ISO observations of molecular hydrogen in the DR 21 bipolar outflow

We demonstrate that a wide range of molecular hydrogen excitation can be observed in protostellar outflows at wavelengths in excess of 5 μm. Cold H₂ in DR 21 is detected through the pure rotational transitions in the ground vibrational level (0–0). Hot H₂ is detected in pure rotational transitions within higher vibrational levels (1–1, 1–2, etc.). Although this emission is relatively weak, we have detected two 1–1 lines in the DR 21 outflow with the ISO SWS instrument. We thus investigate molecular excitation over energy levels corresponding to the temperature range 1015–15 722 K, without the uncertainty introduced by differential extinction when employing near-infrared data.
This gas is thermally excited. We uncover a rather low H₂ excitation in the DR 21 West Peak. The line emission cannot be produced from single C-shocks or J-shocks; a range of shock strengths is required. This suggests that bow shocks and/or bow-generated supersonic turbulence is responsible. We are able to distinguish this shock-excited gas from the fluoresced gas detected in the K band, providing support for the dual-excitation model of Fernandes, Brand & Burton.     

RXTE spectroscopy of GRS 1915+105

The galactic superluminal motion source GRS 1915+105 has been extensively observed with the RXTE satellite over the last two years. More than 250 RXTE pointings have been performed until mid-May 1998 with more than 1.5 Msec exposure time on roughly a weekly basis. Here we report on first results of our spectral analysis of a major part of these pointed RXTE observations. We establish the existence of at least 5 spectral components and present the changes of these components over the last two years.     

Stable isotope (O,H, S) relationships in Tertiary basalts and their mantle xenoliths from the Northern Hessian Depression,W.-Germany

¹⁸O/¹⁶O, ³⁴S/³²S, and D/H ratios as well as vacuum-fusion H₂O⁺ contents were measured for late Tertiary volcanic basaltic rocks ranging in composition from quartz tholeiites and alkali olivine basalts to melilite-bearing olivine nephelinites and for peridotite xenoliths from the Northern Hessian Depression of W.-Germany. Measured Oisotope ratios in both basalts and peridotites were corrected for variable degree of post-eruption, secondary alteration. The ranges and means of corrected ¹⁸O values ( SMOW) for the North Hessian lavas and peridotites are: (i) 8 tholeiites: ca. +6.1 to +7.3 (¯x=+6.6), (ii) 21 alkali olivine basalts: ca. +5.4 to +7.6 (¯x=+6.5), (iii) 19 nepheline basanites, limburgites, and olivine nephelinites: ca. +5.3 to +8.0 (¯x=+6.6), and (iv) 23 peridotites: +5.1 to 7.0 (¯x+6.0). The ³⁴S values ( CDT) for the tholeiites range from –0.6 to +1.4 (¯x=–0.03) and for the alkali basalts range from +0.9 to +8.6 (¯x=+2.5). The approximate D value ( SMOW) of the pristine basalts and peridotites is estimated to have been ca. –90The quartz tholeiites appear to have had a different genetic history than the alkali basalts. Supported by chemical evidence, the ¹⁸O and ⁸⁷Sr enrichment observed in the tholeiites suggests low crustal contamination of parental olivine tholeiite melts, derived from a depleted mantle source. The contamination by crustal partial melts may have occurred in granulitic lower crust during differentiation. By contrast the high ¹⁸O and ³⁴S values observed for the alkali basalts and peridotites are best explained in terms of metasomatic alteration of the mantle source region by fluids enriched in ¹⁸O, K, and incompatible trace elements prior to partial melting. The ¹⁸O-K relationships for the peridotites indicate that the mantle beneath the Northern Hessian Depression has had a complex stable isotope history involving at least two distinct metasomatic events. The earlier event involved a CO₂-rich fluid which modified ¹⁸O/¹⁶O ratios without altering the mineralogical character of the mantle peridotite. The second event involved an aqueous fluid, which mainly altered the clinopyroxene and introduced phlogopite (plus possibly apatite, carbonate, and amphibole). It superimposed an ¹⁸O and K enrichment upon a previously altered mantle.     

