Morphological variations in the ammonite Scaphites of the Blue Hill Member, Carlile Shale, Upper Cretaceous, Kansas

30 p., 2 pl., 7 fig.http://paleo.ku.edu/contributions.htm

Endosiphuncular structures in Ordovician and Silurian cephalopods

14 p., 3 pl., 4 fig.http://paleo.ku.edu/contributions.htm

Proposed magnetostratigraphy susceptibility magnetostratotype for the Eifelian-Givetian GSSP (Anti-Atlas, Morocco)

The magnetosusceptibility event and cyclostratigraphy (MSEC) record for the Eifelian-Givetian Global Boundary Stratotype Section and Point (GSSP) located in the western Sahara of southeastern Morocco is used to establish a sequence of magnetostratigraphic susceptibility units organized into magnetostratigraphic susceptibility zones (MSZ) and magnetostratigraphic susceptibility subzones (MSSZ). Magnetic susceptibility data are summarized into two complete MSZs (Atrous and Mech Irdane) and two partial MSZs (Gheris and Rissani). The Atrous (Upper Eifelian) is comprised of 3 MSSZs and the Mech Irdane (uppermost Eifelian and lowermost Givetian) of 11 MSSZs. The Eifelian-Givetian boundary falls within Mech Irdane MSSZ 2 making the magnetosubzone an important boundary marker unit. Large-scale transgressive and regressive patterns in the MSEC data establish that the Eifelian-Givetian boundary in the GSSP sequence occurs immediately after the first regressive pulse following the transgressive conditions established during the Atrous MSZ. The Lower Kačák/otomari Event occurs in Atrous MSSZ 3 and Kačák/otomari Event occurs in Mech Irdane MSSZ 1. The magnetic properties of the MSZs and MSSZs are tested by comparison with a coeval magnetostratigraphic susceptibility sequence in the Montagne Noire region of southern France

Paleomagnetism of paleozoic asphaltic deposits in southern Oklahoma, USA

Paleomagnetic measurements on asphaltic samples from two formations in southern Oklahoma have been performed. A bioclastic unit from the Boggy Formation, known as the Buckhorn asphalt, exhibited a stable, characteristic remanent moment (RM) after A.F. demagnetization between 5–20 mT. We infer from our data that very fine, possibly authigenic magnetite, like that shown to have a genetic relationship with the migration through rocks of hydrocarbons [Elmore et al., 1987], is the primary RM carrier in these samples. The tilt corrected paleopole for the Buckhorn asphalt (121.9 E; 43.5N; δp=1.3; δm=2.3) falls on the Early Permian Apparent Polar Wander Path for North America of Irving and Irving [1982], using a 30 Ma window (270–280 Ma). Because the Boggy Form‐ation, containing the Buckhorn asphalt, was depos‐ited during the Late Pennsylvanian (Desmoinesian), we interpret the data to indicate magnetization during minor uplift in the Early Permian of the Arbuckle Mountain region. The RM appears to have been acquired at this time, probably as the result of magnetite production facilitated by the introduction time of sulfate reducing bacteria. Copyright 1988 by the American Geophysical Union

The Magneto-Susceptibility Event and Cyclostratigraphy (MSEC) Method Used in Geological Correlation of Devonian Rocks from Anti-Atlas Morocco

Magneto-Susceptibility Event and Cyclostratigraphy (MSEC) is used here as a means of establishing sensitive chronostratigraphic markers and chronohorizons useful for high-resolution correlation. MSEC is a composite of the magnetic susceptibility (MS) record of marine strata and the coeval biostratigraphic record and, similar to chronozones, zones based on MSEC data have boundaries that are isochronous. MS, a measure of the concentration of magnetic grains in sediments, proxies for the ratio of lithogenic to biogenic components. Controls on the detrital input of lithogenic material include eustasy and climate, however induced, and sea floor/basin subsidence. The development of an initial MSEC composite reference curve for the Middle-Upper Devonian of the Anti-Atlas region of southern Morocco is presented and discussed in the context of global sea level transgressive and regressive cycles. MSEC trends, composed of increasing MS magnitudes, correlate well with episodes of regression, whereas trends of decreasing MS magnitudes correlate with episodes of transgression. © Copyright 1999. The American Association of Petroleum Geologists. All rights reserved

