Formation in the Permian Basin and within the pre-Ia cycle of the eustatic curve. Icriodus claudiea Klapper, 1980 occurs in overlying carbonates and cherts of the Thirtyone Formation providing a Pragian (sulcatus to kindlei zone) age for the upper part of the formation and placing the Thirtyone in cycle Ia of the eustatic curve. Above the Thirtyone, green and gray clay shales at the base of the Woodford Formation produced an abundant Middle-Upper Devonian (Givetian-Frasnian) varcus to falsiovalis zone faima that ranges through cycle IIa into IIb of the sea-level curve. Typical Woodford black shales (Upper Devonian, Famennian) contain a crepida through expansa zone fauna of cycles IIe and IIf of the sea-level curve. No Mississippian conodont species were recovered from the Woodford Formation in the Permian Basin. Carbonate turbidites of the Dunple Limestone document headward erosion and transport of Woodford Formation deposits from the southern midcontment into a closing Ouachita ocean basm to the south or east during the Early Pennsylvanian. Four conodont faunas are described from reworked conodont elements recovered from the Dunple in the Marathon Uplift. Elements rangmg in age from Middle varcus Zone (Middle Devonian) to Lower crenulata Zone (Lower Mississippian) were admixed throughout the samples, with no original stratigraphic superposition preserved. The recovery of abundant elements of the Early Devonian species Icriodus postwoschmidti and I. claudiea from the Frame and Thutyone formations allows apparatus reconstmction and comparison of the morphological characteristics of the two species. Coryssognathus dubius (Rhodes, 1953) has been suggested as the most likely ancestor of Icriodus based on similar morphology of the non-Pa elements to those of the oldest species of the genus, I. woschmidti Ziegler, 1960. The apparatus reconstruction of I. postwoschmidti allows interpretation of changes in the apparatus that occurred between I. postwoschmidti and its ancestor species I. woschmidti, and suggests a relationship to C. dubius. Reconstruction of the apparatus of I claudiae allows comparison to both I. postwoschmidti and younger species and demonstrates continued morphological changes through time.Item Conodont biostratigraphy of the Montoya Group (Upper Ordovician) from the Mud Springs Mountains of south-central New Mexico(Texas Tech University, 1985-08) Evans, David GNot availableItem Conodont biostratigraphy of the Skinner Ranch and Hess Formations (Permian), Glass Mountains, West Texas(Texas Tech University, 1977-08) Carr, Timothy RNot availableItem Conodonts from the Glen Dean Formation of Kentucky and equivalent formations of Virginia and West Virginia(Texas Tech University, 1959-08) Clarke, Charles EdwardNot availableItem Conodonts from the Kinkaid Formation of the Illinois Basin(Texas Tech University, 1959-06) Burton, Robert CThe Kinkaid Formation is the uppermost unit in the Chester Series in the standard section for the Mississippian system in North America. The Kinkaid Formation crops out In the southwestern, southern, and southeastern margins of the Illinois Basin. The conodont fauna of the Kinkaid is distinctive, abundant, and varied. It can be correlated with the related conodont-ammonite zones in the Caney Shale In Oklahoma and, thereby, indirectly correlated with the Lower Namurian of Europe, which is differentiated on the basis of ammonites Detailed investigation of the Kinkaid conodont fauna suggests the following: 1. That the current move by the Illinois State Survey to establish a new member above the restricted Kinkaid formation is paleontologically sound, 2. That there v/as a restriction of the sea of Kinkaid time toward the vicinity of Johnson County, Illinois. 3. That there was a possible connecting seaway between the Illinois Basin and the Caney Shale area in the northern Arbuckles. The relatively greater abundance of conodonts recovered from limestone than from shale offers a clue to the paleoecology of conodont bearing creatures. This study establishes the Kinkaid conodont fauna in detail. New ranges are established for several forms. New species are described and Illustrated, occurrences noted, and faunal evaluations attempted.Item Conodonts of the Desmoinesian (middle Pennsylvanian) Lost Branch Formation, Oklahoma and Kansas(2005-05) Rosscoe, Steven J.; Barrick, Jim; Chatterjee, Sankar; Lehman, ThomasThe Lost Branch Formation of Oklahoma and Kansas was deposited during the last Desmoinesian (Middle Pennsylvanian) transgressive-regressive cycle of the Midcontinent Sea. The regression of the Midcontinent Sea during Lost Branch deposition records the final occurrences of the conodont genera Neognathodus and Swadelina as well as numerous ammonoids, the Desmoinesian brachiopod Mesolobus, the fusulinid Beedina, and some sponges and palynomorphs. The Lost Branch Formation begins at the top of the Dawson Coal in a sandy shale deposit of the Upper Holdenville Shale. The transgression of the Midcontinent Sea is recorded in the Upper Holdenville Shale, the Homer School Limestone, and the Nuyaka Creek Black Shale Bed. The regression of the Midcontinent Sea is recorded in the “offshore” Upper Holdenville Shale, the Glenpool Limestone, and the upper sandy shale deposit of the Upper Holdenville Shale. The lower outside shale is characterized by a conodont fauna of Idiognathodus species A, Adetognathodus lautus, and