Facies and paleogeographic importance of the pre-rift limestones from NE-Egypt/Sinai

The depositional environments of the Phanerozoic limestones of northeastern Egypt were reconstructed, based on microfacies and fossil content of the following limestonedominated sequences: Late Carboniferous, Late Anisian/ Ladinian (Carnian?), Bajocian/Kimmeridgian, Aptian/ Albian, Late Cenomaman/Early Turonian, Late Coniacian, Maastrichtian, Late Paleocene/Early Eocene. The African Craton in the south and the Tethyan sea in the north mainly controlled the sedimentation of most Phanerozoic strata; they increase in thickness towards the north, due to the gentle north/northwest dip of the Precambrian cratonal basement. Different subsiding areas enabled the filling of different depocenters since Jurassic times (with a maximum during the Cretaceous).The Early/Middle Cretaceous sediments were deposited along the broad North-African shelf system, with nearshore depositional environments, characterized by the interfingering of siliciclastics with marls and limestones; maximum thicknesses were encountered in several shallow depocenters. The Mid-Cretaceous platform was destroyed during Late Cretaceous times: Synsedimentary folding in the northern areas and vertical block fault movements further south (along rejuvenated pre-existing fault systems) are due to a N/NW-ward drift of the African Plate. Broad areas of North Africa were covered by chalks and marls in Senonian times, while phosphates and platform carbonates were locally deposited, due to synsedimentary structural unrest. The synsedimentary tectonic movements came to an end in Late Cretaceous times and were rejuvenated in Early Tertiary. The beginning Red Sea/Gulf of Suez rift influenced the sedimentation processes of the neighbouring Early Tertiary strata. Carbonates were mainly formed close to the uplifted areas, while the sedimentation of marls, clays and chalks prevailed in most other areas.

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Zusammenfassung Im Oberkarbon, Oberanis/Ladin (Carn?), Bajoc/Kimmeridge, Apt/Alb, Obercenoman/Unterturon, Oberconiac, Maastricht und Oberpaleozän/Untereozän treten kalkbetonte Abfolgen in Nordostägypten auf, deren Charakteristika mit Hilfe der Mikrofazies und des Fossilinhaltes beschrieben werden. Die Sedimentationsmuster der meisten phanerozoischen Ablagerungen können in einer stark vereinfachten Annäherung auf das Zusammenwirken festländischer Ablagerungsprozesse (Afrikanischer Kraton) im Süden und mariner Sedimentation (Tethys) weiter im Norden zurückgeführt werden. Die Sedimentmächtigkeiten nehmen generell nach Norden zu, was auf ein sanftes Einfallen des präkambrischen kristallinen Grundgebirges nach N/NW zurückzuführen ist. Daneben ist eine unterschiedlich starke Absenkung und Sedimentauffüllung verschiedener Depocenter seit dem Jura festzustellen.Die unter-/mittelkretazischen Sedimente wurden im Bereich des breiten, nordafrikanischen Schelfsystems abgelagert, das in verschiedene, überwiegend küstennahe Ablagerungsbereiche untergliedert werden kann; diese sind durch die Verzahnung von Siliziklastika mit Mergeln und Kalken gekennzeichnet und erreichen maximale Mächtigkeiten innerhalb der flachen Depocenter. Die mittelkretazische Plattform zerbrach in der Oberkreide: Synsedimentäre Faltung im Norden und Blockverwerfung weiter südlich (entlang reaktivierter alter Störungssysteme) werden auf die N/ NW Drift der Afrikanischen Platte zurückgeführt. Weite Gebiete Nordostafrikas wurden im Senon von ausgedehnten Kreide- und Mergelablagerungen bedeckt; die lokalen Vorkommen von Phosphaten und Plattformkarbonaten sind an synsedimentäre Strukturen gebunden. Im Alttertiär sind erneut synsedimentäre tektonische Bewegungen festzustellen (die auch im Zusammenhang mit dem beginnenden Rifting von Rotem Meer und Golf von Suez stehen). In der Umrandung herausgehobener Horstblöcke fand Karbonatsedimentation statt, während in den übrigen Gebieten Mergel, Tonsteine und Kreide (Chalks) abgelagert wurden.