Magnetosusceptibility event and cyclostratigraphy (MSEC) of the Eifelian-Givetian GSSP and associated boundary sequences in north Africa and Europe

MagnetosusceptibiUty event and cyclostratigraphy (MSEC) is used to define magnetic susceptibility (MS) signatures for the Eifelian-Givetian GSSP in southern Morocco and four other Eifelian-Givetian boundary sequences in Morocco, southern France, and the Czech Republic. MSEC data from the GSSP are used to iden-tify nine first-order isochronous MSEC events for chronocorrelation. MSEC data clearly define a new abiotic Late Eife-lian MSEC Event that immediately precedes the Eife-lian-Givetian boundary and encompasses the biotic Kacak and otomari Events. The MSEC event begins in the upper Tortodus kockelianus kockelianus Zone and ends in the upper Polygnathus ensensis Zone. This Event occurs in the same stratigraphie position in the boundary sequences studied. The characteristics of the Late Eifelian MSEC Event are those of a prolonged high stand in global sea level

Impact ejecta layer from the mid-Devonian: Possible connection to global mass extinctions

We have found evidence for a bolide impacting Earth in the mid-Devonian (∼380 million years ago), including high concentrations of shocked quartz, Ni, Cr, As, V, and Co anomalies; a large negative carbon isotope shift (-9 per mil); and microspherules and microcrysts at Jebel Mech Irdane in the Anti Atlas desert near Rissani, Morocco. This impact is important because it is coincident with a major global extinction event (Kacák/otomari event), suggesting a possible cause-and-effect relation between the impact and the extinction. The result may represent the extinction of as many as 40% of all living marine animal genera

Magnetostratigraphy susceptibility of the Frasnian/Famennian boundary

Magnetosusceptibility event and cyclostratigraphy (MSEC) is used to establish a non-polarity-based magnetostratigraphy susceptibility (MSS) between the stratotype region for the Frasnian/Famennian (F/F) boundary sequence in the Montagne Noire of southern France, the eastern Rheinisches Schiefergebirge of Germany, Belgium, the eastern Anti-Atlas of Morocco, and the Arbuckle Mountains of southern Oklahoma (USA). Despite differences of depositional environment, the MSS is remarkably consistent and can be described in the context of a hierarchy of magnetozones that allow the extension of correlation away from the Montagne Noire reference section. The nature of the controls on the influx of iron into the marine system produces a natural hierarchy of at least seven orders or magnetozones designated MSZ1, MSZ2, MSZ3, MSZ4, MSZ5, MSZ6, and MSZ7. These are characterized in terms of the magnitude of their duration. The MSS reference section of choice for the F/F boundary is the well-known Trench C at La Serre (LSC) in the northeastern Montagne Noire of southern France. The F/F boundary is located at the lower boundary of magnetozone La Serre Iα3b at La Serre as well as in all other sections studied. MSZ4 and MSZ5 magnetozones are used to establish intra- and inter-regional correlation between the reference sequence and the other regions. The base of the Upper Kellwasser event is as variable within the MSS zonation as it is within the biostratigraphic zonation, as is the position of the Lower Kellwasser event. © 2002 Elsevier Science B.V. All rights reserved

Global correlation using magnetic susceptibility data from Lower Devonian rocks

Magnetic susceptibility data from marine rocks can be used for global correlation because of synchronous variations in global erosion. We show here correlations between magnetic susceptibility data from two Lower Devonian; biostratigraphically well defined sections, one in northwestern Spain, and one from the Anti-Atlas region of Morocco. Using the Moroccan outcrop section, we correlate to cuttings from a Bolivian well with minimal biostratigraphic control. Using the magnetic susceptibility data, we identify the Lower Devonian, Pragian-Emsian, and lower-upper Emsian stage boundaries in the Bolivian well samples