Regional geologic environs and natural resources of Badia Sector, Jordan

 This paper summarizes the information on the geology and natural resources of the Jordan Badia Research and Development Programme. The research focused on the issue of the environment in arid lands as an aid to provide practical options for sustainable development. This paper presents results of field studies in the following areas related to the sustainable development of the Safawi area in the northern Jordan Badia; geomorphology, including landform, soil, lands, processes and hazards, geology and physical resources and surface water hydrology. Tertiary-Quaternary continental basalt flows and tuffs cover approximately 11 000 km², the majority of the Safawi area. In addition to extensive basalt lava flows, the programme area includes a variety of geological outcrops and potential sources of economic products that include the following: Tuff/Scoria, Zeolite/Olivine, Porcellanite, potential sources of aggregate/construction materials, ornamental stone, building stone, basalt for manufacturing of rock wool, and materials suitable for producing lightweight aggregate. The whole of the eastern Badia exhibits major fault systems, many of which were identified from Landsat TM images. The system of wadis which drains the Badia is extensive, with the general flow from the north to the south and south-west. A noticeable geomorphic surficial deposit occuring throughout much of the Badia is fine-grained, water-lain sediments that vary in size and character. The local designation for the fine sediment deposits is Qaa. An MSS scene for the area under consideration has been studied. Twelve major geomorphic subdivisions or zones can be identified. Individual land system units have been identified by traversing the programme area. Key sites have been visited based on Landsat TM image interpretation. To a large extent, key areas were subdivided after their initial identification on the Landsat scene and corroboration in the field. The surface drainage of the Badia region can be broadly divided into wadi systems, areas of distinct channelized flow, and Qaa, predominantly fine-grained sedimentary basins of low relief. Spatial variability in infiltration rates across the wadi-Qaa system were determined from field experiments. Infiltration rates were found to be medium-high in the wadi channels but decrease rapidly for the Qaa materials. Apparently runoff from wadi side slopes will be high, and water storage occurs along the wadi channels while ponding occurs in the Qaa areas. Received: 13 March 1997 · Accepted: 13 January 1998     

The Arctic Coastal Dynamics Database: A New Classification Scheme and Statistics on Arctic Permafrost Coastlines

Arctic permafrost coasts are sensitive to changing climate. The lengthening open water season and the increasing open water area are likely to induce greater erosion and threaten community and industry infrastructure as well as dramatically change nutrient pathways in the near-shore zone. The shallow, mediterranean Arctic Ocean is likely to be strongly affected by changes in currently poorly observed arctic coastal dynamics. We present a geomorphological classification scheme for the arctic coast, with 101,447?km of coastline in 1,315 segments. The average rate of erosion for the arctic coast is 0.5?m? year^?1 with high local and regional variability. Highest rates are observed in the Laptev, East Siberian, and Beaufort Seas. Strong spatial variability in associated database bluff height, ground carbon and ice content, and coastline movement highlights the need to estimate the relative importance of shifting coastal fluxes to the Arctic Ocean at multiple spatial scales.     

Isotopic datings of reddish granitoids in southern Värmland,southwestern Sweden

Three reddish granites from the Gneiss Complex of south-western Sweden have been dated with the U-Pb and one of them also with the Rb-Sr method. The Gneiss Complex consists of two mega-units separated by a tectonic discontinuity. The two granites from the western mega-unit (»the Western Gneiss Segment«) yield zircon upper-intercept ages of 1552 _–36 ⁺³⁸ and 1499 _–36 ⁺³⁶ Ma (2). These ages are minimum estimates of the intrusion ages, but the difference between the obtained and the true age is probably small. This assumption is based on studies of the morphology and internal structures of the zircons and also on air abrasion experiments.The third granite is located in the eastern mega-unit (the »Eastern Gneiss Segment«) and forms a number of small massifs, 50 m in diameter. The U-Pb and Rb-Sr ages agree within the limits of the errors — 1140 _–52 ⁺⁵⁴ Ma (upper intercept) and 1104 ± 100 Ma, respectively — but the obtained age is nevertheless dubious. Thin-section studies reveal that the zircons are heterogeneous with different types of material making up the inner and outer parts. Electron-microscopic studies as well as air abrasion and leaching experiments were performed to establish possible differences in age and chemistry between the inner and outer parts. The central parts are made up of almost pure ZrSiO₄ whereas the outer parts are layered with alternating pure ZrSiO₄ layers and layers rich in trace elements. The leaching and air abrasion data do not indicate any age difference between the inner and outer parts. This supports the validity of the upper-intercept age as an intrusion age.The Rb-Sr age is questionable since the obtained initial⁸⁷Sr/⁸⁶Sr ratio is as low as 0.7027. This cannot possibly be true for a felsic, late Proterozoic granite. A plausible explanation could be a rotation of the isochron due to migration of Rb and Sr during a low-grade event. This event is also responsible for the alteration of the biotites and plagioclases.These data provide additional evidence for extensive ensialic magmatism in the period succeeding the lithosphere-forming event.