Idioprioniodus. As the transgression progressed there was further diversification of the fauna. The Homer School Limestone has the first appearance of Neognathodus dilatus dilatus, N. expansus expansus, and Hindeodus minutus. Specimens of I. expansus, Swadelina nodocarinata, N. dilatus bifurcatus, N. roundyi, N. expansus subspecies B, Gondolella magna, G. denuda, grooved morphotypes of I. expansus, and rounded and nodose morphotypes of Sw. nodocarinata are found in the overlying Nuyaka Creek Shale. The Nuyaka Creek Shale is the only interval where G. magna, G. denuda, and the rounded and nodose morphotypes of Sw. nodocarinata are recovered. The regression of the Midcontinent Sea is reflected in the conodont fauna by a loss of diversity. In the offshore shale of the Upper Holdenville Shale the conodonts Swadelina nodocarinata and Hindeodus minutus are absent. The Glenpool Limestone lacks the grooved morphotype of Idiognathodus expansus, Neognathodus dilatus dilatus, N. dilatus bifurcatus, N. roundyi, N. expansus expansus, N. expansus subspecies B, and Idioprioniodus. The only species found in the upper outside shale are I. expansus, I. species A, and Adetognathodus lautus. A paleoecological model for the Lost Branch Formation is presented that shows species tolerant of turbid waters living in the surface waters of the sea, and species preferring clear waters appearing only in the deeper offshore intervals. Gondolella and Swadelina dominate in clear-water assemblage, while Idiognathodus dominates in turbid waters. The well-preserved conodont fauna and easy clay-shale processing of the Lost Branch Formation provided an opportunity to study conodont Pa element function as it relates to microwear and element morphology. The original texture of blade denticles is fibrous, while the bar of the blade is smooth and featureless. The original texture of the platform forms a polygonal texture on the oral surface and a smooth texture on the aboral surface. Abrasive microwear removes original texture from the elements. Reshaping microwear takes element features, like denticles and ridges, and reshapes them into asymmetric surfaces indicative of their functional significance. By comparing the morphology of an element with the areas of intense microwear it was determined that the Pa element of Idiognathodus expansus served a food-processing and a food-transport function. The blade of the element pushed large food particles onto the ventral platform for crushing. The blade may also have sliced larger food particles. The ventral platform served a crushing and bruising function. The dorsal platform of the element pushed food back to the ventral platform for further processing.Item Conodonts of the Desmoinesian Lost Branch Formation, Oklahoma and Kansas(Texas Tech University, 2005-05) Rosscoe, Steven J.; Barrick, James E.; Chatterjee, Sankar; Lehman, ThomasThe Lost Branch Formation of Oklahoma and Kansas was deposited during the last Desmoinesian (Middle Pennsylvanian) transgressive-regressive cycle of the Midcontinent Sea. The regression of the Midcontinent Sea during Lost Branch deposition records the final occurrences of the conodont genera Neognathodus and Swadelina as well as numerous ammonoids, the Desmoinesian brachiopod Mesolobus, the fusulinid Beedina, and some sponges and palynomorphs. The Lost Branch Formation begins at the top of the Dawson Coal in a sandy shale deposit of the Upper Holdenville Shale. The transgression of the Midcontinent Sea is recorded in the Upper Holdenville Shale, the Homer School Limestone, and the Nuyaka Creek Black Shale Bed. The regression of the Midcontinent Sea is recorded in the “offshore” Upper Holdenville Shale, the Glenpool Limestone, and the upper sandy shale deposit of the Upper Holdenville Shale. The lower outside shale is characterized by a conodont fauna of Idiognathodus species A, Adetognathodus lautus, and Idioprioniodus. As the transgression progressed there was further diversification of the fauna. The Homer School Limestone has the first appearance of Neognathodus dilatus dilatus, N. expansus expansus, and Hindeodus minutus. Specimens of I. expansus, Swadelina nodocarinata, N. dilatus bifurcatus, N. roundyi, N. expansus subspecies B, Gondolella magna, G. denuda, grooved morphotypes of I. expansus, and rounded and nodose morphotypes of Sw. nodocarinata are found in the overlying Nuyaka Creek Shale. The Nuyaka Creek Shale is the only interval where G. magna, G. denuda, and the rounded and nodose morphotypes of Sw. nodocarinata are recovered. The regression of the Midcontinent Sea is reflected in the conodont fauna by a loss of diversity. In the offshore shale of the Upper Holdenville Shale the conodonts Swadelina nodocarinata and Hindeodus minutus are absent. The Glenpool Limestone lacks the grooved morphotype of Idiognathodus expansus, Neognathodus dilatus dilatus, N. dilatus bifurcatus, N. roundyi, N. expansus expansus, N. expansus subspecies B, and Idioprioniodus. The only species found in the upper outside shale are I. expansus, I. species A, and Adetognathodus lautus. A paleoecological model for the Lost Branch Formation is presented that shows species tolerant of turbid waters living in the surface waters of the sea, and species preferring clear waters appearing only in the deeper offshore intervals. Gondolella and Swadelina dominate in clear-water assemblage, while Idiognathodus dominates in turbid waters. The