SCOPIX – digital processing of X-ray images for the enhancement of sedimentary structures in undisturbed core slabs

X-ray images of sediment core allow recognition of fine-scaled sedimentary structures which traditional epoxy casts or lacquer peels are unable to resolve. The X-ray imaging system SCOPIX has the additional advantage of acquiring high-resolution digital pictures suitable for further analysis by advanced image processing techniques. Because of the frequent presence of both physical and biogenic sedimentary structures in undisturbed sediment cores, two image analysis procedures have been established which simplify the information contained in the images (in term of structures and facies), and allow a quantitative characterization of the observed structures. This form of parametrization of the image structure constitutes an additional source of information for a better interpretation of the physical processes responsible for the generation of the sedimentary structures.     

Nutrient budgets and trophic state in a hypersaline coastal lagoon: Lagoa de Araruama, Brazil

Lagoa de Araruama in the state of Rio de Janeiro, Brazil, is a hypersaline lagoon with salinity varying spatially from 45 to 56. We collected water samples during monthly cruises throughout the lagoon, and along the streams feeding the system, from April 1991 to March 1992. Nutrients and other water quality parameters exhibited great spatial and temporal variations. Mass balance calculations indicate large amounts of anthropogenic nutrient inputs. The data indicate that the lagoon currently is oligotrophic but is in a state of transition to become a mesotrophic system. Molar dissolved inorganic nitrogen:dissolved inorganic phosphorus (DIN/DIP) varied between 2.2:1 and 659:1 with a volume-weighted average of 22:1. The high DIN/DIP ratio contrasts with that found in nearby lagoons, suggesting that phytoplankton primary production is limited by phosphorus in Lagoa de Araruama. The major loss of DIP is apparently driven by biological assimilation and diagenic reactions in the sediments. Calculations indicate that the lagoon is slightly net autotrophic at +0.9 mol C m⁻² yr⁻¹. This suggests that the biomass of the primary producers is restricted by phosphorus availability. Phosphorus retention in the sediment and the hypersaline state of the lagoon prevent changes in autotrophic communities and the formation of eutrophic conditions.     

An upper limit on the aperture separation of ion drift meters

An upper limit has been calculated on the effective aperture separation or detector thickness of ion drift meters of two fundamental types. The limit applies to meters which compare currents collected by detectors with different view directions at the same retarding potential and to meters which measure the entire thermal ion distribution function. For both types, a single scanned detector may be employed instead of multiple detectors, in which case the limit applies to twice the radius of curvature of the path followed by the detector aperture during a scan, (i.e. the diameter of a spinning payload). The limit was found to be important in two cases. First, in the F region on spacecraft with stringent electrostatic cleanliness requirements, the 10% error limit was found to be 40 cm. Second, in the E region, the limit was found to be 1 cm.Originally submitted to the journalSpace Science Instrumentation.Deceased.     

Crustal structure of the Rhenish Massif: results of deep seismic reflection lines Dekorp 2-North and 2-North-Q

The reflection seismic line DEKORP 2-N reveals an almost complete cross section through the Rhenohercynian Zone, the most external part of the Variscan orogen in Europe.The northern part of DEKORP 2-N and a NE-directed branch (2-N-Q) reveal the Cretaceous of the Münsterland basin and the underlying folded Palaeozoic rocks. The northward decreasing intensity of folding is depicted in great detail by the highly reflective Late Carboniferous coal-measures and deeper reflections down to the level of the Givetian/Frasnian shallow-water carbonates.In the Devonian and older rocks of the Rhenish Massif, bedding is only represented by relatively weak, short and irregular reflections. These are truncated by stronger, southward dipping reflections, which exhibit the listric curvature and flat/ramp geometry characteristic of faults. In the northern part of the section, the thrusts appear to be blind. From the Ebbe Anticline southwards, prominent reflections can be correlated with important thrust faults known from the surface, such as the Ebbe-, Siegen-, Müsen- and Sackpfeife- Thrusts, as well as further important thrust faults in the Lahn- and Dill Synclines. The basal thrust of the extremely thin-skinned Giessen Nappe is only recognizable for a very short distance.At depth, the thrusts flatten out in a relatively transparent zone between 3–5 s TWT, with strongly reflective bands at its bottom and top. The transparent zone might correlate with a high-conductivity layer detected in a magnetotelluric survey; it represents either graphitic metapelites or a zone with an interconnected, brine-filled pore space. The seismic record relates either to lithological differences, or to rheological boundaries.The lower crust in the north is characterized by a relatively transparent zone, which wedges out towards south under the northern margin of the Siegen Anticline. Comparisons with a similar feature in the ECORS profile »Nord de la France« suggest that the transparent zones in both sections correspond to a pre-Palaeozoic basement, such as it underlies the Brabant Massif. Further south, the lower crust is increasingly reflective.The curvilinear, thrust-related reflections are cut by a conjugate set of much weaker, N- and S-dipping reflectors indicating a later deformation with pure shear. Displacement of some marker reflections suggests late- or post-Variscan compression.In an alternative interpretation, these straight and weak reflections represent the only thrust faults, while the curvilinear elements might relate to bedding.A southward rise of the Moho from approx. 11 to 8.5 s TWT is probably due to Tertiary rifting.