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Zusammenfassung Drei rötliche Granite aus dem Südwestschwedischen Gneiskomplex sind mit der U-Pb Methode und einer davon zusätzlich mit der Rb-Sr Methode datiert worden. Der Gneiskomplex besteht aus zwei Haupteinheiten, die tektonisch voneinander getrennt sind. Zwei Granite aus der westlichen Haupteinheit (dem sogenannten »Western Gneiss Segment«) ergeben obere Schnittpunktsalter der Zirkone von 1552 _–36 ⁺³⁸ bzw. 1499 _–36 ⁺³⁶ Ma (2). Diese Alter stellen Minimumalter für die Instrusionen dar, die nur geringfügig jünger sind als die wahren Instrusionsaltern. Diese Vermutung stützt sich auf Untersuchungen der Morphologie und der internen Struktur der Zirkone sowie auf Experimente mit Hilfe der Luftabriebstechnik (air abrasion technique).Der dritte Granit stammt aus der östlichen Haupteinheit (dem sogenannten »Eastern Gneiss Segment«), in der er kleine Körper von etwa 50 m Durchmesser bildet. Die U-Pb und Rb-Sr Alter von 1140 _–52 ⁺⁵⁴ Ma (oberer Schnittpunkt), bzw. 1104 ± 100 Ma stimmen innerhalb des Fehlers überein. Trotzdem ist dieses Alter fragwürdig. Dünnschliffuntersuchungen zeigen, da\ die Zirkone heterogen sind, und da\ Rand und Kern unterschiedlich zusammengesetzt sind. Um Unterschiede in Alter und Chemismus zwischen Rand und Kern festzustellen, wurden Untersuchungen mit dem Elektronenmikroskop, Luftabriebsexperimente und Anätzexperimente durchgeführt. Die Kerne bestehen fast aus reinem ZrSiO₄, wogegen die äu\eren Ränder aus Wechsellagerungen von reinem ZrSiO₄ und Lagen mit hohem Spurenelementgehalt bestehen.Die Anätzversuche und die Luftabriebsexperimente brachten keinen Altersunterschied zwischen Rand und Kern. Diese Tatsachen sprechen dafür, da\ das obere Schnittpunktsalter dem Instrusionsalter entspricht.Das Rb-Sr Alter ist fragwürdig, zumal das⁸⁷Sr/⁸⁶Sr-Initialverhältnis einen sehr niedrigen Wert von 0,7027 aufweist, der für einen spätproterozoischen Granit viel zu niedrig ist. Eine mögliche Erklärung ist die Rotation der Isochrone wegen einer Migration von Rb und Sr während eines Ereignisses bei niedriger Temperatur, ein Ereignis, das auch für die Umwandlung von Biotit und Plagioklas verantwortlich zu sein scheint. Die oben aufgeführten Daten geben zusätzliche Hinweise für einen sialischen Magmatismus im Zeitraum des fortschreitenden Ereignisses der Bildung der Lithosphäre.

