1,519 research outputs found

    Tempestites in a Teapot? Condensation-Generated Shell Beds in the Upper Ordovician, Cincinnati Arch, USA.

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    Skeletal concentrations in mudstones may represent local facies produced by storm winnowing in shallow water, or time-specific deposits related to intervals of diminished sediment supply. Upper Ordovician (Katian) of the Cincinnati region is a mixed siliciclastic-carbonate succession including meter-scale cycles containing a shelly limestone-dominated phase and a mudstone-dominated phase. The “tempestite proximality model” asserts that shell-rich intervals originated by winnowing of mud from undifferentiated fair-weather deposits. Thus shell beds are construed as tempestites, while interbedded mudstones represent either fair-weather or bypassed mud. Meter-scale cycles are attributed to sea-level fluctuation or varying storm intensity. Alternatively, the “episodic starvation model” argues, on the basis of petrographic, taphonomic, and stratigraphic evidence, that, despite widespread evidence for storms or other turbulence events (e.g. tsunamis), winnowing alone could not generate shell beds where none had previously existed. Instead, variations in sediment supply are construed as the principal cause of shelly-mudstone cycles. Shell-rich deposits accrue during periods of siliciclastic sediment starvation and relatively shell-free mud accumulates during periods of sediment influx. Tempestite proximality and episodic starvation models lead to contrasting predictions about proximal-to-distal facies patterns. These are: (i) large versus small volumes of distally-deposited, bypassed mud; (ii) proximal grainstones and distal packstones versus distal grainstones and proximal packstones; and (iii) proximal versus distal amalgamation and condensation of shell beds. In this paper, these predictions are tested by (i) comparing meter-scale cycles from different horizons and depositional environments through the lower Cincinnatian succession (Kope through McMillan Formations representing deep subtidal through intertidal environments), and (ii) correlating intervals and individual meter-scale cycles from the Fairview Formation of the Cincinnati Arch (shallow subtidal) north and west into the Maquoketa Shale (deep subtidal) in subsurface of Ohio and Indiana. Both approaches show patterns consistent with episodic starvation, not winnowing, including: (i) small differences in stratigraphic thickness indicate small volumes of bypassed mud; (ii) discrete distal deep-water grainstones that splay proximally into bundles of thinner shallow-water packstones alternating with shelly muds show that grainstones formed from a lack of, rather than removal of mud; and (iii) distal shell bed amalgamation and condensation (and corresponding proximal splaying) of shell beds shows a proximal source of mud. Thus, winnowing by storms or other turbulence events did not generate shell beds or cycles from undifferentiated sediments despite abundant evidence for storm deposition. High-resolution correlations imply that the shell-bed and mud-bed hemicycles reflect simultaneous basin-wide changes in sedimentary style rather than contemporaneous facies belts that track sea-level. In this sense, shell-rich and mud-rich hemicycles are “non-Waltherian” facies

    Status and Relative Abundance of Alabama Shad, \u3ci\u3eAlosa alabamae\u3c/i\u3e, in Alabama

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    Alabama Shad, Alosa alabamae, an anadromous fish found historically from the Mississippi River basin eastward to the Suwanee River, has experienced population declines and even extirpation in some States. In Alabama, A. alabamae have been found in rivers of the Mobile River basin and Conecuh, Yellow, and Choctawhatchee rivers in the coastal Gulf Plain. We report on our directed and targeted efforts to assess the current status and relative abundance of A. alabamae in Alabama and compare our results to past A. alabamae surveys in Alabama. We completed 52 sampling trips and expended 129.5 hours of boat-electrofishing effort targeting A. alabamae. Sampling was conducted during the spring to coincide with the spring-spawning migration at historical sites and sites conducive for the collection of A. alabamae. No A. alabamae was collected from the Mobile River basin (i.e., Alabama and Tombigbee rivers) and only one A. alabamae was collected from the Conecuh River. We collected seven A. alabamae in 2011 and three in 2018 from the Choctawhatchee River. For the Choctawhatchee River population, our results indicated a precipitous decline in abundance by 71% and 98% from 1999/2000 to 2011 and 2018, respectively. In addition, our results support the extirpation of A. alabamae from the Mobile River basin and a severely depressed population in the Conecuh River. Although A. alabamae was recently denied listing under the Endangered Species Act by the National Marine Fisheries Service due to lack of apparent range-wide extinction, our results indicate what was once considered the second largest population of A. alabamae from the Choctawhatchee River is on the verge of extirpation. Alosa alabamae could become extirpated from Alabama in the near future, which is a significant portion of its range