---

Zusammenfassung Das reflexionsseismische Profil DEKORP 2-N stellt einen fast vollständigen Querschnitt durch das Rhenohercynikum dar.Der nördliche Teil des Profiles 2-N sowie ein SW/NE-verlaufender Abzweig (2-N-Q) zeigen die Transgression der Münsterländer Kreide und das unterlagernde gefaltete Paläozoikum. Schichtgebundene Reflektoren (flözführendes Karbon, devonischer Massenkalk) bilden das Ausklingen der variscischen Faltung nach NW detailliert ab.In den devonischen und vordevonischen Sedimenten des rechtsrheinischen Schiefergebirges erzeugt die Schichtung nur relativ schwache, kurze und unregelmäßige Reflexionen. Diese werden von stärkeren, südfallenden Reflektoren abgeschnitten, die aufgrund ihrer listrischen Krümmung und flat/ramp-Geometrie wahrscheinlich als Überschiebungen zu interpretieren sind. Im Nordteil des Schiefergebirges sind diese Überschiebungen offenbar blind, werden also nahe der Oberfläche durch Faltung kompensiert. Im Ebbe-Sattel und weiter südlich lassen sich die meisten der starken, südfallenden Reflektoren zweifelsfrei mit bekannten Großüberschiebungen korrelieren (Ebbe-, Siegen-, Müsen-, Sackpfeife-Ü, sowie weitere Überschiebungen in der Lahn- u. Dill-Mulde). Die Basisüberschiebung der Giessen-Decke wird nur teilweise abgebildet.Zur Tiefe hin zeigen die Überschiebungen ein zunehmend flacheres Einfallen, und verschwinden in einer relativ transparenten Zone zwischen 3 und 5 s TWT, die im Hangenden und Liegenden durch dünne, stark reflektive Zonen begrenzt ist. Diese transparente Zone entspricht möglicherweise einer Zone hoher integrierter Leitfähigkeit, die in einem begleitenden magnetotellurischen Experiment nachgewiesen worden ist; es handelt sich entweder um einen Graphit-führenden Phyllit-Horizont oder eine mächtigere permeable Zone mit Elektrolyt-gefülltem Porenraum. Die hochreflektiven Bänder über und unter der transparenten Zone entsprechen entweder lithologischen Kontrasten oder rheologischen Grenzen, die vermutlich von einer scherenden Verformung überprägt worden sind.Die Unterkruste im N-Teil des Profiles enthält einen relativ transparenten Bereich, der nach Süden hin unter dem Nordteil des Siegener Sattels keilförmig ausläuft. Ein ähnliches Bild zeigt der Nordteil des ECORS-Profiles »Nord de la France«. Die transparenten Bereiche beider Profile entsprechen wahrscheinlich einem prä-paläozoischen kristallinen Basement, das das Brabanter Massif unterlagert und sich rechtsrheinisch fortsetzt. Südlich des transparenten Keiles wird die Unterkruste zunehmend reflexionsreicher. Die listrisch gekrümmten, an Überschiebungen gebundenen Reflektoren werden von einem konjugierten System schwächerer, N- u. S-fallender Reflektoren abgeschnitten, die auf eine jüngere, bruchhafte Verformung durch reine Scherung hindeuten. Der Versatz einiger älterer Reflektoren deutet auf spät- oder postvariscische Kompression hin.In einer alternativen Interpretation werden nur diese jüngeren Reflektoren als Überschiebungen gedeutet; die älteren, gekrümmten Elemente müßten dann primären lithologischen Grenzen entsprechen.Die Moho steigt von ca. 11 s TWT im N auf 8.5 s TWT unter dem Taunus an. Die Krustenverdünnung im Süden geht wahrscheinlich auf Dehnung im Tertiär zurück.

