Mahafir: A water harvesting system in the Eastern Jordan (Badia) Eesert

There are many different water harvesting systems in the Middle East and the operation of one type, the mahafir, was investigated in the Badia Region of Jordan. Mahafir are crescent and rectangular shaped excavations dug into the playa surface, now filled with sediment. Their previous volumes were estimated through topographical survey of the surrounding earth mounds. The average depth of the mahafir was found to be 3.2 m; storing a total water volume of 111,619 m³ at Maharouta and 55,005 m³ at Anka. The mahafir only occupy 4% of the playa surface and their source of water is primarily direct rainfall onto the playa surface augmented by runoff from adjacent slopes. Taking annual rainfalls as an input from 1963 to 1992 and even assuming rainfall harvesting is only 10% effective it appears that the full water storage potential of the mahafir could be met in most years.     

Phlogopite in calc-alkaline lamprophyres of Northern England

Summary Phlogopite mica is the major unaltered phase in minette and kersantite dikes in the Cross Fell and Taythes inliers in northwestern England. The compositional zonation trend in the micas from Mg-rich, Cr-bearing cores to Fe, Ti, Ba-rich, low Cr margins, or rims, is similar to that reported for micas from minettes and kersantites worldwide. Complex mantling and zoning trends suggest that the phenocrystal mica assemblage is a hybrid one formed by the mixing of magmas of broadly similar composition which have undergone different amounts of fractional crystallization. The magmas are considered to have beeen produced in a continuously replenished fractionating magma chamber. The lamprophyres have a common source and were probably derived by the extensive fractionation of a basic mantle-derived magma.

---

Phlogopit in kalk-alkalischen lamprophyren von Nord-England

Zusammenfassung Phlogopit ist die wichtigste, unveränderte Phase in Minetten und kersantitischen Gängen in den Cross Fell and Taythes Gebieten von Nordwest-England. Die Zonierung der Zusammensetzung in den Glimmern von Mg-reichen, Cr-führenden Kernen zu Fe, Ti, Ba-reichen Rändern mit niedrigen Cr-Gehalten ist ähnlich der, die von Glimmern in Minetten und Kersantiten weltweit ermittelt wurde. Komplexe Ummantelung und Zonierung weisen darauf hin, daß die Glimmer-Vergesellschaftung, die weithin idiomorph ist, durch die Mischung von Magmen weithin ähnlicher Zusammensetzung entstanden ist, welche in verschiedenem Ausmaß von Kristallisationsfraktionierung betroffen waren. Die Magmen dürften in einer kontinuierlich aufgefüllten, fraktionierten Magmenkammer entstanden sein. Die Lamprophyre haben einen gemeinsamen Ursprung und gehen wahrscheinlich auf die extensive Fraktionierung eines basischen Magmas von Mantel-Herkunft zurück.

---

---

With 5 Figures     

The lamprophyre facies

Summary Lamprophyres are a polygenetic group of rocks that have formed by the crystallization of common magma types, including lamproites and kimberlites, under volatile-rich conditions. The term lamprophyre is considered to have no genetic significance and the recognition of a lamprophyre facies is proposed as a means of conveying the concept that some members of a petrological clan crystallized under different conditions e.g. volatile-rich, to other members of that clan. A petrological clan is defined as suite of comagmatic rocks that have been derived from a particular parental magma which has been produced repeatedly in time and space. Lamprophyres are redefined as rocks which are characterized by the presence of euhedral-to-subhedral phenocrysts of mica and/or amphibole together with lesser clinopyroxene and/or melilite set in a groundmass which may consist (either singly or in various combinations) of plagioclase, alkali feldspar, feldspathoid, carbonate, monticellite, mica, amphibole, pyroxene, perovskite, Fe-Ti oxides and glass. The concept of a lamprophyre clan is considered to be unnecessary as it has no petrogenetic significance.

---

Die Lamprophyr-Fazies

Zusammenfassung Lamprophyre sind eine Gruppe polygenetischer Gesteine, die, einschließlich der Lamproite und Kimberlite, durch Kristallisation gewöhnlicher Magmentypen unter volatil-reichen Bedingungen entstehen. Der Begriff Lamprophyr wird in einem nicht genetischen Sinne verstanden. Das Erkennen einer Lamprophyr-Fazies wird als eine Möglichkeit betrachtet, dieses Konzept auf eine Kristallisation unter unterschiedlichen Bedingungen, z.B. volatil-reiche Kristallisationsbedingungen im Vergleich zu anderen Gesteinen desselben Clans, zu übertragen. Ein petrologischer Clan wird als eine komagmatische Suite, die aus einem bestimmten Ursprungsmagma, das zeitlich und räumlich wiederholt produziert wurde, definiert. Lamprophyre werden als Gesteine redefiniert, die durch eu- bis subhedrale Phänokristalle von Glimmern und/oder Amphibolen und untergeordnet Klinopyroxen und/oder Melilith in einer Grundmasse bestehend aus einem oder mehreren der Minerale Plagioklas, Alkalifeldspat, Foiden, Karbonat, Monticellit, Glimmer, Amphibol, Pyroxen, Perovskit, Fe-Ti-Oxiden und Glas charakterisiert sind. Das Konzept eines Lamprophyr-Clans wird für unnotwendig erachtet, da ihm keine petrogenetische Bedeutung zukommt.