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Résumé Trois granites rougeâtres provenant du complexe gneissique du sud-ouest de la Suède ont été datés par la méthode U-Pb et, pour l'un d'entre eux, également par la méthode Rb-Sr. Le complexe gneissique consiste en deux grandes unités séparées par une discontinuité tectonique. Les zircons de deux granites provenant de l'unité occidentale (»Western Gneiss Segment«) fournissent des âges (intersection supérieure) de 1552 _–36 ⁺³⁸ et 1499 _–36 ⁺³⁶ Ma (2). Ces âges constituent des estimations minimales des âges d'intrusion, la différence entre l'âge mesuré et l'âge véritable étant probablement minime. Cette supposition se base sur l'étude de la morphologie et des structures internes des zircons, ainsi que sur des expériences d'abrasion à l'air.Le troisième granite est situé dans l'unité orientale (»Eastern Gneiss Segment«) et se présente en plusieurs massifs d'une cinquantaine de mètres de diamètre. Les âges U-Pb et Rb-Sr coÏncident dans les limites des erreurs (1140 _–52 ⁺⁵⁴ (point d'intersection supérieur) et 1104±100 Ma) l'âge obtenu étant néanmoins incertain. L'étude en coupes minces montre que les zircons sont hétérogènes, leurs parties centrales et périphériques présentant des constitutions différentes. Des examens au microscope électronique, ainsi que des essais d'abrasion à l'air et de corrosion à l'acide ont eté effectués afin de mettre en évidence des différences éventuelles d'âge et de composition chimique entre les parties contrales et périphériques. Tandis que les parties centrales consistent en ZrSiO₄ pratiquement pur, les parties extérieures se composent de couches de ZrSiO₄ pur alternant avec des couches contenant de multiples éléments en traces. Les données obtenues sur les grains corrodés à l'acide ou soumis à une abrasion à l'air n'indiquent cependant pas de différence d'âge entre les parties centrales et périphériques. Ceci confirme la validité de l'âge obtenu (point d'intersection supérieur) comme âge d'intrusion.L'âge Rb-Sr est douteux, étant donné que le rapport initial⁸⁷Sr/⁸⁶Sr n'est que de 0,7027, valeur improbable pour un granite felsique du ProtérozoÏque supérieur. Il paraÎt raisonnable de supposer une rotation de l'isochrone, due à une migration de Rb et Sr durant un événement à basse température. Cet événement serait également responsable de l'altération des biotites et des plagioclases. Ces données fournissent un argument supplémentaire en faveur d'un magmatisme ensialique pendant la période qui suit la formation de la lithosphère.

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- U/Pb, Rb/Sr. , . — . . Western Gneiss Segments — 1552 _–36 ⁺³⁸ 1499 _–36 ⁺³⁶ (2). . , air abrasion technique. — Eastern Gneiss Segments —, 50 . U/Pb 1140 _–52 ⁺⁵⁴ Ma ( ), Rb/Sr - 1104 ± 100 ; , . . , . , : , air abrasion technique . ZrSiO₄, ZrSiO₄, . air abrasion technique . , ., Rb/Sr, , ⁸⁷Sr/⁸⁶Sr (0,7027), . . - . — , , , . , .

     

Seasonal variation of hepatic mixed function oxidases in winter flounder (Pseudopleuronectes americanus)

Indices of hepatic mixed function oxidase (MFO) activity in winter flounder (Pseudopleuronectes americanus) were measured at approximately monthly intervals from November 1983 to October 1985. Benzo[a]pyrene hydroxylase and ethoxyresorufin O-deethylase activities and cytochromes P450 and b₅ were generally, but not significantly, higher in males than in females. The MFO activity varied seasonally, reaching a maximum during or shortly after spawning. Variation in MFO enzyme activity between sexes was never greater than 2-fold at any time, and within sex, no greater than 6-fold during the seasonal cycle. This variability is less than that caused by exposure to environmentally realistic levels of some pollutants; measurements of MFO activity in this species might therefore be used to indicate environmental contamination.     

Becoming Reading Group: reflections on assembling a collegiate,caring collective

ABSTRACT

In neoliberalising universities, collegial and collective practices such as reading groups are often positioned by students, staff and managers as less important than meeting individual KPIs (such as producing research publications, seeking research grants, or meeting the increasing demands of producing quality teaching outcomes.) However, reading groups can be vital for cultivating caring collectives and spaces of collegiality. In this paper we use assemblage thinking to explore 25 years of a Geography reading group at the University of Newcastle. The paper addresses two questions: what does reading together do and make possible; and how might we think about the labours of reading together as a way of building caring collectives. The paper draws on reflections from 24 past and present members of reading group to explore how these kinds of academic practices nourish our working lives.     