    Electrochemical Monitoring Of Electrogalvanizing Solutions

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    The corrosion resistance of steel is vastly improved when a zinc cathodic protective layer is applied. In recent years there has been renewed interest in producing this galvanized coating electrolytically. As with many deposition processes, the control of the operating parameters is very important in order to produce good quality zinc coatings. The homogeneity, ductility and smoothness of the zinc layer are critical. These factors are usually influenced by the electrochemical nature of the solution and organic additives are often used to assist in control. Studies on the polarization behavior of solutions for electro galvanizing electrolytes were made. Cyclic voltammetry techniques were used to develop methods which might be applicable in monitoring the active organic content of liquor ice in solution. The morphologies and orientations of the zinc were studied using SEM and X-ray diffraction techniques. © 1986 Chapman and Hall Ltd

    Upper Ordovician Strata of Southern Ohio-Indiana: Shales, Shell Beds, Storms, Sediment Starvation, and Cycles

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    The Cincinnatian Series (ca. 450 to 442 Ma) of the Cincinnati Arch features some of the most spectacular Ordovician fossils in the world. The rich faunas of bryozoans, brachiopods, molluscs, echinoderms, and trilobites are preserved as discrete shell-rich limestones, cyclically interbedded with sparsely fossiliferous shales and mudstones that may yield exceptionally preserved trilobites and crinoids. Similar successions of shell beds interbedded with mudstones are common components of Paleozoic successions. In such successions, the genesis of the highly concentrated shell beds is often attributed to storm-winnowing, but is this the whole story? This trip will offer an overview of the classic Cincinnatian Series, with ample opportunity for examining and collecting the rich fossil assemblages throughout much of the succession. Discussions will focus on the origin of interbedded mudstone-limestone cycles. We will emphasize depositional processes, particularly the role of intermittent siliciclastic sediment supply, carbonate (shell) production, and winnowing by storms and other high-energy events in a critical discussion of the storm-winnowing model

    Calibrating Water Depths of Ordovician Communities: Lithological and Ecological Controls on Depositional Gradients in Upper Ordovician Strata of Southern Ohio and North-Central Kentucky, USA

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    Limestone and shale facies of the Upper Ordovician Grant Lake Formation (Katian: Cincinnatian, Maysvillian) are well exposed in the Cincinnati Arch region of southern Ohio and north-central Kentucky, USA. These rocks record a gradual change in lithofacies and biofacies along a gently northward-sloping ramp. This gradient spans very shallow, olive-gray, platy, laminated dolostones with sparse ostracodes in the south to offshore, nodular, phosphatic, brachiopod-rich limestones and marls in the north. This study uses facies analysis in outcrop to determine paleoenvironmental parameters, particularly those related to water depth (e.g., position of the photic zone and shoreline, relative degree of environmental energy). Within a tightly correlated stratigraphic interval (the Mount Auburn and Straight Creek members of the Grant Lake Formation and the Terrill Member of the Ashlock Formation), we document the occurrence of paleoenvironmental indicators, including desiccation cracks and light-depth indicators, such as red and green algal fossils and oncolites. This permitted recognition of a ramp with an average gradient of 10.20 cm water depth per horizontal kilometer. Thus, shallow subtidal (.lagoonal.) deposits in the upramp portion fall within the 1.5.6 m depth range, cross-bedded grainstones representing shoal-type environments fall within the 6.18 m depth range and subtidal, shell-rich deposits in the downramp portion fall within the 20.30 m depth range. These estimates match interpretations of depth independently derived from faunal and sedimentologic evidence that previously suggested a gentle ramp gradient and contribute to ongoing and future high-resolution paleontologic and stratigraphic studies of the Cincinnati Arch region

    DINOSAUR FOOTPRINTS FROM THE GLEN ROSE FORMATION (PALUXY RIVER, DINOSAUR VALLEY STATE PARK, SOMERVELL COUNTY, TEXAS)

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    Dinosaur footprints are found in the Glen Rose Formation and other Lower Cretaceous stratigraphic units over much of central Texas (Pittman, 1989; Rogers, 2002; Farlow et al., 2006). Dinosaur tracks were discovered in the rocky bed of the Paluxy River, near the town of Glen Rose, Texas, early in the 20th Century (Jasinski, 2008; Farlow et al., 2012b). Ellis W. Shuler of Southern Methodist University did pioneering studies on the dinosaur tracks (Shuler 1917, 1935, 1937), and Langston (1974) summarized much of the early literature. What really put the dinosaur footprints of the Paluxy River on the map, though, were the herculean efforts that Roland T. Bird of the American Museum of Natural History made to secure trackway slabs for display at that institution and at the Texas Memorial Museum in Austin (Bird, 1985; Jasinski, 2008). In 1970 Dinosaur Valley State Park was created to protect the dinosaur footprints. This guidebook briefly summarizes earlier work, and also serves as an interim report of research of our group still in progress, concerned with identifying the makers of the Paluxy River footprints, and determining what those animals were up to as they made their tracks. We will offer some comparisons of the dinosaur tracks of the Glen Rose Formation with those from other ichnofaunas around the world. The last quarter-century has seen an explosive increase in the technical literature dealing with dinosaur footprints, and we cannot possibly cite all of the relevant studies. For the sake of brevity we will emphasize publications from the present century, and summary papers and books, as much as possible. Even with this restriction, however, the literature is so vast that the literature-cited “tail” of this report starts to wag the “dog” of the text