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Résumé Les conditions de dépôt des calcaires phanérozoïques du nord-est de l'Egypte ont été reconstituées à partir des microfaciès et du contenu en fossiles des séries suivantes à dominante calcaire: Carbonifère supérieur, Amsien supérieur/Ladinien /(Carnien), Bajocien/Kimmeridgien, Aptien/Albien, Cénomanien supérieur/Turonien inférieur, Coniacien supérieur, Maestrichtien, Paléocène supérieur/ Eocène inférieur. La sédimentation de la plupart des couches phanérozoïques s'est organisée en fonction de la présence du craton africain au sud et de la Téthvs au nord; leur épaisseur augmente vers le nord, en relation avec la descente progressive vers le nord-nord-ouest de la surface du craton pré-cambrien. Des phénomènes de subsidence différentielle sont à l'origine de diverses aires d'accumulation importante à partir du Jurassique (avec un maximum au cours du Crétacé).Les sédiments d'âge crétacé inférieur et moyen se sont déposés le long du shelf nord-africain dans divers milieux littoraux, caractérisés par l'interdigitation de siliciclastites, de marnes et de calcaires, avec une puissance maximale dans les aires d'accumulation subsidentes. La plate-forme du Crétacé moyen a été détruite au cours du Crétacé supérieur: des plis syn-sédimentaires dans les parties septentrionales et des mouvements verticaux de »block faulting« plus au sud (le long du système de failles anciennes réactivées) traduisent la dérive vers le nord/nord ouest de la plaque africaine. Au Sénonien, de larges surfaces de l'Afrique du Nord ont été recouvertes de craies et de marnes, simultanément à des déôts locaux de phosphates et de carbonates de plate-forme, cette diversité traduisant l'instabilité structurale syn-sédimentaire. Les mouvements syn-sédimentaires ont pris fin au Crétacé supérieur puis ont été réactivés au début du Tertiaire. Le commencement de l'ouverture de la Mer Rouge et du Golfe de Suez a influencé la sédimentation du Tertiaire inférieur dans les régions voisines. Les carbonates se sont formés essentiellement dans les régions soulevées, tandis que le dépôt de marnes, argile et craies prévalait dans la plupart des autres endroits.

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Maturation of organic matter in neogene sediments from the Aderklaa oilfield,Vienna Basin,Austria

Summary Poil- and gas-producing horizons in the Tertiary section of the Vienna Basin are intercalated with calcareous shales. In this study, the shales are examined in view of their source rock potential.36 shales from 780 to 2812 m of six inch well cores from Aderklaa 78 hole were analysed for organic carbon by coulometric titration method. Organic C values vary from 0.22 to 2.04% with a mean value of 0.81%. A slight increase in the lower parts of the hole reflects initial differences in organic carbon content. Total bitumen extracts vary between 1.2 and 70.2 mg/100 g shale with a mean value of 270 ppm bitumen compared to a mean of 2480 ppm for average calcareous shale source rock.Aderklaa bitumen largely consists of unaltered material, perhaps being derived early from lipids. Only the deepest bitumen (2812 m) has higher saturated hydrocarbon content which is regarded as contamination from the underlying reservoir. Investigation of the Aderklaa kerogens from 9 shale samples suggests that they are type III kerogens, consisting almost entirely of vitrinite in the deepest sample examined. From vitrinite reflectance (R ₀=0.36 to 0.53, increasing downhole from 820 to 2703 m) it is obvious that kerogens are insufficiently mature to have produced major amounts of hydrocarbons. Plots of the atomic H/C versus O/C ratios corroborate the type III, terrigenous, plant-derived characteristic of Aderklaa kerogens.These investigations of the nature and state of preservation of the Neogene organic matter indicates that the petroleum window lies within pre-Tertiary basement, and that the temperatures were not sufficient for significant degradation of the Neogene Type III kerogen. However, the high hetero-compound content of numerous Vienna crudes suggests contamination with bitumens from this Tertiary organic matter.

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Der Reifegrad organischer Substanz in neogenen Sedimenten des Ölfeldes Akerklaa im Wiener Becken

