Lower Mississippian Lithostratigraphy, Northern Arkansas

Lower Mississippian lithostratigraphic units in northern Arkansas are (ascending order) the Bachelor, St. Joe, and Boone Formations. These formations disconformably overlie Middle Ordovician to Upper Devonian strata and are overlain disconformably by Meramecan or Chesterian strata. The Bachelor Formation is generally a thin (less than 0.3 m), persistent, orthoquartzitic sandstone with common to abundant phosphatic pebbles overlain by a green silty shale. In northwestern Arkansas, the Bachelor Formation commonly lacks sandstone. The Bachelor Formation has been confused previously with the Sylamore (Upper Devonian) and older sandstone units. Although commonly regarded as a member of the Boone Formation, the St. Joe Limestone should be raised to formation rank in accordance with the earlier proposal of Cline (1934). The St. Joe Limestone in northwestern Arkansas can be subdivided into (ascending order) the Compton, Northview, and Pierson Members which are recognized as formations in Missouri. In the type region, northcentral Arkansas, subdivision of the St. Joe is precluded by lack of the shaly Northview Member. A marked color change from gray to red from northwestern to northcentral Arkansas is accompanied by a general increase in the allochemical constituents. The St. Joe Boone boundary is taken to be at the first persistent chert. This contact generally coincides with a thin calcareous shale unit and a marked decrease in carbonate grain size

Devonian Sandstone Lithostratigraphy, Northern Arkansas

Two areas of Devonian sandstone development may be recognized in northern Arkansas. In northwestern Arkansas, the Clifty Formation comprises a massively bedded, super mature quartz arenite of Middle Devonian age overlain by thinner bedded, phosphatic quartz arenite and chert breccia of the Sylamore Sandstone Member, Chattanooga Shale (Upper Devonian). This sequence overlies Ordovician strata (Powell or Everton) and is succeeded by the Chattanooga Shale and strata of Lower Mississippian age. In north-central Arkansas, the Clifty Formation is absent and the Chattanooga Shale may develop sandstone at its base and top. Occasionally the Chattanooga Shale is absent and the entire interval may be Upper Devonian sandstone. These Upper Devonian sandstones are phosphatic, mature quartz arenites referred to the Sylamore Member except where they overlie the Chattanooga Shale. In these cases, the sandstone is recognized as an informal upper member of the Chattanooga. Reports of Lower Mississippian Sylamore Sandstone in north-central Arkansas are regarded as misidentification of the Bachelor Formation (Middle Kinderhookian

A Computer Program for Population Analysis

A computer program for population analysis has been developed that is simply written, but relatively sophisticated. It consists of three parts: computation and tabulation of data, statistical analysis and plotting. The program can be understood readily by computation center personnel and requires a minimum of modification for use in most facilities. Once the program is instituted, an instructor need only have knowledge of the format requirements to use it. Lack of a programming background need not prevent an instructor from using the computer for population analysis

Type Kinderhook Ammonoids

Lower Mississippian rocks in the type area of North America have produced only a few scattered ammonoid cephalopods. Those specimens from southeastern Iowa and northwestern Missouri lie within the general vicinity of the designated type locality, near Kinderhook, Illinois. In this area, age relationships for strata near the Devonian-Mississippian boundary have been established largely through studies of their conodont faunas. However, some of the ammonoids from within the Kinderhook and adjacent beds are critical for long-range correlation. Although most of these ammonoid occurrences have been recorded, minor changes in correlation can be suggested by reexamination of the specimens, together with a review of the physical stratigraphy and the associated conodont faunal data. The Kinderhookian Wassonville Member of the Hampton Formation in southeastern Iowa and the Chouteau Limestone of Missouri fall within the lower Pericyclus-Stufe of the upper Tournaisian Stage as these units are designated for the early Lower Carboniferous of Western Europe. The index genus is present, but relatively rare in North America; associated ammonoids include Gattendorfia, Prodromites and Imitoceras. All of these genera are known from the type Kinderhook area. The same genera, plus Muensteroceras and Beyrichoceras appear to characterize the overlying Osagean beds. The directly underlying Upper Devonian also contains Imitoceras, but Cymaclymenia and Cyrtoclymenia in addition