---

Résumé Le profil sismique par réflexion DEKORP-2-N représente une transversale quasiment complète à travers la zone rhénohercynienne. La partie septentrionale du DEKORP-2-N ainsi qu'une branche de direction SW-NE (2-N-Q) mettent en évidence la transgression du Crétacé du Münsterland sur le Paléozoïque sous-jacent plissé. Des réflecteurs liés à la stratification (à savoir: le Houiller et les calcaires de plate-forme dévoniens) illustrent de façon détaillée la diminution vers le nord de l'intensité du plissement varisque.Dans les sédiments dévoniens et pré-dévoniens du Massif Rhénan à l'est du Rhin, la stratification ne fournit que que des réflexions relativement faibles, courtes et irrégulières. Elles sont tronquées par des réflecteurs plus intenses, à pendage sud qui, en raison de leur courbure listrique et de leur géométrie en «flat/ramp», doivent être interprétés comme des chevauchements. Dans la partie septentrionale du Massif, ces chevauchements sont apparemment aveugles, c'est-à-dire qu'ils sont compensés, près de la surface, par le plissement. Dans l'anticlinal d'Ebbe, ainsi que plus au sud, la plupart des réflecteurs intenses à plongement sud peuvent être corrélés avec des chevauchements majeurs connus, tels ceux de Ebbe, Siegen, Müsen, Sackpfeife et d'autres encore dans les synclinaux de la Lahn et de la Dill. Le chevauchement basai de la nappe de Giessen n'est que partiellement représenté.Les chevauchements deviennent de plus en plus plats en profondeur pour disparaître dans une zone relativement transparente qui se situe entre 3–5 sec TWT. Celle-ci est prise en sandwich par des zones minces à forte réflectivité. La zone transparente correspond probablement à une zone de conductivité intégrée élevée dont l'existence a par ailleurs été démontrée dans un essai magnétotellurique mené parallèlement. Il s'agit soit d'un horizon phyllitique graphiteux, soit d'une zone perméable plus épaisse dont les pores sont remplis d'électrolyte. Les bandes à haute réflectivité au-dessus et en-dessous de la zone transparente correspondent soit à des contrastes lithologiques, soit à des limites rhéologiques probablement accentuées par la déformation cisaillante.La croûte inférieure dans la partie septentrionale du profil comporte un domaine relativement transparent qui s'amincit vers le S et se termine, en dessous de la partie nord de l'anticlinal de Siegen, en forme de coin. La partie nord du profil ECORS «Nord de la France» montre une image semblable.Les domaines transparents des deux profils correspondent vraisemblablement à un soubassement cristallin pré-paléozoïque qui est sousjacent au Paléozoïque du Massif du Brabant et se prolonge vers l'est au-delà du Rhin. Au sud du coin transparent, la réflectivité de la croûte inférieure va en augmentant. Les réflecteurs listriques liés à des chevauchements sont recoupés par un système conjugué de réflecteurs plus faibles à plongement nord et sud qui indiquent des failles plus récentes. Le déplacement de quelques réflecteurs plus anciens suggère l'effet d'une compression tardiou post-varisque.Dans une interprétation alternative, seuls ces réflecteurs plus récents sont considérés comme correspondant à des chevauchements. Dans ce cas, les éléments courbes plus anciens devraient représenter des limites lithologiques primaires.Le Moho s'élève à partir de 11 sec TWT environ au nord jusqu'à 8.5 sec TWT en-dessous du Taunus. L'amincissement crustal au sud résulterait du régime de distension survenu au Tertiaire.

---

DEKORP 2 Nord. x-t- ray-tracing'a. 6,0 6,6 /, — 7,0 8,2 /. 6,25 /. 28 30 . , .

---

Abbreviations MORB Mid-Ocean Ridge Basalt - TWT two-way travel time, seconds (s) - CMP common mid-point - VP vibration point - SNR signal to noise ratio     

Holocene record of productivity in the NW Iberian continental shelf

A multiproxy approach (textural characteristics, heavy metal concentrations and benthic foraminifera data) was adopted to study the OMEX core KSGX 40, collected at the Galicia Mud Deposit (NW Iberian outer continental shelf) and recording the last ca. 4.8 ka cal BP. Geochemical profiles of Fe, Mn, Zn, Co, Cr, Cu, Ni, Pb, Al and Ca show significant temporal variations. Benthic foraminifera productivity proxy suggests that the recorded muddy events were contemporaneous of a higher C_org flux to the marine benthic environment. The higher flux of organic matter, following a long-term intensification of the upwelling and coinciding with a finer sedimentation, led to depressed levels of oxygen beneath the water-sediments interface and to early diagenetic processes of several redox-sensitive elements.     