    Safety and efficacy of the hybrid approach in coronary chronic total occlusion percutaneous coronary intervention: The Hybrid Video Registry

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    Objectives The aim of the Hybrid Video Registry (HVR) is to assess the acute safety and efficacy of the Hybrid Approach in comparison to other contemporary methods of CTO‐PCI. Background: Recently, multiple techniques in Percutaneous Coronary Intervention (PCI) for coronary Chronic Total Occlusions (CTO) have been synthesized into a method referred to as the “Hybrid Approach”. Methods About 194 video‐taped timed live cases from CTO‐PCI training workshops were analyzed by independent data abstractors and compared to three contemporary CTO‐PCI registries stratified by case complexity based on the J‐CTO score. Results Overall procedural success was 95% of all cases attempted with an excellent safety profile. In the most complex lesion subset, which made up 45% of all HVR cases, success was 92.8%, which was significantly higher than either the Royal Bromptom (78.9%), or Japanese‐CTO (73.3%) registries, P = 0.04 Hybrid vs. Royal Brompton, P = 0.006 Hybrid vs. Japanese‐CTO). The Hybrid Approach was also associated with shorter procedure times and lower contrast utilization. Conclusions In a real world angiographic registry of complex CTOs, the Hybrid Approach to CTO‐PCI is safe, and may be superior to other contemporary approaches to CTO intervention with respect to procedural success and efficiency among a diverse group of operators and lesion complexity

    Clinical failures of endovascular abdominal aortic aneurysm repair: Incidence, causes, and management

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    AbstractObjective: Despite well-documented good early results and benefits of endoluminal stent graft repair of abdominal aortic aneurysm (J Vasc Surg 2002;35:1137-44.)(AAA), the long-term outcome of this method of treatment remains uncertain. In particular, concern exists that late effectiveness and durability are inferior to that of open repair. To determine the incidence and causes of clinical failures of endovascular AAA repair, a 7-year experience with 362 primary AAA endografts was reviewed. Methods: Clinical failures were defined as deaths within 30 days of the procedure, conversions (early and late) to open AAA repair, AAA rupture after endoluminal treatment, or AAA sac growth of more than 5 mm in maximal diameter despite endograft repair. Endoleak status per se was not considered unless it resulted in an adverse event. If clinical problems arose but could be corrected with catheter-based therapies or limited surgical procedures, thereby maintaining the integrity of successful stent graft treatment of the AAA, such cases were considered as primary assisted success and not classified as clinical failures. Results: The average follow-up period was 1.5 years. Six deaths (1.6%) occurred after the procedure, all in elderly patients or patients at high risk. Five patients (1.4%) needed early conversion (immediate, 2 days) to open repair for access problems or technical difficulties with deployment, resulting in an implantation success rate of 98.6%. Eight patients (2.2%) underwent late conversion for a variety of problems, including AAA expansion (n = 4), endograft thrombosis (n = 1), secondary graft infection (n = 2), and rupture at 3 years (n = 1). Rupture occurred in an additional two patients for a total incidence rate of 0.8%. AAA sac growth of greater than 5 mm was observed in 20 patients (5.6%), four of whom have undergone successful catheter-based treatments to date. Overall, 39 patients (10.7%) needed catheter-based (n = 45) or limited surgical (n = 4) reinterventions for a variety of late problems that were successful in 92%. Conclusion: In our 7-year experience, one or more clinical failures of endovascular AAA repair were observed in 31 patients (8.3%). Reinterventions were necessitated in a total of 10.7% of patients but were usually successful in maintaining AAA exclusion and limiting AAA growth. These results emphasize that endovascular repair provides good results and many benefits for most properly selected patients but is not as durable as standard open repair. (J Vasc Surg 2002;35:1137-44.

    A systematic review of community participation measures for people with intellectual disabilities

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    Background: Community participation is considered a fundamental aspect of quality of life and one of the essential goals of services for people with intellectual disabilities (ID), yet there is no agreed way of measuring community participation. Method: Two systematic searches were performed across eight electronic databases to identify measures of community participation and identify validation studies for each measure. Measures were included if they were developed for adults with ID, measured extent of participation and had published information regarding content and psychometric properties. Each measure was evaluated on the basis of psychometric properties and in relation to coverage of nine domains of community participation from the International Classification of Functioning, Disability and Health (ICF). Results: Eleven measures were selected with the quality rating scores varying substantially ranging from 2-11 of a possible 16. Conclusions: The majority of measures were not sufficiently psychometrically tested. Findings suggest a need for the development of a psychometrically robust instrument
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