well-preserved conodont fauna and easy clay-shale processing of the Lost Branch Formation provided an opportunity to study conodont Pa element function as it relates to microwear and element morphology. The original texture of blade denticles is fibrous, while the bar of the blade is smooth and featureless. The original texture of the platform forms a polygonal texture on the oral surface and a smooth texture on the aboral surface. Abrasive microwear removes original texture from the elements. Reshaping microwear takes element features, like denticles and ridges, and reshapes them into asymmetric surfaces indicative of their functional significance. By comparing the morphology of an element with the areas of intense microwear it was determined that the Pa element of Idiognathodus expansus served a food-processing and a food-transport function. The blade of the element pushed large food particles onto the ventral platform for crushing. The blade may also have sliced larger food particles. The ventral platform served a crushing and bruising function. The dorsal platform of the element pushed food back to the ventral platform for further processing.Item Depositional environments, diagenesis, and conodont biostratigraphy of the Montoya Group (Late Ordovician), Sacramento Mountains, New Mexico(Texas Tech University, 1984-08) Brimberry, David LeeThe Montoya Group represents the southwestern exposure of sheet-like carbonate remnants of late Ordovician cratonic sediments. The central geologic location of the Sacramento Mountains in the Montoya Group distribution and excellent exposures of the strata provided an opportunity to analyze and interpret the depositional fabric, conodont biostratigraphy, and diagenetic sequences of the pervasively dolomitized and siliceous carbonates. The Montoya Group consists of three formations: Second Value, Aleman, and Cutter Dolomite. The Second Value is subdivided into the Cable Canyon and Upham Members. Conodont faunas aided in the interpretation and dating of depositional events for these formations. After an extended erosional period, middle Edenian transgressing seas deposited coarse-grained quartzose sand across the southwest sloping carbonate ramp. This thin sand bed, the Cable Canyon Member of the Second Value, was deposited in the upper wave-tidal, lower peritidal facies. The overlying Upham Member of the Second Value rests conformably on the Cable Canyon and was deposited in deepening, well-agitated water of the wave-tidal facies. Water depths continued to deepen in the Maysvillian as grain supported sediments were replaced by mud-dominated sediments in the Aleman Formation. Depositional environments shifted downdip to the open shelf facies. Shoaling conditions ended Aleman deposition with the early Richmondian south and west of the study area at this time. Following the short exposure, peritidal facies conditions developed and deposited the Cutter Dolomite during the Richmondian. A second exposure of the ramp ended Montoya deposition in the late Richmondian. Diagenetically, the Montoya underwent cyclic alteration after deposition. Dolomitization and sulfate emplacement affected the Second Value-Aleman succession during early burial and the Cutter penecontemporaneous with deposition. Exposure of these sediments at the end of the Second Value-Aleman and Cutter deposition respectively resulted in silicification, dissolution, and meteoric cementation. A second burial further dolomitized the units and emplaced sulfates. Recrystallization of the dolomite and cementation eliminated the early secondary porosity in the Montoya. Recrystallization and silicification were less pervasive in the Cutter Dolomite. Cenozoic deformation raised the Montoya from deep burial into another phase of freshwater diagenesis in meteoric phreatic and vadose environments. Most of the porosity found in the Montoya is a product of these diagenetic processes still active today.Item Stable isotope stratigraphy across the Silurian-Devonian boundary in southern Oklahoma and subsurface west Texas(Texas Tech University, 2004-12) Jacobi., David JosephStable isotopic ( 13C - ä 18O) analysis of carbonates from the Upper Silurian Henryhouse and Lower Devonian Haragan Formations in southern Oklahoma, and the Frame Formation (Upper Silurian-Lower Devonian) in southern Andrews County, Texas was conducted to determine if an excursion in ä 13C coincides with the shift in conodont faunal diversity that characterizes the Klonk event in Southwest Laurentia. Results show a gradual steady increase in ä13C (+ 1.0 %o) across the Henryhouse-Haragan boundary that reaches a peak value (~ + 3.0%o) in the early Lochkovian Icrodiuspostwoschmidti zone. The 5'^C signature of the Frame Formation also shows a steady increase in 5'^C (~ + 3.0 %o) from the late Pridoli that reaches a peak value (~+ 5.0 %o) in the early Lochkovian Icrodius postwoschmidti zone. The ä 13C chemostratigraphic curves do not exhibit an excursion at the level where conodont faunal diversity shifts at the Klonk event in the Henryhouse-Haragan or Frame formations. Intercontinental correlation of the data with other chemostratigraphic studies of Southern Gondwanan successions including the Global Stratotype Section and Point at Klonk in the Czech Republic, reveals no relationship between ä 13C and conodont faunal diversity as proposed by Jeppsson's (1990,1997,1998) model of Silurian Ocean cyclicity.