Land-surface scheme validation using the Oklahoma Atmospheric Surface-layer Instrumentation System (OASIS) and Oklahoma Mesonet data: Preliminary results

Summary The Oklahoma Atmospheric Surface-layer Instrumentation System (OASIS) is a recently-developed observational system that collects, archives, and quality controls atmospheric, surface, and soil data in real-time from 90 stations across Oklahoma. Ten of the 90 sites, termed “super sites”, are equipped with additional sonic anemometry and four-component net radiometers to provide complete observations of the surface energy balance. Oklahoma Mesonet and OASIS data are used in this study to validate the sensitivity and accuracy of a land-surface scheme within a numerical prediction model. The Advanced Regional Prediction System (ARPS) is a three-dimensional, nonhydrostatic mesoscale model developed by the Center for Analysis and Prediction of Storms (CAPS) at the University of Oklahoma. The land-surface model (LSM) used within ARPS is the Interactions Soil Biosphere Atmosphere (ISBA) scheme. Mesonet and OASIS data collected from the super site located in Norman, Oklahoma, are used as verification for the ISBA. Research presented in this study outlines the challenges in developing, maintaining, and using in-situ data for model validation. Such problems as instrument error, surface heterogeneity, and non-closure of the surface energy budget limit data accuracy. Preliminary results of model validation focus on the sensitivity of the soil physics within the ISBA scheme. Model sensitivity to vegetation cover, surface roughness, and soil type are investigated. Furthermore, several recent improvements to ISBA are evaluated and compared to observations. This study concludes that the sensitivity of the ISBA to a priori soil and vegetation type is detrimental for this scheme to be used in a mesoscale model without improved treatment of surface heterogeneity. Received November 18, 2001 Revised December 28, 2001     

Evaluating Tidal Wetland Restoration Performance Using National Estuarine Research Reserve System Reference Sites and the Restoration Performance Index (RPI)

Evaluations of tidal wetland restoration efforts suffer from a lack of appropriate reference sites and standardized methods among projects. To help address these issues, the National Estuarine Research Reserve System (NERRS) and the NOAA Restoration Center engaged in a partnership to monitor ecological responses and evaluate 17 tidal wetland restoration projects associated with five reserves. The goals of this study were to (1) determine the level of restoration achieved at each project using the restoration performance index (RPI), which compares change in parameters over time between reference and restoration sites, (2) compare hydrologic and excavation restoration projects using the RPI, (3) identify key indicator parameters for assessing restoration effectiveness, and (4) evaluate the value of the NERRS as reference sites for local restoration projects. We found that the RPI, modified for this study, was an effective tool for evaluating relative differences in restoration performance; most projects achieved an intermediate level of restoration from 2008 to 2010, and two sites became very similar to their paired reference sites, indicating that the restoration efforts were highly effective. There were no differences in RPI scores between hydrologic and excavation restoration project types. Two abiotic parameters (marsh platform elevation and groundwater level) were significantly correlated with vegetation community structure and thus can potentially influence restoration performance. Our results highlight the value of the NERRS as reference sites for assessing tidal wetland restoration projects and provide improved guidance for scientists and restoration practitioners by highlighting the RPI as a trajectory analysis tool and identifying key monitoring parameters.     

The Three American Wests

In the twenty-first century, there are three American Wests, which cut across cultural, political, physical, and economic boundaries. Parts of the West are booming, building homes, and adding population; others are legally off limits to such development; and much of the West has been bypassed by such development and growth. These are called here the Booming West, Protected West, and Bypassed West. Maps of climate, political boundaries, ethnic and racial identities, or presidential voting patterns do not match these three Wests. Each West has a different relationship to the others and might see them as threats or opportunities, and each West can be expected to grow in different areas at the expense of other Wests. The boundaries between the three Wests could be important locations; sharp transitions can exist between Wests, perhaps nowhere more so than where a fast growing metro area abuts a national park or forest boundary. Finally, the effects of climate change cut across the three Wests and have different implications for their future. Continued population growth will further emphasize the boundaries between each of the three Wests and raise the stakes for their control.     

上部地壳的流体作用与大理岩的低温塑性

本文应用光学显微镜、透射电子显微镜和阴极发光显微镜系统研究了Ｗａｔｅｒｂｅｒｇ断层带（纳米比亚）内粗晶大理岩中发育的构造岩,宏观碎裂结构与微观糜棱装结构是断层构造岩的主要特点。巨大的孪形碎屑与弥漫的细小粒质形成了鲜明的反差,广泛发育的压溶颖合线与多阶段方解石细脉遍布构造带不同部位,ＴＥＭ亚微粒粒度具有简单的峰值分布（～０．３～０．４μｍ）,但动态重结晶颗粒的粒度却具有较大的变化范围（０．１～３．０