Chemical treatments for mobilizing arsenic from contaminated aquifer solids to accelerate remediation

Arsenic is a prevalent contaminant at US Superfund sites where remediation by pump and treat systems is often complicated by slow desorption of As from Fe and Al (hydr)oxides in aquifer solids. Chemical amendments that either compete with As for sorption sites or dissolve Fe and Al (hydr)oxides can increase As mobility and improve pump and treat remediation efficiency. The goal of this work was to determine optimal amendments for improving pump and treat at As contaminated sites such as the Vineland Chemical Co. Superfund site in southern New Jersey. Extraction and column experiments were performed using As contaminated aquifer solids (81 ± 1 mg/kg), site groundwater, and either phosphate (NaH₂PO₄·H₂O) or oxalic acid (C₂H₂O₄·2H₂O). In extraction experiments, phosphate mobilized between 11% and 94% of As from the aquifer solids depending on phosphate concentration and extraction time (1 mM–1 M; 1–24 h) and oxalic acid mobilized between 38% and 102% depending on oxalic acid concentration and extraction time (1–400 mM; 1–24 h). In column experiments, phosphate additions induced more As mobilization in the first few pore volumes but oxalic acid was more effective at mobilizing As overall and at lower amendment concentrations. At the end of the laboratory column experiments, 48% of As had been mobilized from the aquifer sediments with 100 mM phosphate and 88% had been mobilized with 10 mM oxalic acid compared with 5% with ambient groundwater alone. Furthermore, simple extrapolations based on pore volumes suggest that chemical treatments could lower the time necessary for clean up at the Vineland site from 600 a with ambient groundwater alone to potentially as little as 4 a with 10 mM oxalic acid.     

Boreas Book Reviews

Book reviewed in this article:
Climate change in the Holocene BENT ODGAARD
Quaternary palynology in eastern Europe BJÖRN E. BERGLUND     

Cryovolcanic features on Titan's surface as revealed by the Cassini Titan Radar Mapper

The Cassini Titan Radar Mapper obtained Synthetic Aperture Radar images of Titan's surface during four fly-bys during the mission's first year. These images show that Titan's surface is very complex geologically, showing evidence of major planetary geologic processes, including cryovolcanism. This paper discusses the variety of cryovolcanic features identified from SAR images, their possible origin, and their geologic context. The features which we identify as cryovolcanic in origin include a large (180 km diameter) volcanic construct (dome or shield), several extensive flows, and three calderas which appear to be the source of flows. The composition of the cryomagma on Titan is still unknown, but constraints on rheological properties can be estimated using flow thickness. Rheological properties of one flow were estimated and appear inconsistent with ammonia-water slurries, and possibly more consistent with ammonia-water-methanol slurries. The extent of cryovolcanism on Titan is still not known, as only a small fraction of the surface has been imaged at sufficient resolution. Energetic considerations suggest that cryovolcanism may have been a dominant process in the resurfacing of Titan.     

Mapping of Titan: Results from the first Titan radar passes

The first two swaths collected by Cassini's Titan Radar Mapper were obtained in October of 2004 (Ta) and February of 2005 (T3). The Ta swath provides evidence for cryovolcanic processes, the possible occurrence of fluvial channels and lakes, and some tectonic activity. The T3 swath has extensive areas of dunes and two large impact craters. We interpret the brightness variations in much of the swaths to result from roughness variations caused by fracturing and erosion of Titan's icy surface, with additional contributions from a combination of volume scattering and compositional variations. Despite the small amount of Titan mapped to date, the significant differences between the terrains of the two swaths suggest that Titan is geologically complex. The overall scarcity of impact craters provides evidence that the surface imaged to date is relatively young, with resurfacing by cryovolcanism, fluvial erosion, aeolian erosion, and likely atmospheric deposition of materials. Future radar swaths will help to further define the nature of and extent to which internal and external processes have shaped Titan's surface.     

The effects of Hurricanes Katrina and Rita on seabed polycyclic aromatic hydrocarbon dynamics in the Gulf of Mexico

To assess the extent to which Hurricanes Katrina and Rita affected polycyclic aromatic hydrocarbons (PAH) in the Gulf of Mexico (GOM), sediment cores were analyzed in late 2005 from: a shallow shelf, a deeper shelf, and a marsh station. Sediment geochronology, fabric, and geochemistry show that the 2005 storms deposited ∼10 cm of sediment to the surface of a core at 5-12A. Bulk carbon geochemistry and PAH isomers in this top layer suggest that the source of sediment to the top portion of core 5-12A was from a relatively more marine area. Particulate PAHs in the marsh core (04 M) appeared unaffected by the storms while sediments in the core from Station 5-1B (deeper shelf) were affected minimally (some possible storm-derived deposition). Substantial amounts of PAH-laden particles may have been displaced from the seabed in shallow areas of the water column in the GOM by these 2005 storms.