Zusammenfassung Seit 1930 wird aus tertiären Abfolgen des Wiener Beckens Öl und Gas gefördert. Zwischen tertiäre Speichergesteine sind kalkige Schiefer eingeschaltet, die von früheren Autoren als mögliche Muttergesteine angesehen werden. In dieser Arbeit wird der Reifegrad des organischen Materials in den Schiefern untersucht.Organischer Kohlenstoff wurde in 36 Schieferproben (780 bis 2812 m) aus der Aderklaa 78 Bohrung durch coulometrische Titration bestimmt. Die Werte schwanken zwischen 0,22 und 2,04% C_org und weisen einen Mittelwert von 0,81% auf. Leichte Variation der Werte im unteren Teil der Bohrung sind auf unterschiedliche Anteile des ursprünglichen organischen Materials zurückzuführen.Bitumen-Extrakte ergaben zwischen 1,2 und 70,2 mg/100 g Schiefer mit einem Mittelwert von 270 ppm, im Vergleich zu 2480 ppm Mittelwert für kalkige Schiefer als Muttergestein. Die Bitumen bestehen aus wenig degradiertem, möglicherweise aus Lipiden stammenden organischen Material. Der relativ große Gehalt an gesättigten Kohlenwasserstoffen in Bitumen aus der tiefsten Probe (2812 m) ist wahrscheinlich auf Kontamination durch ein unterliegendes Reservoir zurückzuführen.Untersuchungen des Kerogens an 9 Proben ergab Typ III Kerogen, welches in der tiefsten Probe fast ausschließlich aus Vitrinit besteht. Vitrinit-Reflexionsmessungen (R ₀=0,36 bis 0,53, zunehmende Werte von 820 bis 2703 m) deuten einen geringen Reifegrad an der ausschließt, daß dedeutende Mengen Kohlenwasserstoffe abgespaltet worden sind. Eine Betrachtung der HC- und O/C-Elementverhältnisse gibt weitere Hinweise auf terrigenes, pflanzliches, Typ III Kerogen in den Aderklaa-Proben.Aus der Gesamtheit der Daten über die Zusammensetzung und den Reifegrad des neogenen organischen Materials wird geschlossen, daß keine bedeutende Degradation stattgefunden hat, und daß das petroleum window in prä-tertiären Schichten liegen muß. Der Gehalt an Hetero-Verbindungen in den geförderten Ölen deutet jedoch an, daß es zu Kontaminationen durch das neogene organische Material gekommen ist.

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With 8 Figures     

Model considerations for the evolution of carbonate groundwaters in the Schwäbische Alb (Federal Republic of Germany)

The evolution of carbonate groundwaters may occur in a so-called open or closed system or under conditions between the extremes. In order to distinguish between the cases the chemistry of the water and the carbon isotope composition of the dissolved carbonate, the carbonate rock and the soil CO₂ of the recharge area must be known. Model calculations based on measurements of the above parameters show that ground-waters in the “Schwäbische Alb”, Federal Republic of Germany, are evolved essentially under closed-system conditions. The average measured carbon isotope composition of the water is δ ¹³C = ?13.7%₀ vs. calculated values of δ ¹³C = ?13.5%₀ and δ ¹³C = ?18.5%₀ assuming a closed and an open system, respectively. In model calculations for closed-system conditions the origin of sulfate ions has to be considered.     

Ecological classification of macrophytes and phytobenthos for rivers in Germany according to the water framework directive

A new assessment system for macrophytes and phytobenthos in German rivers meeting the requirements of the Water Framework Directive (WFD) of the European Community is described. Biocoenotic types based on biological, chemical and hydromorphological data from over 200 river sites covering the main ecoregions, hydromorphological stream types and degradation forms have been defined. For developing a classification system the quality element macrophytes and phytobenthos was divided into three components: macrophytes, benthic diatoms and remaining phytobenthos. For macrophytes seven types including one subtype, for benthic diatoms 14 types including three subtypes and for the remaining phytobenthos five river types were identified. The benthic vegetation at reference condition was described for most of the river types. Degradation is characterised as deviation in benthic vegetation species composition and abundance from the reference biocoenosis. For classification in five ecological status classes, several metrics were developed and used in combination with existing indices. For some of the described river types additional investigations are necessary before a classification system can be developed.     

Metastable staurolite–cordierite assemblage of the Bossòst dome: Late Variscan decompression and polyphase metamorphism in the Axial Zone of the central Pyrenees

A kilometre-scale shear zone is recognized in the Cambro–Ordovician schist of the Bossòst dome, a Variscan metamorphic and structural dome in the Axial Zone of the central Pyrenees. Non-coaxial deformation is recorded by rotated garnet and staurolite porphyroblasts following regional metamorphism M₁, while coaxial conditions prevailed during later contact metamorphic M₂ growth of andalusite and cordierite. Mineral compositions and bulk rock analyses show that garnet–staurolite–andalusite–cordierite assemblages are significantly enriched in Mg and Mn over the garnet–staurolite assemblage, which lacks sufficient Mg for cordierite to form. The garnet–staurolite assemblage preserves conditions during M₁, estimated by AFM diagrams and P–T pseudosections to be 5.5 kbar and 580 °C, respectively. Pseudosections also indicate that staurolite is not a stable phase in cordierite–andalusite assemblages of M₂, suggesting polyphase metamorphism and decompression along a clockwise P–T path for the staurolite–cordierite–andalusite assemblages. This concurs with proposed extensional tectonics along the regional shear zone. To cite this article: J.E. Mezger et al., C. R. Geoscience 336 (2004).