Discussions and Reviews : Problems of inter-American neighborliness: a review Bryce Wood, The Making of the Good Neighbor Policy William Manger, Pan America in Crisis: The Future of the OAS

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67865/2/10.1177_002200276200600406.pd

Age and Correlation of the Moorefield Shale (Upper Mississippian) in its Type Area, Northeastern Arkansas

The name Moorefield was proposed by Adams and Ulrich (1904) for exposures of gray to brown, phosphatic shale with a basal limestone, overlying the Lower Mississippian Boone Formation, and underlying the Upper Mississippian Batesville Sandstone, in the vicinity of Moorefield, Independence County, northeastern Arkansas. Gordon (1944) 1) restricted the name Moorefield to the lower limestone-bearing interval, 2) applied a new name, Ruddell, to the succeeding shale section that comprises the bulk of the interval, with a type area near Moorefield, and 3) interpreted the interval contacts as unconformities. The name Ruddell was used for the revised Geological Map of Arkansas (1993), but later publications by the Arkansas Geological Survey and other sources refer the entire interval to the Moorefield Shale, and report a maximum thickness of 91.44 m. (300 feet). Age assignments for the Moorefield Shale are based almost entirely on ammonoid cephalopods (e.g. Gordon 1965, Saunders et al. 1977, Korn and Titus 2011). Brachiopods (e.g. Girty 1911) have provided a supporting role, but never to the precision of the ammonoids. Initially, Gordon (1965) recognized two ammonoid zones and four subzones through all the Moorefield, except the base. Korn and Titus (2011) reexamined Gordon’s published ammonoid assemblages, and made additional collections from the type Moorefield. They recognized only two Moorefield ammonoid zones: the lower Goniatites eganensis - Girtyoceras welleri zone, succeeded by the upper Goniatites multiliratus zone concentrated near the middle of the interval. The best age assignment for these abundant, middle Moorefield ammonoid assemblages is to the lower Chesterian Series (Korn and Titus 2011). The unfossiliferous lower Moorefield Shale spans the Meramecian-Chesterian boundary. The upper section, above the ammonoid occurrences, but also barren of ammonoids, and other biostratigraphically useful fossils, likely extends to at least the middle Chesterian. Thus, the bulk of the Moorefield formation represents the Chesterian, not the Meramecian Series. This age assignment is complicated further by the reduction of the lithostratigraphic units comprising the type Meramecian Series (Lane and Brenckle 2005), and a lack of ammonoid assemblages in its type area, St. Louis County, Missouri

Early Cementation of the Short Creek Oolite Member, Boone Formation (Osagean, Lower Mississippian), Northern Arkansas

The Short Creek Oolite is the only formally named member of the Boone Formation in northern Arkansas. It lacks bedding features, and oolith concentrations that would suggest a shoal environment, and it occurs at variable stratigraphic horizons within the upper Boone Formation consistent with episodic deposition as grainflow slurries. As with modern oolite examples, such as Joulters Cays, Bahamas, the Short Creek preserves numerous intraclasts, and at least one large olistolith indicating an early cementation history

Partial Nephrectomy in a Patient with a Left Ventricular Assist Device

Left ventricular assist device (LVAD) use has increased as a bridge to heart transplant as well as destination therapy in patients with severe heart failure. Presence of LVAD is not a contraindication to noncardiac surgery but does present special challenges to the surgical, anesthesia, and cardiac teams. We present the case of a 40-year-old woman with idiopathic cardiomyopathy necessitating LVAD who underwent left partial nephrectomy for a renal mass. She had undergone three nondiagnostic percutaneous image-guided biopsies. Left partial nephrectomy was performed. Perioperative care was without incident due to careful oversight by a multidisciplinary team. Pathology revealed high-grade clear cell renal cell carcinoma (RCC) with negative margins. Polytetrafluoroethylene (PTFE) bolsters were misidentified six months postoperatively on computed tomography (CT) at an outside institution as a retained laparotomy sponge. This is, to our knowledge, the first report of a partial nephrectomy performed in a patient with LVAD