     

The natural resources development debate in Canada

The current debate concerning natural resources developed in Canadais examined against the background of population distribution, electoral distribution, variations in regional economies, foreign investment, federal versus provincial jurisdiction over resources, and the demands for constitutional reform. These have resulted in an essential division between the resource producing regions of the west and, to a lesser extent the extreme east, and the resource consuming region in the centre. After establishing the context for resource development, the paper goes on to assess the debate as it has evolved with respect to offshore fishery resources on the Atlantic Coast, potash in Saskatchewan and petroleum and natural gas in the western provinces.     

Regional variation of Rayleigh wave attenuation coefficients in the Eastern Pacific

Seismograms recorded for five earthquakes on the east Pacific rise have been analyzed to obtain the attenuation coefficients of the fundamental Rayleigh mode for the eastern Pacific in the 15–110 second period range. The attenuation coefficients have been obtained using two new methods, a reference-station method, and an iterative method by which the seismic moment and regionalized attenuation coefficient values are obtained simultaneously after considering the effect of the source directivity and time-function. The reference-station method was applied to the entire eastern Pacific, excluding paths along the east Pacific rise. When using the iterative method we divided the eastern Pacific into three sub-regions, designated as the north-eastern Pacific, the Nazca plate and the east Pacific rise. Although much scatter is present, the data suggest that attenuation coefficients for the Nazca plate are higher than those for the northeastern Pacific, and both are substantially higher than average values obtained for the entire Pacific Ocean. Two paths that lie along or near the east Pacific rise are characterized by especially high attenuation coefficients. These values suggest that a low-Q zone exists beneath that narrow feature.     

Estimating growth rates of ferromanganese nodules from chemical compositions: implications for nodule formation processes

Using available information on the accretion rates and the bulk chemical compositions of oceanic ferromanganese nodules, it can be shown that the accumulation rate of manganese is proportional to the square of the accumulation rate of iron. This relationship has been used to derive an equation that predicts nodule growth rates from their chemical compositions. The equation accurately predicts growth rates up to about 50 mm/10⁶ yr, but yields incorrect rates for faster-growing concretions. From this relationship nodules underneath water of high primary productivity grow most rapidly and accumulate transition metals most rapidly; however, nodules from regions of highest primary productivity do not have the highest concentrations of nickel and copper. Reduction of manganese within the sediment column and remobilization of a fraction to the surface sediments adds manganese to nodules without substantially augmenting the supply of other transition elements. The addition of remobilized manganese to the nodule dilutes the concentrations of nickel, copper and iron, even though their rates of accumulation are also high.     

Scandium,cobalt and iron geochemistry of the Fen alkaline complex,southern Norway

Whole rock abundances of Sc, Co and total Fe are presented for the Fen carbonatite complex. Average Sc and Co abundances are as follows: urtites (Sc = 1.8 ppm; Co. 5.5 ppm), ijolites (6.6; 25), silicocarbonatites (3.2; 12.2), søvites (3.5, 8.6), damtjernites (24; 57), vipetoites (5.2, 36), rauhaugites (15, 26), rødberg (61, 28). With in the ijolite-søvite series Sc decreases with degree of differentiation due to removal of pyroxene and garnet. In the damtjernite-rødberg series Sc increases with differentiation due to concentration by volatiles involved in the metasomatic conversion of damtjernite to rødberg. Data for the ijolite-søvite series is opposite to trends for this series found in the Oka carbonatite complex.     

Résultats préliminaires sur la sédimentation pélagique de l'Atlantique tropical au Crétacé et au Tertiaire (plateau de Demerara,Leg ODP 207)

Five sites located on a bathymetric transect of the distal Demerara Rise were studied by ODP Leg 207. Albian sediments of essentially terrigenous nature (clay, siltstone, sandstone) are the oldest drilled stratigraphic levels and form apparently the top of the synrift sequence. They are overlain by Cenomanian to Santonian finely laminated black shales, rich in organic matter of marine origin, which accumulated on a thermally subsiding ramp. Early Campanian hiatuses are thought to be the result of final disjunction of Demerara Rise (South America) from Africa and the onset of deep water communication between the two Atlantic basins (south and central). The overlying Uppermost Cretaceous–Oligocene chalk includes rich and diversified calcareous plankton assemblages, as well as two radiolarian-rich intervals (Late Campanian and Middle Eocene). A complex erosional surface developed during the Late Oligocene–Early Miocene. Sedimentation was impeded since then on the intermediate and deep sites of Demerara Rise, possibly due to the action of deep submarine currents. To cite this article: T. Danelian et al., C. R. Geoscience 337 (2005).